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Publisher: Oxford University Press   (Total: 396 journals)

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Showing 1 - 200 of 396 Journals sorted alphabetically
ACS Symposium Series     Full-text available via subscription   (SJR: 0.189, CiteScore: 0)
Acta Biochimica et Biophysica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.79, CiteScore: 2)
Adaptation     Hybrid Journal   (Followers: 9, SJR: 0.143, CiteScore: 0)
Advances in Nutrition     Hybrid Journal   (Followers: 47, SJR: 2.196, CiteScore: 5)
Aesthetic Surgery J.     Hybrid Journal   (Followers: 6, SJR: 1.434, CiteScore: 1)
African Affairs     Hybrid Journal   (Followers: 64, SJR: 1.869, CiteScore: 2)
Age and Ageing     Hybrid Journal   (Followers: 91, SJR: 1.989, CiteScore: 4)
Alcohol and Alcoholism     Hybrid Journal   (Followers: 18, SJR: 1.376, CiteScore: 3)
American Entomologist     Full-text available via subscription   (Followers: 7)
American Historical Review     Hybrid Journal   (Followers: 152, SJR: 0.467, CiteScore: 1)
American J. of Agricultural Economics     Hybrid Journal   (Followers: 41, SJR: 2.113, CiteScore: 3)
American J. of Clinical Nutrition     Hybrid Journal   (Followers: 148, SJR: 3.438, CiteScore: 6)
American J. of Epidemiology     Hybrid Journal   (Followers: 176, SJR: 2.713, CiteScore: 3)
American J. of Hypertension     Hybrid Journal   (Followers: 25, SJR: 1.322, CiteScore: 3)
American J. of Jurisprudence     Hybrid Journal   (Followers: 18, SJR: 0.281, CiteScore: 1)
American J. of Legal History     Full-text available via subscription   (Followers: 8, SJR: 0.116, CiteScore: 0)
American Law and Economics Review     Hybrid Journal   (Followers: 27, SJR: 1.053, CiteScore: 1)
American Literary History     Hybrid Journal   (Followers: 15, SJR: 0.391, CiteScore: 0)
Analysis     Hybrid Journal   (Followers: 21, SJR: 1.038, CiteScore: 1)
Animal Frontiers     Hybrid Journal  
Annals of Behavioral Medicine     Hybrid Journal   (Followers: 15, SJR: 1.423, CiteScore: 3)
Annals of Botany     Hybrid Journal   (Followers: 36, SJR: 1.721, CiteScore: 4)
Annals of Oncology     Hybrid Journal   (Followers: 42, SJR: 5.599, CiteScore: 9)
Annals of the Entomological Society of America     Full-text available via subscription   (Followers: 10, SJR: 0.722, CiteScore: 1)
Annals of Work Exposures and Health     Hybrid Journal   (Followers: 32, SJR: 0.728, CiteScore: 2)
AoB Plants     Open Access   (Followers: 4, SJR: 1.28, CiteScore: 3)
Applied Economic Perspectives and Policy     Hybrid Journal   (Followers: 18, SJR: 0.858, CiteScore: 2)
Applied Linguistics     Hybrid Journal   (Followers: 56, SJR: 2.987, CiteScore: 3)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1, SJR: 1.241, CiteScore: 1)
Arbitration Intl.     Full-text available via subscription   (Followers: 20)
Arbitration Law Reports and Review     Hybrid Journal   (Followers: 14)
Archives of Clinical Neuropsychology     Hybrid Journal   (Followers: 30, SJR: 0.731, CiteScore: 2)
Aristotelian Society Supplementary Volume     Hybrid Journal   (Followers: 3)
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Astronomy & Geophysics     Hybrid Journal   (Followers: 43, SJR: 0.146, CiteScore: 0)
Behavioral Ecology     Hybrid Journal   (Followers: 52, SJR: 1.871, CiteScore: 3)
Bioinformatics     Hybrid Journal   (Followers: 304, SJR: 6.14, CiteScore: 8)
Biology Methods and Protocols     Hybrid Journal  
Biology of Reproduction     Full-text available via subscription   (Followers: 10, SJR: 1.446, CiteScore: 3)
Biometrika     Hybrid Journal   (Followers: 20, SJR: 3.485, CiteScore: 2)
BioScience     Hybrid Journal   (Followers: 29, SJR: 2.754, CiteScore: 4)
Bioscience Horizons : The National Undergraduate Research J.     Open Access   (Followers: 1, SJR: 0.146, CiteScore: 0)
Biostatistics     Hybrid Journal   (Followers: 17, SJR: 1.553, CiteScore: 2)
BJA : British J. of Anaesthesia     Hybrid Journal   (Followers: 166, SJR: 2.115, CiteScore: 3)
BJA Education     Hybrid Journal   (Followers: 64)
Brain     Hybrid Journal   (Followers: 68, SJR: 5.858, CiteScore: 7)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 48, SJR: 2.505, CiteScore: 5)
Briefings in Functional Genomics     Hybrid Journal   (Followers: 3, SJR: 2.15, CiteScore: 3)
British J. for the Philosophy of Science     Hybrid Journal   (Followers: 35, SJR: 2.161, CiteScore: 2)
British J. of Aesthetics     Hybrid Journal   (Followers: 26, SJR: 0.508, CiteScore: 1)
British J. of Criminology     Hybrid Journal   (Followers: 587, SJR: 1.828, CiteScore: 3)
British J. of Social Work     Hybrid Journal   (Followers: 88, SJR: 1.019, CiteScore: 2)
British Medical Bulletin     Hybrid Journal   (Followers: 7, SJR: 1.355, CiteScore: 3)
British Yearbook of Intl. Law     Hybrid Journal   (Followers: 32)
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 4, SJR: 1.376, CiteScore: 1)
Cambridge J. of Economics     Hybrid Journal   (Followers: 62, SJR: 0.764, CiteScore: 2)
Cambridge J. of Regions, Economy and Society     Hybrid Journal   (Followers: 11, SJR: 2.438, CiteScore: 4)
Cambridge Quarterly     Hybrid Journal   (Followers: 9, SJR: 0.104, CiteScore: 0)
Capital Markets Law J.     Hybrid Journal   (Followers: 2, SJR: 0.222, CiteScore: 0)
Carcinogenesis     Hybrid Journal   (Followers: 2, SJR: 2.135, CiteScore: 5)
Cardiovascular Research     Hybrid Journal   (Followers: 14, SJR: 3.002, CiteScore: 5)
Cerebral Cortex     Hybrid Journal   (Followers: 45, SJR: 3.892, CiteScore: 6)
CESifo Economic Studies     Hybrid Journal   (Followers: 17, SJR: 0.483, CiteScore: 1)
Chemical Senses     Hybrid Journal   (Followers: 1, SJR: 1.42, CiteScore: 3)
Children and Schools     Hybrid Journal   (Followers: 5, SJR: 0.246, CiteScore: 0)
Chinese J. of Comparative Law     Hybrid Journal   (Followers: 4, SJR: 0.412, CiteScore: 0)
Chinese J. of Intl. Law     Hybrid Journal   (Followers: 23, SJR: 0.329, CiteScore: 0)
Chinese J. of Intl. Politics     Hybrid Journal   (Followers: 9, SJR: 1.392, CiteScore: 2)
Christian Bioethics: Non-Ecumenical Studies in Medical Morality     Hybrid Journal   (Followers: 10, SJR: 0.183, CiteScore: 0)
