Hidetoshi Iwamatsu

Coordinated Multiwavelength Observations of BL Lacertae in 2000

BL Lacertae (BL Lac) was the target of an extensive multiwavelength monitoring campaign in the second half of 2000. Simultaneous or quasi-simultaneous observations were taken at radio (University of Michigan Radio Astronomy Observatory and Metsahovi Radio Telescope) and optical (Whole Earth Blazar Telescope (WEBT) collaboration) frequencies, in X-rays (BeppoSAX and RXTE), and at very high energy gamma rays (HEGRA). The WEBT optical campaign achieved an unprecedented time coverage, virtually continuous over several 10-20 hr segments. It revealed intraday variability on timescales of � 1.5 hr and evidence for spectral hardening associated with increasing optical flux. During the campaign, BL Lac underwent a major transition from a rather quiescent state prior to 2000 September, to a flaring state for the rest of the year. ThisBL Lacertae (BL Lac) was the target of an extensive multiwavelength monitoring campaign in the second half of 2000. Simultaneous or quasi-simultaneous observations were taken at radio (University of Michigan Radio Astronomy Observatory andMetsähovi Radio Telescope) and optical (Whole Earth Blazar Telescope [WEBT] collaboration) frequencies, in X-rays (BeppoSAX and RXTE), and at very high energy gamma rays (HEGRA). The WEBT optical campaign achieved an unprecedented time coverage, virtually continuous over several 10–20 hr segments. It revealed intraday variability on timescales of 1.5 hr and evidence for spectral hardening associated with increasing optical flux. During the campaign, BL Lac underwent a major transition from a rather quiescent state prior to 2000 September, to a flaring state for the rest of the year. This 36 Department of Chemistry, Physics, and Astronomy, FrancisMarionUniversity, P.O. Box 100547, Florence, SC 29501-0547. 37 Department of Physics and Astronomy, University of SouthamptonHighfield, Southampton SO17 1BJ, UK. 38 Dipartimento di Fisica Generale, Università di Torino, Via P. Giuria 1, I-10125 Turin, Italy. 34 Department of Physics and Astronomy,Western KentuckyUniversity, 1 Big RedWay, Bowling Green, KY 42104. 35 Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303. 1 Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701. 2 Department of Astronomy, BostonUniversity, 725 Commonwealth Avenue, Boston,MA 02215. 3 Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807Merate, Italy. 4 IstitutoNazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy. 5 Department of Astronomy, University ofMichigan, 810 Dennison Building, AnnArbor,MI 48109-1090. 6 Metsähovi Radio Observatory, Helsinki University of Technology,Metsähovintie 114, 02540Kylmälä, Finland. 7 Institut für Experimentelle und Angewandte Physik, Universität Kiel, Leibnitzstrasse 15–19, D-24118Kiel, Germany. 8 Max-Planck-Institut für Kernphysik, Postfach 10 39 80, D-69029Heidelberg, Germany. 9 Physics Department,WashingtonUniversity, 1 Brookings Drive, CB 1105, St. Louis, MO 63130. 10 Abastumani Observatory, 383762Abastumani, Georgia. 11 Astrophysikalisches Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany. 12 Landessternwarte Heidelberg-Königstuhl, Königstuhl 12, D-69117Heidelberg, Germany. 13 Ulugh Beg Astronomical Institute, Uzbek Academy of Sciences, Astronomicheskaya 33, Tashkent 700052, Uzbekistan. 14 IsaacNewton Institute of Chile, Uzbekistan Branch. 15 Physics Department, University of Crete, 710 03Heraklion, Crete, Greece. 16 IESL, Foundation for Research and Technology-Hellas, 711 10Heraklion, Crete, Greece. 17 Astronomical Institute, OsakaKyoikuUniversity, Kashiwara-shi, Osaka 582-8582, Japan. 18 Tuorla Observatory, 21500 Piikkiö, Finland. 19 Osservatorio Astronomico, Università di Perugia, Via B. Bonfigli, I-06126 Perugia, Italy. 20 Osservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, Italy. 21 Department of Physics and Astronomy, University of Victoria, BC, Canada. 22 Institute for Astrophysical Research, BostonUniversity, 725 Commonwealth Avenue, Boston,MA 02215. 23 Center for Astrophysics, GuangzhouUniversity, Guangzhou 510400, China. 24 Astronomical Institute, St. Petersburg State University, Bibliotechnaya Pl. 2, Petrodvoretz, 198504 St. Petersburg, Russia. 25 Dipartimento di Fisica, Università La Sapienza, Piazzale A.Moro 2, I-00185Rome, Italy. 26 Department of Physics and Astronomy, University ofMissouri-St. Louis, 8001 Natural Bridge Road, St. Louis,MO 63121. 27 Jet Propulsion Laboratory, California Institute of Technology, 4800 OakGroveDrive, Pasadena, CA 91109. 28 Department of Astronomy, Faculty of Science, KyotoUniversity, Kyoto, Japan. 29 Clarke and Coyote Astrophysical Observatory, P.O. Box 930,Wilton, CA 95693. 30 Instituto de Astronomı́a, UNAM,Apartado Postal 70-264, 04510MexicoDF,Mexico. 31 Nyrölä Observatory, Jyväskylän Sirius ry, Kyllikinkatu 1, 40950 Jyväskylä, Finland. 32 GuadarramaObservatory, C/ San Pablo 5, Villalba 28409,Madrid, Spain. 33 Department of Physics, University of Colorado, P.O. Box 173364, Denver, CO 80217-3364. The Astrophysical Journal, 596:847–859, 2003 October 20 # 2003. The American Astronomical Society. All rights reserved. Printed in U.S.A. E

