Search Publications
The orbital solution and dynamical masses of the binary system V* PX Virginis
Wang, Xiaoli; Fu, Yanning; Xia, Fang
V* PX Vir is a nearby single-lined spectroscopic binary with the primary being a variable of a BY Dra-type star. It has a period of ~216 d and the components of the system are two low-mass pre-main-sequence stars. By a simultaneous least-squares fit to the radial velocities, the relative positions, and the revised Hipparcos intermediate astrometri…
Annual parallax measurements of a semi-regular variable star SV Pegasus with VERA
Honma, Mareki; Nakagawa, Akiharu; Nagayama, Takahiro +6 more
Many studies have shown that there are clear sequences in the period-luminosity relationship (PLR) for Mira variables and semi-regular variables (SRVs) in the Large Magellanic Cloud (LMC). To investigate the PLR for SRVs in our galaxy, we examined the annual parallax measurement and conducted K'-band photometric monitoring of an SRV star SV Pegasu…
The bright-star masks for the HSC-SSP survey
Oguri, Masamune; Medezinski, Elinor; Bosch, James +4 more
We present the procedure to build and validate the bright-star masks for the Hyper-Suprime-Cam Strategic Subaru Proposal (HSC-SSP) survey. To identify and mask the saturated stars in the full HSC-SSP footprint, we rely on the Gaia and Tycho-2 star catalogues. We first assemble a pure star catalogue down to GGaia < 18 after removing ∼…
Parallax of a Mira variable R Ursae Majoris studied with astrometric VLBI
Kurayama, Tomoharu; Honma, Mareki; Nakagawa, Akiharu +5 more
We have measured an annual parallax of the Mira variable R Ursae Majoris (R UMa) with the VLBI Exploration for Radio Astronomy (VERA). From the monitoring VLBI observations over a span of about two years, we detected H2O maser spots in the LSR velocity range from 37 to 42 km s-1. We derived an annual parallax of 1.97 ± 0.05 m…
Near-infrared spectroscopy of M dwarfs. I. CO molecule as an abundance indicator of carbon†
Tsuji, Takashi; Nakajima, Tadashi
Based on the near-infrared spectra of 42 M dwarfs, carbon abundances are determined from the ro-vibrational lines of the CO (2-0) band. We apply Teff values based on the angular diameters if available or use the Teff values in a log Teff-M3.4 relation (M3.4 is the absolute magnitude at 3.4 &mi…
Observations and Orbital Analysis of the High-Amplitude Delta Scuti Star SZLyncis: The Unusual Orbital Precession
Li, Lin-Jia; Qian, Sheng-Bang
We determined forty-two new times of light maximum from our photometry observations and WASP project, and collected all times of light maximum observed between 1961 and 2013 in order to calculate the orbital elements of the SZ Lyncis system and the secular change of the pulsation period with the classical O - C method. We confirmed the decrease of…
VLBI Astrometry of the Semiregular Variable RX Bootis
Tafoya, Daniel; Kurayama, Tomoharu; Honma, Mareki +10 more
We present distance measurements of the semiregular variable RX Bootis (RX Boo) with its annual parallax. Using the unique dual-beam system of the VLBI Exploration of Radio Astrometry (VERA) telescope, we conducted astrometric observations of a water maser spot accompanying RX Boo, referred to the quasar J1419+2706 separated by 1.°69 from RX Boo. …
Study of Eclipsing Binary and Multiple Systems in OB Associations. I. Orion OB1a - IM Monocerotis
Bilir, Selçuk; Bakis, Volkan; Bakis, Hicran +5 more
All available photometric and spectroscopic observations were collected and used as the basis of a detailed analysis of the close binary IM Mon. The orbital period of the binary was refined to 1d.19024249 (0.00000014). The Roche equipotentials, fractional luminosities (in Β,V, and Hp-bands) and fractional radii for the component stars i…
Radial Velocity Search for Extrasolar Planets in Visual Binary Systems
Sato, Bun'ei; Itoh, Yoichi; Oasa, Yumiko +7 more
We searched for extrasolar planets in visual binary systems using precise Doppler-shift measurements taken over a period of 4 yr. Using the HIgh Dispersion Echelle Spectrograph (HIDES) equipped on the Okayama Astrophysical Observatory (OAO) 188cm reflector, we achieved a radial-velocity precision of about 10ms-1. We monitored both prima…
Search for Remnant Clouds Associated with the TW Hya Association
Tachihara, Kengo; Fukui, Yasuo; Neuhäuser, Ralph
We report on a search for the parental molecular clouds of the TW Hya association (TWA), using CO emission and NaI absorption lines. TWA is the nearest young (∼50pc; ∼10Myr) stellar association; yet in spite of its youth there has been no detection of any associated natal molecular gas, as is the case with other typical young clusters. Using infra…