Classical Receptions J.     Hybrid Journal   (Followers: 26, SJR: 0.123, CiteScore: 0)
Clean Energy     Open Access   (Followers: 1)
Clinical Infectious Diseases     Hybrid Journal   (Followers: 65, SJR: 5.051, CiteScore: 5)
Clinical Kidney J.     Open Access   (Followers: 3, SJR: 1.163, CiteScore: 2)
Communication Theory     Hybrid Journal   (Followers: 22, SJR: 2.424, CiteScore: 3)
Communication, Culture & Critique     Hybrid Journal   (Followers: 26, SJR: 0.222, CiteScore: 1)
Community Development J.     Hybrid Journal   (Followers: 27, SJR: 0.268, CiteScore: 1)
Computer J.     Hybrid Journal   (Followers: 9, SJR: 0.319, CiteScore: 1)
Conservation Physiology     Open Access   (Followers: 2, SJR: 1.818, CiteScore: 3)
Contemporary Women's Writing     Hybrid Journal   (Followers: 9, SJR: 0.121, CiteScore: 0)
Contributions to Political Economy     Hybrid Journal   (Followers: 5, SJR: 0.906, CiteScore: 1)
Critical Values     Full-text available via subscription  
Current Developments in Nutrition     Open Access   (Followers: 1)
Current Legal Problems     Hybrid Journal   (Followers: 27)
Current Zoology     Full-text available via subscription   (Followers: 2, SJR: 1.164, CiteScore: 2)
Database : The J. of Biological Databases and Curation     Open Access   (Followers: 8, SJR: 1.791, CiteScore: 3)
Digital Scholarship in the Humanities     Hybrid Journal   (Followers: 14, SJR: 0.259, CiteScore: 1)
Diplomatic History     Hybrid Journal   (Followers: 20, SJR: 0.45, CiteScore: 1)
DNA Research     Open Access   (Followers: 5, SJR: 2.866, CiteScore: 6)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 4)
Early Music     Hybrid Journal   (Followers: 15, SJR: 0.139, CiteScore: 0)
Economic Policy     Hybrid Journal   (Followers: 39, SJR: 3.584, CiteScore: 3)
ELT J.     Hybrid Journal   (Followers: 24, SJR: 0.942, CiteScore: 1)
English Historical Review     Hybrid Journal   (Followers: 52, SJR: 0.612, CiteScore: 1)
English: J. of the English Association     Hybrid Journal   (Followers: 14, SJR: 0.1, CiteScore: 0)
Environmental Entomology     Full-text available via subscription   (Followers: 11, SJR: 0.818, CiteScore: 2)
Environmental Epigenetics     Open Access   (Followers: 3)
Environmental History     Hybrid Journal   (Followers: 27, SJR: 0.408, CiteScore: 1)
EP-Europace     Hybrid Journal   (Followers: 2, SJR: 2.748, CiteScore: 4)
Epidemiologic Reviews     Hybrid Journal   (Followers: 9, SJR: 4.505, CiteScore: 8)
ESHRE Monographs     Hybrid Journal  
Essays in Criticism     Hybrid Journal   (Followers: 17, SJR: 0.113, CiteScore: 0)
European Heart J.     Hybrid Journal   (Followers: 57, SJR: 9.315, CiteScore: 9)
European Heart J. - Cardiovascular Imaging     Hybrid Journal   (Followers: 9, SJR: 3.625, CiteScore: 3)
European Heart J. - Cardiovascular Pharmacotherapy     Full-text available via subscription   (Followers: 1)
European Heart J. - Quality of Care and Clinical Outcomes     Hybrid Journal  
European Heart J. : Case Reports     Open Access  
European Heart J. Supplements     Hybrid Journal   (Followers: 8, SJR: 0.223, CiteScore: 0)
European J. of Cardio-Thoracic Surgery     Hybrid Journal   (Followers: 9, SJR: 1.681, CiteScore: 2)
European J. of Intl. Law     Hybrid Journal   (Followers: 188, SJR: 0.694, CiteScore: 1)
European J. of Orthodontics     Hybrid Journal   (Followers: 4, SJR: 1.279, CiteScore: 2)
European J. of Public Health     Hybrid Journal   (Followers: 20, SJR: 1.36, CiteScore: 2)
European Review of Agricultural Economics     Hybrid Journal   (Followers: 10, SJR: 1.172, CiteScore: 2)
European Review of Economic History     Hybrid Journal   (Followers: 29, SJR: 0.702, CiteScore: 1)
European Sociological Review     Hybrid Journal   (Followers: 40, SJR: 2.728, CiteScore: 3)
Evolution, Medicine, and Public Health     Open Access   (Followers: 11)
Family Practice     Hybrid Journal   (Followers: 15, SJR: 1.018, CiteScore: 2)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 12, SJR: 1.492, CiteScore: 4)
Fems Microbiology Letters     Hybrid Journal   (Followers: 24, SJR: 0.79, CiteScore: 2)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 30, SJR: 7.063, CiteScore: 13)
Fems Yeast Research     Hybrid Journal   (Followers: 14, SJR: 1.308, CiteScore: 3)
Food Quality and Safety     Open Access   (Followers: 1)
Foreign Policy Analysis     Hybrid Journal   (Followers: 24, SJR: 1.425, CiteScore: 1)
Forest Science     Hybrid Journal   (Followers: 7, SJR: 0.89, CiteScore: 2)
Forestry: An Intl. J. of Forest Research     Hybrid Journal   (Followers: 16, SJR: 1.133, CiteScore: 3)
Forum for Modern Language Studies     Hybrid Journal   (Followers: 6, SJR: 0.104, CiteScore: 0)
French History     Hybrid Journal   (Followers: 33, SJR: 0.118, CiteScore: 0)
French Studies     Hybrid Journal   (Followers: 20, SJR: 0.148, CiteScore: 0)
French Studies Bulletin     Hybrid Journal   (Followers: 10, SJR: 0.152, CiteScore: 0)
Gastroenterology Report     Open Access   (Followers: 2)
Genome Biology and Evolution     Open Access   (Followers: 12, SJR: 2.578, CiteScore: 4)
Geophysical J. Intl.     Hybrid Journal   (Followers: 35, SJR: 1.506, CiteScore: 3)
German History     Hybrid Journal   (Followers: 22, SJR: 0.161, CiteScore: 0)
GigaScience     Open Access   (Followers: 4, SJR: 5.022, CiteScore: 7)
Global Summitry     Hybrid Journal   (Followers: 1)
Glycobiology     Hybrid Journal   (Followers: 14, SJR: 1.493, CiteScore: 3)
Health and Social Work     Hybrid Journal   (Followers: 56, SJR: 0.388, CiteScore: 1)
Health Education Research     Hybrid Journal   (Followers: 15, SJR: 0.854, CiteScore: 2)
Health Policy and Planning     Hybrid Journal   (Followers: 24, SJR: 1.512, CiteScore: 2)
Health Promotion Intl.     Hybrid Journal   (Followers: 22, SJR: 0.812, CiteScore: 2)
History Workshop J.     Hybrid Journal   (Followers: 31, SJR: 1.278, CiteScore: 1)
Holocaust and Genocide Studies     Hybrid Journal   (Followers: 28, SJR: 0.105, CiteScore: 0)
Human Communication Research     Hybrid Journal   (Followers: 13, SJR: 2.146, CiteScore: 3)
Human Molecular Genetics     Hybrid Journal   (Followers: 8, SJR: 3.555, CiteScore: 5)
Human Reproduction     Hybrid Journal   (Followers: 71, SJR: 2.643, CiteScore: 5)