Survey of period variations of superhumps in SU UMa-type dwarf novae. VI. The sixth year (2013-2014)

Continuing the project undertaken by Kato et al. (2009), we collected times of superhump maxima for 56 SU UMa-type dwarf novae mainly observed during the 2013-2014 season and characterized these objects. We detected negative superhumps in VW Hyi and indicated that the low number of normal outbursts in some supercycles can be interpreted as a result of disk tilt. This finding, combined with the Kepler observation of V1504 Cyg and V344 Lyr, suggests that disk tilt is responsible for modulating the outburst pattern in SU UMa-type dwarf novae. We also studied the deeply eclipsing WZ Sge-type dwarf nova MASTER OT J005740.99+443101.5 and found evidence of a sharp eclipse during the phase of early superhumps. The profile can be reproduced by a combination of the eclipse of the axisymmetric disk and the uneclipsed light source of early superhumps. This finding shows the lack of evidence for a greatly enhanced hot spot during the early stage of WZ Sge-type outburst. We detected growing (stage A) superhumps in MN Dra and give a suggestion that some of SU UMa-type dwarf novae situated near the critical condition of tidal instability may show long-lasting stage A superhumps. The large negative period derivatives reported in such systems can be understood as a result of the combination of stage A and B superhumps. Two WZ Sge-type dwarf novae, AL Com and ASASSN-13ck, showed a long-lasting (plateau-type) rebrightening. In the early phase of their rebrightenings, both objects showed a precursor-like outburst, suggesting that the long-lasting rebrightening is triggered by a precursor outburst.

A New SU UMa-Type Dwarf Nova, QW Serpentis (= TmzV46)

We report on the results of the QW Ser campaign, which has been continued from 2000 to 2003 by the VSNET collaboration team. Four long outbursts and many short ones were caught during this period. Our intensive photometric observations revealed superhumps with a period of 0.07700(±0.00004)d during all four superoutbursts, proving the SU UMa nature of this star. The recurrence cycles of the normal outbursts and the superoutbursts were measured to be ∼ 50 days and 240(±30) days, respectively. The change rate of the superhump period was −5.8 ×10 −5 . The distance and the X-ray luminosity in the range of 0.5–2.4keV are estimated to be 380(±60)pc and logLX =3 1.0 ±0.1ergs −1 . These properties have typical values for an SU UMa-type dwarf nova with this

Non-LTE Calculation for the Be Star Decretion Disk

The non-LTE state of the hydrogen gas in isothermal transonic decretion disks around a B1V star has been calculated by an iterative method in order to explore the basic physical process in the disk. This dynamical model is characterized by a density law in the equatorial plane of ρ(R) ∝ R −3.5 . The continuous radiation is calculated with theiteration in the integral form, while we adopt a single-flight escape probability for lines. We describe the non-LTE state, the radiation flow and conversion in the disk. We conclude that the stellar Balmer continuum plays a key role in the non-LTE state of the disk. The examination of the local energy gain and loss suggests that the disk temperature has double minima along the equatorial plane in the optically thick case: the intermediate region caused by deficient ultraviolet radiation and the outer Lyman α cooling region. We have also calculated some observable quantities, such as the spectral energy distribution, the UBV colors, the infrared excess and the Balmer line profiles. Our calculations with the mass loss rate less than 10 −10 M⊙ yr −1 reproduce the observed continuum quantities. However, we could not get large Hα emission strength observed in Be stars. We suggest that the density gradient of the Be star disk is slower than that of the isothermal decretion disk.