Human Reproduction Open     Open Access  
Human Reproduction Update     Hybrid Journal   (Followers: 19, SJR: 5.317, CiteScore: 10)
Human Rights Law Review     Hybrid Journal   (Followers: 56, SJR: 0.756, CiteScore: 1)
ICES J. of Marine Science: J. du Conseil     Hybrid Journal   (Followers: 53, SJR: 1.591, CiteScore: 3)
ICSID Review     Hybrid Journal   (Followers: 10)
ILAR J.     Hybrid Journal   (Followers: 2, SJR: 1.732, CiteScore: 4)
IMA J. of Applied Mathematics     Hybrid Journal   (SJR: 0.679, CiteScore: 1)
IMA J. of Management Mathematics     Hybrid Journal   (SJR: 0.538, CiteScore: 1)
IMA J. of Mathematical Control and Information     Hybrid Journal   (Followers: 2, SJR: 0.496, CiteScore: 1)
IMA J. of Numerical Analysis - advance access     Hybrid Journal   (SJR: 1.987, CiteScore: 2)
Industrial and Corporate Change     Hybrid Journal   (Followers: 10, SJR: 1.792, CiteScore: 2)
Industrial Law J.     Hybrid Journal   (Followers: 35, SJR: 0.249, CiteScore: 1)
Inflammatory Bowel Diseases     Hybrid Journal   (Followers: 44, SJR: 2.511, CiteScore: 4)
Information and Inference     Free  
Integrative and Comparative Biology     Hybrid Journal   (Followers: 8, SJR: 1.319, CiteScore: 2)
Interacting with Computers     Hybrid Journal   (Followers: 11, SJR: 0.292, CiteScore: 1)
Interactive CardioVascular and Thoracic Surgery     Hybrid Journal   (Followers: 7, SJR: 0.762, CiteScore: 1)
Intl. Affairs     Hybrid Journal   (Followers: 61, SJR: 1.505, CiteScore: 3)
Intl. Data Privacy Law     Hybrid Journal   (Followers: 25)
Intl. Health     Hybrid Journal   (Followers: 6, SJR: 0.851, CiteScore: 2)
Intl. Immunology     Hybrid Journal   (Followers: 3, SJR: 2.167, CiteScore: 4)
Intl. J. for Quality in Health Care     Hybrid Journal   (Followers: 37, SJR: 1.348, CiteScore: 2)
Intl. J. of Constitutional Law     Hybrid Journal   (Followers: 63, SJR: 0.601, CiteScore: 1)
Intl. J. of Epidemiology     Hybrid Journal   (Followers: 226, SJR: 3.969, CiteScore: 5)
Intl. J. of Law and Information Technology     Hybrid Journal   (Followers: 5, SJR: 0.202, CiteScore: 1)
Intl. J. of Law, Policy and the Family     Hybrid Journal   (Followers: 26, SJR: 0.223, CiteScore: 1)
Intl. J. of Lexicography     Hybrid Journal   (Followers: 9, SJR: 0.285, CiteScore: 1)
Intl. J. of Low-Carbon Technologies     Open Access   (Followers: 1, SJR: 0.403, CiteScore: 1)
Intl. J. of Neuropsychopharmacology     Open Access   (Followers: 3, SJR: 1.808, CiteScore: 4)
Intl. J. of Public Opinion Research     Hybrid Journal   (Followers: 10, SJR: 1.545, CiteScore: 1)
Intl. J. of Refugee Law     Hybrid Journal   (Followers: 35, SJR: 0.389, CiteScore: 1)
Intl. J. of Transitional Justice     Hybrid Journal   (Followers: 11, SJR: 0.724, CiteScore: 2)
Intl. Mathematics Research Notices     Hybrid Journal   (Followers: 1, SJR: 2.168, CiteScore: 1)
Intl. Political Sociology     Hybrid Journal   (Followers: 37, SJR: 1.465, CiteScore: 3)
Intl. Relations of the Asia-Pacific     Hybrid Journal   (Followers: 23, SJR: 0.401, CiteScore: 1)
Intl. Studies Perspectives     Hybrid Journal   (Followers: 9, SJR: 0.983, CiteScore: 1)
Intl. Studies Quarterly     Hybrid Journal   (Followers: 45, SJR: 2.581, CiteScore: 2)
Intl. Studies Review     Hybrid Journal   (Followers: 24, SJR: 1.201, CiteScore: 1)
ISLE: Interdisciplinary Studies in Literature and Environment     Hybrid Journal   (Followers: 2, SJR: 0.15, CiteScore: 0)
ITNOW     Hybrid Journal   (Followers: 1, SJR: 0.103, CiteScore: 0)
J. of African Economies     Hybrid Journal   (Followers: 15, SJR: 0.533, CiteScore: 1)
J. of American History     Hybrid Journal   (Followers: 46, SJR: 0.297, CiteScore: 1)
J. of Analytical Toxicology     Hybrid Journal   (Followers: 14, SJR: 1.065, CiteScore: 2)
J. of Antimicrobial Chemotherapy     Hybrid Journal   (Followers: 15, SJR: 2.419, CiteScore: 4)
J. of Antitrust Enforcement     Hybrid Journal   (Followers: 1)
J. of Applied Poultry Research     Hybrid Journal   (Followers: 4, SJR: 0.585, CiteScore: 1)
J. of Biochemistry     Hybrid Journal   (Followers: 40, SJR: 1.226, CiteScore: 2)
J. of Burn Care & Research     Hybrid Journal   (Followers: 9, SJR: 0.768, CiteScore: 2)
J. of Chromatographic Science     Hybrid Journal   (Followers: 18, SJR: 0.36, CiteScore: 1)
J. of Church and State     Hybrid Journal   (Followers: 11, SJR: 0.139, CiteScore: 0)
J. of Communication     Hybrid Journal   (Followers: 53, SJR: 4.411, CiteScore: 5)
J. of Competition Law and Economics     Hybrid Journal   (Followers: 35, SJR: 0.33, CiteScore: 0)
J. of Complex Networks     Hybrid Journal   (Followers: 2, SJR: 1.05, CiteScore: 4)
J. of Computer-Mediated Communication     Open Access   (Followers: 26, SJR: 2.961, CiteScore: 6)
J. of Conflict and Security Law     Hybrid Journal   (Followers: 12, SJR: 0.402, CiteScore: 0)
J. of Consumer Research     Full-text available via subscription   (Followers: 45, SJR: 5.856, CiteScore: 5)

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Journal Cover
Publications of the Astronomical Society of Japan
Journal Prestige (SJR): 0.877
Citation Impact (citeScore): 1
Number of Followers: 3  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0004-6264 - ISSN (Online) 2053-051X
Published by Oxford University Press Homepage  [396 journals]
  • On the colour variations of negative superhumps
    • Authors: Imada A; Yanagisawa K, Kawai N.
      Abstract: We present simultaneous g΄, Rc, and Ic photometry of the notable dwarf nova ER UMa during the 2011 season. Our photometry revealed that the brightness maxima of negative superhumps coincide with the bluest peaks in g΄ − Ic colour variations. We also found that the amplitudes of negative superhumps are the largest in the g΄ band. These observed properties are significantly different from those observed in early and positive superhumps. Our findings are consistent with a tilted disk model as the light source of negative superhumps.
      PubDate: Tue, 19 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy068
      Issue No: Vol. 70, No. 4 (2018)
  • Infrared spectro-polarimeter on the Solar Flare Telescope at NAOJ/Mitaka
    • Authors: Sakurai T; Hanaoka Y, Arai T, et al.
      First page: 58
      Abstract: An infrared spectro-polarimeter installed on the Solar Flare Telescope at the Mitaka headquarters of the National Astronomical Observatory of Japan is described. The new spectro-polarimeter observes the full Sun via slit scans performed at two wavelength bands, one near 1565 nm for a Zeeman-sensitive spectral line of Fe i and the other near 1083 nm for He i and Si i lines. The full Stokes profiles are recorded; the Fe i and Si i lines give information on photospheric vector magnetic fields, and the helium line is suitable for deriving chromospheric magnetic fields. The infrared detector we are using is an InGaAs camera with 640 × 512 pixels and a read-out speed of 90 frames s−1. The solar disk is covered by two swaths (the northern and southern hemispheres) of 640 pixels each. The final magnetic maps are made of 1200 × 1200 pixels with a pixel size of $1{^{\prime\prime}_{.}}8$. We have been carrying out regular observations since 2010 April, and have provided full-disk, full-Stokes maps, at the rate of a few maps per day, on the internet.
      PubDate: Sat, 30 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy050
      Issue No: Vol. 70, No. 4 (2018)
  • Planets around the evolved stars 24 Boötis and γ Libra: A 30
           d-period planet and a double giant-planet system in possible 7:3 MMR
    • Authors: Takarada T; Sato B, Omiya M, et al.
      First page: 59
      Abstract: We report the detection of planets around two evolved giant stars from radial velocity measurements at Okayama Astrophysical observatory. 24 Boo (G3 IV) has a mass of $0.99\,M_{\odot }$, a radius of $10.64\,R_{\odot }$, and a metallicity of [Fe/H] = −0.77. The star hosts one planet with a minimum mass of 0.91 MJup and an orbital period of 30.35 d. The planet has one of the shortest orbital periods among those ever found around evolved stars using radial-velocity methods. The stellar radial velocities show additional periodicity with 150 d, which can probably be attributed to stellar activity. The star is one of the lowest-metallicity stars orbited by planets currently known. γ Lib (K0 III) is also a metal-poor giant with a mass of $1.47\,M_{\odot }$, a radius of $11.1\,R_{\odot }$, and [Fe/H] = −0.30. The star hosts two planets with minimum masses of 1.02 MJup and 4.58 MJup, and periods of 415 d and 964 d, respectively. The star has the second-lowest metallicity among the giant stars hosting more than two planets. Dynamical stability analysis for the γ Lib system sets the minimum orbital inclination angle to be about 70° and suggests that the planets are in 7:3 mean-motion resonance, though the current best-fitting orbits for the radial-velocity data are not totally regular.
      PubDate: Fri, 25 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy052
      Issue No: Vol. 70, No. 4 (2018)
  • Search for companions in visual binary systems using precise
           radial-velocity measurements
    • Authors: Katoh N; Itoh Y, Sato B.
      First page: 60
      Abstract: The frequency of triple and quadruple systems is considered to be high in the early phase of star formation. Some multiple systems decay in the pre-main-sequence phase. The multiplicity of main-sequence stars provides clues about the evolution of binary systems. This work searched for companions of five components of visual binary systems using precise radial-velocity measurements. Their radial velocities were monitored from 2007 to 2012 using the HIgh Dispersion Echelle Spectrograph (HIDES) installed on the Okayama Astrophysical Observatory (OAO) 1.88 m reflector. In combination with previous work, this work searched for companions with an orbital period of less than 9 yr for the five bodies. We found periodic variations in the radial velocities for ADS 6190 A and BDS 10966A. The radial velocities of ADS 7311 A, 31 Dra A, and 31 Dra B show significant trends. ADS 6190 A is an SB1 binary with an orbital period of 366.2 d. The minimum mass of the secondary star is 0.5$^{+0.7}_{-0.2}\,M_{\odot }$. The radial velocity of ADS 7311 A was monitored for an observational span of 3200 d. We rejected a planetary-mass companion as the cause of a decreasing trend in the radial velocity of ADS 7311 A. This work confirmed that the periodic variation in the radial velocity of BDS 10966 A is 771.1 d. Bisector analysis did not reveal a correlation between the asymmetry of a spectral line and the radial velocity of BDS 10966 A. We rejected nonradial oscillation of the photosphere as the source of the radial velocity variation. The variation may be caused by the rotational modulation owing to surface inhomogeneity. The orbital elements of 31 Dra A derived in this paper are consistent with those in a previous paper. 31 Dra A system is an SB1 binary with a minimum mass ratio of 0.30 ± 0.08. 31 Dra B exhibits a periodic variation in radial velocity. The orbital elements derived in this work are consistent with those reported previously by others. The variation is caused by a circumstellar planet.
      PubDate: Thu, 31 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy054
      Issue No: Vol. 70, No. 4 (2018)
  • Orbital solution leading to an acceptable interpretation for the enigmatic
           gamma-ray binary HESS J0632+057
    • Authors: Yuki M; Kawano T, Chimasu S, et al.
      First page: 61
      Abstract: High-dispersion spectroscopic monitoring of HESS J0632+057 has been carried out over four orbital cycles in order to search for orbital modulation, covering the entire orbital phase. We have measured the radial velocity of the Hα emission line with the method introduced by Shafter, Szkody, and Thorstensen (1986, ApJ, 308, 765), which has been successfully applied to some Be stars. The velocity is seen to increase much earlier than expected for the orbital period of 315 d, and much more steeply than expected at around “apastron.” The period of the Hα modulation is found to be $308^{+26}_{-23}$ d. We have also analyzed Swift/XRT data from 2009 to 2015 to study the orbital modulation, selecting the data with good statistics (≥30 counts). With additional two-year data to the previous works, the orbital period has been updated to $313^{+11}_{-8}$ d, which is consistent with the previous X-ray periods and the spectroscopic one. Previous XMM-Newton and Chandra observations prefer a period of 313 d. With the new period, assuming that Hα velocities accurately trace the motion of the Be star, we have derived a new set of orbital parameters. In the new orbit, which is less eccentric (e ≃ 0.6), two outbursts occur: after apastron and just after periastron. Also, the column density in bright phase ($4.7^{+0.9}_{-08}\times 10^{21} \, \mathrm{cm}^{-2}$) is higher than in faint phase (2.2 ± 0.5 × 1021 cm−2). These facts suggest that outbursts occur when the compact object passes nearby/through the Be disk. The mass function implies that the mass of the compact object is less than 2.5 M⊙, assuming that the mass of the Be star is 13.2–18.2 M⊙ (Aragona et al. 2010, ApJ, 724, 306), unless the inclination is extremely small. The photon index indicates that the spectra become softer when the system is bright. These suggest that the compact object is a pulsar.
      PubDate: Tue, 22 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy053
      Issue No: Vol. 70, No. 4 (2018)
  • Time-resolved spectroscopic observations of an M-dwarf flare star EV
           Lacertae during a flare
    • Authors: Honda S; Notsu Y, Namekata K, et al.
      First page: 62
      Abstract: We have performed five night spectroscopic observations of the Hα line of EV Lac with a medium wavelength resolution (R ∼ 10000) using the 2 m Nayuta telescope at the Nishi-Harima Astronomical Observatory. EV Lac always possesses the Hα emission line; however, its intensity was stronger on 2015 August 15 than during the other four night periods. On this night, we observed a rapid rise (∼20 min) and a subsequent slow decrease (∼1.5 hr) of the emission-line intensity of Hα, which was probably caused by a flare. We also found an asymmetrical change in the Hα line on the same night. The enhancement has been observed in the blue wing of the Hα line during each phase of this flare (from the flare start to the flare end), and absorption components were present in its red wing during the early and later phases of the flare. Such blue enhancement (blue asymmetry) of the Hα line is sometimes seen during solar flares, but only during the early phases. Even for solar flares, little is known about the origin of the blue asymmetry. Compared with solar flare models, the presented results can lead to better understanding of the dynamics of stellar flares.
      PubDate: Fri, 18 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy055
      Issue No: Vol. 70, No. 4 (2018)
  • Sunspot drawings by Japanese official astronomers in 1749–1750
    • Authors: Hayakawa H; Iwahashi K, Fujiyama M, et al.
      First page: 63
      Abstract: Sunspot observations with telescopes in the 18th century were carried out in Japan as well as elsewhere. One of these sunspot observations is recorded in an account called Sansaizusetsu narabini Kansei irai Jissoku Zusetsu (Charts of Three Worlds and Diagrams of Actual Observations since Kansei Era). We have analyzed manuscripts of this account to show a total of 15 sunspot drawings during 1749–1750. These observations are considered to be carried out by contemporary official astronomers in Japan, with telescopes covered by zongurasus (< zonglas in Dutch, corresponding to “sunglass” in English). We counted their group number of sunspots to locate them in long-term solar activity and show that their observations were situated near the solar maximum in 1750. We also computed their locations and areas, while we have to admit differences of the variant manuscripts with one another. These observational records show the spread of sunspot observations not only in Europe, but also in Japan, and hence may contribute to crosscheck, or possibly to improve the known sunspot indices.
      PubDate: Wed, 11 Jul 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy066
      Issue No: Vol. 70, No. 4 (2018)
  • Over a thousand new periodic orbits of a planar three-body system with
           unequal masses
    • Authors: Li X; Jing Y, Liao S.
      First page: 64
      Abstract: The three-body problem is common in astronomy, examples of which are the solar system, exoplanets, and stellar systems. Due to its chaotic characteristic, discovered by Poincaré, only three families of periodic three-body orbits were found in 300 years, until 2013 when Šuvakov and Dmitrašinović (2013, Phys. Rev. Lett., 110, 114301) found 13 new periodic orbits of a Newtonian planar three-body problem with equal mass. Recently, more than 600 new families of periodic orbits of triple systems with equal mass were found by Li and Liao (2017, Sci. China-Phys. Mech. Astron., 60, 129511). Here, we report 1349 new families of planar periodic orbits of the triple system where two bodies have the same mass and the other has a different mass. None of the families have ever been reported, except the famous “figure-eight” family. In particular, 1223 among these 1349 families are entirely new, i.e., with newly found “free group elements” that have been never reported, even for three-body systems with equal mass. It has been traditionally believed that triple systems are often unstable if they are non-hierarchical. However, all of our new periodic orbits are in non-hierarchical configurations, but many of them are either linearly or marginally stable. This might inspire the long-term astronomical observation of stable non-hierarchical triple systems in practice. In addition, using these new periodic orbits as initial guesses, new periodic orbits of triple systems with three unequal masses can be found by means of the continuation method, which is more general and thus should have practical meaning from an astronomical viewpoint.
      PubDate: Mon, 21 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy057
      Issue No: Vol. 70, No. 4 (2018)
  • ALMA deep field in SSA22: Survey design and source catalog of a
           20 arcmin2 survey at 1.1 mm
    • Authors: Umehata H; Hatsukade B, Smail I, et al.
      First page: 65
      Abstract: To search for dust-obscured star-formation activity in the early Universe, it is essential to obtain a deep and wide submillimeter/millimeter map. The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled us to obtain such maps with sufficiently high spatial resolution to be free from source confusion. We present a new 1.1 mm-wave map obtained by ALMA in the SSA22 field. The field contains a remarkable proto-cluster at z = 3.09; therefore, it is an ideal region to investigate the role of a large-scale cosmic web on dust-obscured star formation. The typical 1σ depth of our map is 73 μJy beam−1 with a ${0^{^{\prime\prime}_{.}}5}$ resolution. Combining the present survey with earlier, archived observations, we map an area of 20 arcmin2 (71 comoving Mpc2 at z = 3.09). Within the combined survey area we have detected 35 sources at a signal-to-noise ratio (S/N) >5, with flux densities of S1.1mm = 0.43–5.6 mJy, equivalent to star-formation rates of ≳100–1000 M⊙ yr−1 at z = 3.09, for a Chabrier initial mass function: 17 sources out of 35 are new detections. The cumulative number counts show an excess by a factor of three to five compared to blank fields. The excess suggests enhanced, dust-enshrouded star-formation activity in the proto-cluster on a 10 comoving Mpc scale, indicating accelerated galaxy evolution in this overdense region.
      PubDate: Fri, 01 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy065
      Issue No: Vol. 70, No. 4 (2018)
  • Hyper Suprime-Cam: Filters
    • Authors: Kawanomoto S; Uraguchi F, Komiyama Y, et al.
      First page: 66
      Abstract: We describe five broad-band filters and a narrow-band one for the Hyper Suprime-Cam (HSC) at the prime focus of the Subaru Telescope. Since the HSC is a practical successor to the Suprime-Cam (SC), our broad-band filter set follows the SC's SDSS g΄, r΄, i΄, z΄ filters, and Y filter, and the Hα filter is adopted as our first narrow-band filter. Filters for the HSC are quite large; therefore, they are constructed only by interference coatings. Based on a draft specification guided by that of SC's filters, we made prototype filters which were evaluated at a laboratory, and eventually used them in the actual HSC commissioning observation. Through this process, we learned that transmission measurement with a fine spatial sampling was crucial for reliable understanding of the filter characteristics, and this motivated us to develop an efficient measurement system. Since this measurement system is placed in the summit facility and functions semi-automatically, long-term monitoring of the performance of HSC filters will be achieved. We present in this paper the specifications that the HSC filter should meet, problems and solutions in filter implementation, issues found through the commissioning observing run, the new filter measurement system at the summit facility, and transmission curves and tables of the filters.
      PubDate: Wed, 27 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy056
      Issue No: Vol. 70, No. 4 (2018)
  • State transitions of GRS 1739−278 in the 2014 outburst
    • Authors: Wang S; Kawai N, Shidatsu M, et al.
      First page: 67
      Abstract: We report on the X-ray spectral analysis and time evolution of GRS 1739−278 during its 2014 outburst, based on MAXI/GSC and Swift/XRT observations. Over the course of the outburst, a transition from the low/hard state to the high/soft state and then back to the low/hard state was seen. During the high/soft state, the innermost disk temperature mildly decreased, while the innermost radius estimated with the multi-color disk model remained constant at ∼18 (D/8.5 kpc)(cos i/cos 30°)−1/2 km, where D is the source distance and i is the inclination of observation. This small innermost radius of the accretion disk suggests that the central object is more likely to be a Kerr black hole rather than a Schwardzschild black hole. Applying a relativistic disk emission model to the high/soft state spectra, a mass upper limit of 18.3 M⊙ was obtained based on the inclination limit i < 60° for an assumed distance of 8.5 kpc. Using the empirical relation of the transition luminosity to the Eddington limit, the mass is constrained to 4.0–18.3 M⊙ for the same distance. The mass can be further constrained to be no larger than 9.5 M⊙ by adopting the constraints based on the fits to the NuSTAR spectra with relativistically blurred disk reflection models (Miller et al. 2015, ApJ, 799, L6).
      PubDate: Fri, 25 May 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy058
      Issue No: Vol. 70, No. 4 (2018)
  • Membership determination of open clusters based on a spectral clustering
    • Authors: Gao X.
      First page: 68
      Abstract: We present a spectral clustering (SC) method aimed at segregating reliable members of open clusters in multi-dimensional space. The SC method is a non-parametric clustering technique that performs cluster division using eigenvectors of the similarity matrix; no prior knowledge of the clusters is required. This method is more flexible in dealing with multi-dimensional data compared to other methods of membership determination. We use this method to segregate the cluster members of five open clusters (Hyades, Coma Ber, Pleiades, Praesepe, and NGC 188) in five-dimensional space; fairly clean cluster members are obtained. We find that the SC method can capture a small number of cluster members (weak signal) from a large number of field stars (heavy noise). Based on these cluster members, we compute the mean proper motions and distances for the Hyades, Coma Ber, Pleiades, and Praesepe clusters, and our results are in general quite consistent with the results derived by other authors. The test results indicate that the SC method is highly suitable for segregating cluster members of open clusters based on high-precision multi-dimensional astrometric data such as Gaia data.
      PubDate: Fri, 08 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy059
      Issue No: Vol. 70, No. 4 (2018)
  • Structure of the Milky Way stellar halo out to its outer boundary with
           blue horizontal-branch stars
    • Authors: Fukushima T; Chiba M, Homma D, et al.
      First page: 69
      Abstract: We present the structure of the Milky Way stellar halo beyond Galactocentric distances of r = 50 kpc traced by blue horizontal-branch (BHB) stars, which are extracted from the survey data in the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). We select BHB candidates based on (g, r, i, z) photometry, where the z-band is on the Paschen series and the colors that involve the z-band are sensitive to surface gravity. About 450 BHB candidates are identified between r = 50 kpc and 300 kpc, most of which are beyond the reach of previous large surveys, including the Sloan Digital Sky Survey. We find that the global structure of the stellar halo in this range has substructures, which are especially remarkable in the GAMA15H and XMM-LSS fields in the HSC-SSP. We find that the stellar halo can be fitted to a single power-law density profile with an index of α ≃ 3.3 (3.5) with (without) these fields and its global axial ratio is q ≃ 2.2 (1.3). Thus, the stellar halo may be significantly disturbed and be made in a prolate form by halo substructures, perhaps associated with the Sagittarius stream in its extension beyond r ∼ 100 kpc. For a broken power-law model allowing different power-law indices inside/outside a break radius, we obtain a steep power-law slope of α ≃ 5 outside a break radius of ∼100 kpc (200 kpc) for the case with (without) GAMA15H and XMM-LSS. This radius of 200 kpc might be as close as a halo boundary if there is any, although a larger BHB sample is required from further HSC-SSP surveys to increase its statistical significance.
      PubDate: Fri, 01 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy060
      Issue No: Vol. 70, No. 4 (2018)
  • Fortran interface layer of the framework for developing particle simulator
    • Authors: Namekata D; Iwasawa M, Nitadori K, et al.
      First page: 70
      Abstract: Numerical simulations based on particle methods have been widely used in various fields including astrophysics. To date, various versions of simulation software have been developed by individual researchers or research groups in each field, through a huge amount of time and effort, even though the numerical algorithms used are very similar. To improve the situation, we have developed a framework, called FDPS (Framework for Developing Particle Simulators), which enables researchers to develop massively parallel particle simulation codes for arbitrary particle methods easily. Until version 3.0, FDPS provided an API (application programming interface) for the C++ programming language only. This limitation comes from the fact that FDPS is developed using the template feature in C++, which is essential to support arbitrary data types of particle. However, there are many researchers who use Fortran to develop their codes. Thus, the previous versions of FDPS require such people to invest much time to learn C++. This is inefficient. To cope with this problem, we developed a Fortran interface layer in FDPS, which provides API for Fortran. In order to support arbitrary data types of particle in Fortran, we design the Fortran interface layer as follows. Based on a given derived data type in Fortran representing particle, a Python script provided by us automatically generates a library that manipulates the C++ core part of FDPS. This library is seen as a Fortran module providing an API of FDPS from the Fortran side and uses C programs internally to interoperate Fortran with C++. In this way, we have overcome several technical issues when emulating a ‘template’ in Fortran. Using the Fortran interface, users can develop all parts of their codes in Fortran. We show that the overhead of the Fortran interface part is sufficiently small and a code written in Fortran shows a performance practically identical to the one written in C++.
      PubDate: Tue, 12 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy062
      Issue No: Vol. 70, No. 4 (2018)
  • Identification and period investigation of pulsation variable star
           UY Camelopardalis, an RR Lyrae star in binary system
    • Authors: Li L; Qian S, Voloshina I, et al.
      First page: 71
      Abstract: We present photometric measurements of the short period variable star UY Cam, which has been classified as a δ Scuti or c-type RR Lyrae (RRc) variable in different catalogs. Based on the analyses on Fourier coefficients and (NUV − V)0, we find that UY Cam is probably an RRc star. We obtain 58 new times of light maximum for UY Cam based on several sky surveys and our observations. Combining these with the times of light maximum in literature, a total of 154 times of light maximum are used to analyze the O − C diagram of UY Cam. The results show that the O − C pattern can be described by a downward parabolic component with a rate of −6.86 ± 0.47 × 10−11 d d−1, and a cyclic variation with a period of 65.7 ± 2.4 yr. We suppose these components are caused by the stellar evolution and the light travel time effect (LiTE) of a companion in elliptical orbit, respectively. By calculation, the minimum mass of the potential companion is about 0.17 M⊙, and its mass should be less than or equal to the pulsation primary star when the inclination $i > {22{^{\circ}_{.}}5}$. Therefore, the companion should be a low-mass star, like a late-type main-sequence star or a white dwarf. Due to the unique property of UY Cam, we suggest that more observations and studies on UY Cam and other RRc stars are needed to check the nature of these stars, including the pulsations and binarities.
      PubDate: Fri, 01 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy061
      Issue No: Vol. 70, No. 4 (2018)
  • First photometric analysis of magnetic activity and orbital period
           variations for the semi-detached binary BU Vulpeculae
    • Authors: Wang J; Zhang B, Yu J, et al.
      First page: 72
      Abstract: Four sets of multi-color CCD photometric observations of the close binary BU Vul were carried out for four successive months in 2010. From our observations, there are obvious variations and asymmetry of light curves on the timescale of a month, indicating high-level stellar spot activity on the surface of at least one component. The Wilson–Devinney (2010) program was used to determine the photometric solutions, which suggest that BU Vul is a semi-detached binary with the cool, less massive component filling with the critical Roche lobe. The solutions also reveal that the spots on the primary and the secondary have changed and drifted in 2010 July, August, and September. Based on analysis of the O − C curves of BU Vul, its orbital period shows a cyclic oscillation (T3 = 22.4 yr, A3 = 0.0029 d) superimposed on a secular increase. The continuous increase is possibly a result of mass transfer from the less massive component to the more massive one at a rate of dM/dt = −2.95 × 10−9 M⊙ yr−1. The cyclic variation maybe be caused by the presence of a tertiary companion with extremely low luminosity. Combined with the distortions of the light curve on 2009 November 4, we infer that BU Vul has two additional companions in a quadruple system.
      PubDate: Tue, 12 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy064
      Issue No: Vol. 70, No. 4 (2018)
  • ALMA 12CO (J = 1–0) imaging of the nearby galaxy M 83: Variations in
           the efficiency of star formation in giant molecular clouds
    • Authors: Hirota A; Egusa F, Baba J, et al.
      First page: 73
      Abstract: We present results of the 12CO (1–0) mosaic observations of the nearby barred-spiral galaxy M 83 obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). The total flux is recovered by combining the ALMA data with single-dish data obtained using the Nobeyama 45 m telescope. The combined map covers a ∼13 kpc2 field that includes the galactic center, eastern bar, and spiral arm with a resolution of 2${^{\prime\prime}_{.}}$03 × 1${^{\prime\prime}_{.}}$15 (∼45 pc × ∼25 pc). With a resolution comparable to typical sizes of giant molecular clouds (GMCs), the CO distribution in the bar and arm is resolved into many clumpy peaks that form ridge-like structures. Remarkably, in the eastern arm, the CO peaks form two arc-shaped ridges that run along the arm and exhibit a distinct difference in the activity of star formation: the one on the leading side has numerous H ii regions associated with it, whereas the other one on the trailing side has only a few. To see whether GMCs form stars with uniform star formation efficiency (SFE) per free-fall time (SFEff), GMCs are identified from the data cube and then cross-matched with the catalog of ${H}\,\, \small {II}$ regions to estimate the star formation rate for each of them. 179 GMCs with a median mass of 1.6 × 106 M⊙ are identified. The mass-weighted average SFEff of the GMCs is ∼9.4 × 10−3, which is in agreement with models of turbulence regulated star formation. Meanwhile, we find that SFEff is not universal within the mapped region. In particular, one of the arm ridges shows a high SFEff with a mass-weighted value of ∼2.7 × 10−2, which is higher by more than a factor of 5 compared to the inter-arm regions. This large regional variation in SFEff favors the recent interpretation that GMCs do not form stars at a constant rate within their lifetime.
      PubDate: Wed, 27 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy071
      Issue No: Vol. 70, No. 4 (2018)
  • Radial velocity measurements of an orbiting star around Sgr A*
    • Authors: Nishiyama S; Saida H, Takamori Y, et al.
      First page: 74
      Abstract: During the next closest approach of the orbiting star S2/S0-2 to the Galactic supermassive black hole (SMBH), it is estimated that radial velocity (RV) measurements with an uncertainty of a few 10 km s−1 will allow us to detect post-Newtonian effects throughout 2018. To evaluate the best achievable uncertainty in RV and its stability, we carried out near-infrared, high-resolution (R ∼ 20000) spectroscopic monitoring observations of S2 using the Subaru telescope and its near-infrared spectrograph IRCS from 2014 to 2016. Br-γ absorption lines have been detected in the 2015 and 2016 spectra, but have not been clearly detected in the 2014 spectrum. The detected Br-γ absorption lines are used to determine the RVs of S2. The statistical uncertainties are derived using the jackknife analysis, and spectra combined from divided subdata sets. The wavelength calibrations in our three-year monitoring are stable: short-term (hours to days) uncertainties in RVs are ≲ 0.5 km s−1, and the long-term (three years) uncertainty is 1.2 km s−1. We thoroughly analyzed possible sources of systematic uncertainties, such as the incomplete subtraction of OH skylines. The relevant uncertainties are estimated to be less than several km s−1. The final results using the Br-γ line are 877 ± 25 km s−1 in 2015, and 1109 ± 14 km s−1 in 2016. When we use two He i lines at 2.113 μm in addition to Br-γ, the mean RV and its standard error are 1114 km s−1 and 5 km s−1, respectively, in 2016. However, we have found a larger scatter around the expected RV curve with the best-fitting orbiting parameters of S2, implying additional uncertainties not yet considered. The difference between the RVs estimated by Newtonian mechanics and general relativity will reach about 200 km s−1 near the next pericenter passage in 2018. Therefore, in addition to astrometric and spectroscopic data obtained with other telescopes, RV measurements with Subaru in 2018 will form important data sets with which to detect general relativistic effects from the SMBH.
      PubDate: Wed, 27 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy067
      Issue No: Vol. 70, No. 4 (2018)
  • Discovery of recombining plasma from the faintest GeV supernova remnant HB
           21 and a possible scenario for cosmic rays escaping from supernova remnant
    • Authors: Suzuki H; Bamba A, Nakazawa K, et al.
      First page: 75
      Abstract: We present an X-ray study of the GeV gamma-ray supernova remnant (SNR) HB 21 with Suzaku. HB 21 is interacting with molecular clouds, and is the faintest in the GeV band among known GeV SNRs. We discovered strong radiative recombination continua of Si and S from the center of the remnant, which provide direct evidence of a recombining plasma (RP). The total emission can be explained with the RP and ionizing plasma components. The electron temperature and recombination timescale of the RP component were estimated as 0.17 (0.15–0.18) keV and 3.2 (2.0–4.8) × 1011 s cm−3, respectively. The estimated age of the RP (∼170 kyr) is the longest among known recombining GeV SNRs, because of a very low density of electrons (∼0.05 cm−3). We have examined the dependencies of GeV spectral indices on each of RP ages and SNR diameters for nine recombining GeV SNRs. Both showed possible positive correlations, indicating that both the parameters can be good indicators of properties of accelerated protons, for instance the degree of escape from SNR shocks. A possible scenario for a process of proton escape is introduced: interaction with molecular clouds makes weaker magnetic turbulence and cosmic-ray protons escape, simultaneously cooling down the thermal electrons and generating an RP.
      PubDate: Wed, 13 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy069
      Issue No: Vol. 70, No. 4 (2018)
  • MIRIS observation of near-infrared diffuse Galactic light
    • Authors: Onishi Y; Sano K, Matsuura S, et al.
      First page: 76
      Abstract: We report near-infrared (IR) observations of high Galactic latitude clouds to investigate diffuse Galactic light (DGL), which is starlight scattered by interstellar dust grains. The observations were performed at 1.1 and 1.6 μm with a wide-field camera instrument, the Multi-purpose Infra-Red Imaging System (MIRIS) onboard the Korean satellite STSAT-3. The DGL brightness is measured by correlating the near-IR images with a far-IR 100 μm map of interstellar dust thermal emission. The wide-field observation of DGL provides the most accurate DGL measurement achieved to-date. We also find a linear correlation between optical and near-IR DGL in the MBM32 field. To study interstellar dust properties in MBM32, we adopt recent dust models with and without μm-sized very large grains and predict the DGL spectra, taking into account the reddening effect of the interstellar radiation field. The result shows that the observed color of the near-IR DGL is closer to the model spectra without very large grains. This may imply that dust growth in the observed MBM32 field is not active owing to the low density of its interstellar medium.
      PubDate: Fri, 15 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy070
      Issue No: Vol. 70, No. 4 (2018)
  • Spatially resolved spectroscopy of non-thermal X-rays in
           RX J1713.7−3946 with Chandra
    • Authors: Okuno T; Tanaka T, Uchida H, et al.
      First page: 77
      Abstract: The young shell-type supernova remnant (SNR) RX J1713.7−3946 has been studied as a suitable target to test the SNR paradigm for the origin of Galactic cosmic rays. We present a spatially resolved spectroscopy of the non-thermal X-ray emission in RX J1713.7−3946 with Chandra. In order to obtain X-ray properties of the filamentary structures and their surrounding regions, we divide the southeastern (SE), southwestern (SW), and northwestern (NW) parts of the SNR into subregions on the typical order of several 10" and extract spectra from each subregion. Their photon indices are significantly different among the subregions, with a range of 1.8 < Γ < 3. In the SE part, the clear filaments are harder (Γ ∼ 2.0) than the surrounding regions. This is a common feature often observed in young SNRs and naturally interpreted as a consequence of synchrotron cooling. On the other hand, the bright filamentary regions do not necessarily coincide with the hardest regions in the SW and NW parts. We also find the SW filamentary region is relatively rather soft (Γ ∼ 2.7). In addition, we find that hard regions with photon indices of 2.0–2.2 exist around the bright emission although the hard regions lie in the downstream region and the bright emission does not appear to be the blast wave shock front. Both the aforementioned characteristic regions in SW are located close to peaks of the interstellar gas. We discuss possible origins of the spatial variation of the photon indices, paying particular attention to the shock–cloud interactions.
      PubDate: Tue, 19 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy072
      Issue No: Vol. 70, No. 4 (2018)
  • On the nature of long-period dwarf novae with rare and low-amplitude
    • Authors: Kimura M; Kato T, Maehara H, et al.
      First page: 78
      Abstract: There are several peculiar long-period dwarf-nova-like objects that show rare, low-amplitude outbursts with highly ionized emission lines; 1SWASP J162117+441254, BD Pav, and V364 Lib are among them. Some researchers even doubt whether 1SWASP J1621 and V364 Lib have the same nature as normal dwarf novae. We studied the peculiar outbursts in these three objects via our optical photometry and spectroscopy, and performed numerical modeling of their orbital variations to investigate their properties. We found that their outbursts lasted for a long interval (a few tens of days), and that slow rises in brightness were commonly observed during the early stage of their outbursts. Our analyses and numerical modeling suggest that 1SWASP J1621 has a very high inclination, close to 90°, plus a faint hot spot. Although BD Pav seems to have a slightly lower inclination (∼75°), the other properties are similar to those in 1SWASP J1621. On the other hand, V364 Lib appears to have a massive white dwarf, a hot companion star, and a low inclination (∼35°). In addition, these three objects possibly have a low transfer rate and/or large disks originating from the long orbital periods. We found that these properties of the three objects can explain their infrequent and low-amplitude outbursts within the context of the disk instability model in normal dwarf novae without a strong magnetic field. In addition, we suggest that the highly ionized emission lines in outburst are observed due to a high inclination and/or a massive white dwarf. More instances of this class of object may be unrecognized, since their unremarkable outbursts can be easily overlooked.
      PubDate: Wed, 27 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy073
      Issue No: Vol. 70, No. 4 (2018)
  • OAO/MITSuME photometry of dwarf novae. III. CSS130418:174033+414756
    • Authors: Imada A; Isogai K, Yanagisawa K, et al.
      First page: 79
      Abstract: We report on multicolor photometry of the short-period dwarf nova CSS130418:174033+414756 during the 2013 superoutburst. The system showed an unusually short superhump period of 0.046346(67) d during stage A, which is one of the shortest periods among dwarf novae below the period minimum. We found that the bluest peaks in g΄ − Ic color variations tended to coincide with the brightness minima of the superhump modulations. We also studied nightly-averaged superhump amplitudes in the g΄, Rc, and Ic bands and found that they have less dependence on wavelength. These properties are likely to be in common with dwarf novae exhibiting superhumps. We successfully obtained g΄ − Rc and Rc − Ic colors during the temporal dip. The color indices were significantly bluer compared with other dips of WZ Sge-type dwarf novae. By using the period of the growing superhumps, we estimated the mass ratio to be q = 0.077(5), which is much larger than the previous study.
      PubDate: Sat, 30 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy074
      Issue No: Vol. 70, No. 4 (2018)
  • Metal pollution of low-mass Population III stars through accretion of
           interstellar objects like ‘Oumuamua
    • Authors: Tanikawa A; Suzuki T, Doi Y.
      First page: 80
      Abstract: We calculate the accretion mass of interstellar objects (ISOs) like ‘Oumuamua on to low-mass Population III stars (Pop. III survivors), and estimate the surface pollution of Pop. III survivors. The ISO number density estimated from the discovery of ‘Oumuamua is so high (∼0.2 au−3) that Pop. III survivors have chances of colliding with ISOs ≳ 105 times per 1 Gyr. ‘Oumuamua itself would be sublimated near Pop. III survivors, since its size is small; ∼100 m. However, ISOs with size ≳3 km would reach the Pop. III survivor surfaces. Supposing an ISO cumulative number density with size larger than D is n∝D−α, Pop. III survivors can accrete ISO mass ≳10−16 M⊙, or ISO iron mass ≳10−17 M⊙, if α < 4. This iron mass is larger than the accretion mass of interstellar medium (ISM) by several orders of magnitude. Taking into account material mixing in the convection zone of Pop. III survivors, we find that their surface pollution is typically [Fe/H] ≲ −8 in most cases; however, the surface pollution of Pop. III survivors with 0.8 M⊙ can be [Fe/H] ≳ −6 because of the very shallow convective layer. If we consider Pop. III survivors located at the Galactocentric distance of 8 kpc, the dependence of the metal pollution is as follows. If α > 4, Pop. III survivors have no chance at colliding with ISOs with D ≳ 3 km, and remain metal-free. If 3 < α < 4, Pop. III survivors would be most polluted by ISOs up to [Fe/H] ∼ −7. If α < 3 up to D ∼ 10 km, Pop. III survivors could hide in metal-poor stars so far discovered. Pop. III survivors would be more polluted with decreasing Galactocentric distance. Although the metal pollution depends on α and the Galactocentric distance, we first show the importance of ISOs for the metal pollution of Pop. III survivors.
      PubDate: Tue, 03 Jul 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy075
      Issue No: Vol. 70, No. 4 (2018)
  • MAXI upper limits of the electromagnetic counterpart of GW170817
    • Authors: Sugita S; Kawai N, Nakahira S, et al.
      First page: 81
      Abstract: We report on the Monitor of All-sky X-ray Image (MAXI) observation of the gravitational-wave (GW) event GW170817 and the electromagnetic counterpart of GW170817. GW170817 is a binary neutron star coalescence candidate detected by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) and Advanced Virgo detectors, and it is the first event for which the optical counterpart has been discovered. In the MAXI observation, the Gas Slit Camera (GSC) covered approximately 62% of the sky region of the GW event within the 90% probability during the first 92 min orbital period after the trigger. No significant X-ray transient was detected in the error region, and the upper limit of the average flux with a significance of 3σ in the 2–10 keV band was 53/26 mCrab (one-orbit observation/one-day observation). In the optical counterpart of GW170817, the observational window of the GSC at the position started 20 s after the GW trigger, but the high-voltage power supply of the GSC was unfortunately off at the time because the International Space Station (ISS) was entering a high-particle-background region.The first observation of the position by the GSC was eventually performed 16797 s (4.6 hr) after the GW trigger, yielding the 3σ upper limit of 8.60 × 10−9 erg cm−2 s−1 in the 2–10 keV band, though it was the earliest X-ray observation of the counterpart.
      PubDate: Fri, 06 Jul 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy076
      Issue No: Vol. 70, No. 4 (2018)
  • Origin of the low-temperature plasma in the Galactic center X-ray emission
    • Authors: Yamauchi S; Shimizu M, Nobukawa M, et al.
      First page: 82
      Abstract: The Galactic Center X-ray emission (GCXE) is composed of high-temperature (∼7 keV) and low-temperature (∼1 keV) plasmas (HTP and LTP, respectively). The global structure of the HTP is roughly uniform over the Galactic Center (GC) region, and the origin of the HTP has been extensively studied. On the other hand, the LTP is more clumpy, and its origin has not been studied in detail. In the S xv Heα line map, a pair of horn-like soft diffuse sources are seen at symmetric positions with respect to Sagittarius A⋆. The X-ray spectra of the pair are well represented by an absorbed thin thermal plasma model of temperature and NH of 0.6–0.7 keV and 4 × 1022 cm−2, respectively. The NH values indicate that the pair are located near the GC. Then the dynamical time scales of the pair are ∼105 yr. The Si and S abundances and the surface brightnesses in the S xv Heα line band are 0.7–1.2 and 0.6–1.3 solar, and (2.0–2.4) × 10−15 erg s−1 cm−2 arcmin−2, respectively. The temperature, abundances, and surface brightness are similar to those of the LTP in the GCXE, while the abundances are far larger than those of known point sources, typically coronal active stars and RS CVn-type active binaries. Based on these results, the possible origin of the LTP is discussed.
      PubDate: Sat, 30 Jun 2018 00:00:00 GMT
      DOI: 10.1093/pasj/psy077
      Issue No: Vol. 70, No. 4 (2018)
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