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5731. RVs and RI-photometry of HATS-37 and HATS-38
ID:
ivo://CDS.VizieR/J/AJ/160/222
Title:
RVs and RI-photometry of HATS-37 and HATS-38
Short Name:
J/AJ/160/222
Date:
09 Mar 2022 22:00:00
Publisher:
CDS
Description:
We report the discovery of two transiting Neptunes by the HATSouth survey. The planet HATS-37Ab has a mass of 0.099{+/-}0.042M_Jup_ (31.5{+/-}13.4M{Earth}) and a radius of 0.606{+/-}0.016R_Jup_, and is on a P=4.3315day orbit around a V=12.266{+/-}0.030mag, 0.843_-0.012_^+0.017^M{odot} star with a radius of 0.877_-0.012_^+0.019^R{odot}. We also present evidence that the star HATS-37A has an unresolved stellar companion HATS-37B, with a photometrically estimated mass of 0.654{+/-}0.033M{odot}. The planet HATS-38b has a mass of 0.074{+/-}0.011M_Jup_ (23.5{+/-}3.5M{Earth}) and a radius of 0.614{+/-}0.017R_Jup_, and is on a P=4.3750day orbit around a V=12.411{+/-}0.030mag, 0.890_-0.012_^+0.016^M{odot} star with a radius of 1.105{+/-}0.016 R{odot}. Both systems appear to be old, with isochrone-based ages of 11.46_-1.45_^+0.79^Gyr, and 11.89{+/-}0.60Gyr, respectively. Both HATS-37Ab and HATS-38b lie in the Neptune desert and are thus examples of a population with a low occurrence rate. They are also among the lowest-mass planets found from ground-based wide-field surveys to date.
5732. RVs & V-band LCs of probable members of Cyg OB2
ID:
ivo://CDS.VizieR/J/ApJ/811/85
Title:
RVs & V-band LCs of probable members of Cyg OB2
Short Name:
J/ApJ/811/85
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the "Cygnus X" complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this l~=80{deg} sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg OB2. We find distances of 1.33+/-0.17, 1.32+/-0.07, 1.44+/-0.18, and 1.32+/-0.13kpc toward MT91 372, MT91 696, CPR2002 A36, and Schulte 3, respectively. We adopt a weighted average distance of 1.33+/-0.06kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg OB2. We also identify Schulte 3C (O9.5V), a 4" visual companion to the 4.75 day binary Schulte 3(A+B), as a previously unrecognized Association member.
5733. RV variability in SDSS dwarf carbon stars
ID:
ivo://CDS.VizieR/J/ApJ/877/44
Title:
RV variability in SDSS dwarf carbon stars
Short Name:
J/ApJ/877/44
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dwarf carbon (dC) stars (main-sequence stars showing carbon molecular bands) were initially thought to be an oxymoron because only asymptotic giant branch (AGB) stars dredge carbon into their atmospheres. Mass transfer from a former AGB companion that has since faded to a white dwarf seems the most likely explanation. Indeed, a few types of giants known to show anomalous abundances- notably, the CH, Ba and CEMP-s stars-are known to have a high binary frequency. The dC stars may be the enhanced-abundance progenitors of most, if not all of these systems, but this requires demonstrating a high binary frequency for dCs. Here, for a sample of 240 dC stars targeted for repeat spectroscopy by the SDSS-IV's Time Domain Spectroscopic Survey, we analyze radial velocity (RV) variability to constrain the binary frequency and orbital properties. A handful of dC systems show large velocity variability (>100km/s). We compare the dCs to a control sample with a similar distribution of magnitude, color, proper motion, and parallax. Using Markov chain Monte Carlo methods, we use the measured {Delta}RV distribution to estimate the binary fraction and the separation distribution assuming both a unimodal and bimodal distribution. We find the dC stars have an enhanced binary fraction of 95%, consistent with them being products of mass transfer. These models result in mean separations of less than 1 au corresponding to periods on the order of 1 yr. Our results support the conclusion that dC stars form from close binary systems via mass transfer.
5734. RXJ1604.3-2130A griz and JHK light curves
ID:
ivo://CDS.VizieR/J/A+A/633/A37
Title:
RXJ1604.3-2130A griz and JHK light curves
Short Name:
J/A+A/633/A37
Date:
21 Oct 2021
Publisher:
CDS
Description:
RX J1604.3-2130A is a young, dipper-type, variable star in the Upper Scorpius association, suspected to have an inclined inner disk with respect to its face-on outer disk. We study the eclipses to constrain the inner disk properties. We use time-resolved photometry from the Rapid Eye Mount telescope and Kepler 2 data to study the multi-wavelength variability, and archival optical and IR data to track accretion, rotation, and changes in disk structure. The observations reveal details of the structure and matter transport through the inner disk. The eclipses show 5d quasi-periodicity, with the phase drifting in time and some periods showing increased/decreased eclipse depth and frequency. Dips are consistent with extinction by slightly processed dust grains in an inclined, irregularly-shaped inner disk locked to the star through two relatively stable accretion structures. The grains are located near the dust sublimation radius (~0.09au) at the corotation radius, and can explain the shadows observed in the outer disk. The total mass (gas and dust) required to produce the eclipses and shadows is a few % of a Ceres mass. Such amount of mass is accreted/replenished by accretion in days to weeks, which explains the variability from period to period. Spitzer and WISE variability reveal variations in the dust content in the innermost disk on a few years timescale, which is consistent with small imbalances (compared to the stellar accretion rate) in the matter transport from the outer to the inner disk. A decrease in the accretion rate is observed at the times of less eclipsing variability and low mid-IR fluxes, confirming this picture. The vsini=16km/s confirms that the star cannot be aligned with the outer disk, but is likely close to equator-on and to be aligned with the inner disk. This anomalous orientation is a challenge for standard theories of protoplanetary disk formation.
5735. RX J105453.3+552102 cluster SDSS photometry
ID:
ivo://CDS.VizieR/J/A+A/527/A143
Title:
RX J105453.3+552102 cluster SDSS photometry
Short Name:
J/A+A/527/A143
Date:
21 Oct 2021
Publisher:
CDS
Description:
The most accepted scenario for the origin of fossil groups is that they are galaxy associations in which the merging rate was fast and efficient. These systems have assembled half of their mass at early epoch of the Universe, subsequently growing by minor mergers, and therefore could contain a fossil record of the galaxy structure formation. We have started an observational project in order to characterize a large sample of fossil groups. In this paper we present the analysis of the fossil system RX J105453.3+552102.
5736. RX J2117.1+3412 (V2027 Cyg) light curves
ID:
ivo://CDS.VizieR/J/A+A/558/A63
Title:
RX J2117.1+3412 (V2027 Cyg) light curves
Short Name:
J/A+A/558/A63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the effort to search for white dwarf p-mode oscillations in RX J2117.1+3412 (V2027 Cyg), a GW Vir star. The data were taken with Miosotys, a multi-fiber photometer, mounted on the 1.93-m telescope at Observatoire de Haute-Provence (OHP) with a 20-Hz cadence in May 2010 and June 2012. Two intriguing signatures at 1.2081Hz and 2.5852Hz were found at 3.8{sigma} and 3.5{sigma} significance levels, respectively. However, possible atmospheric effects cannot be ruled out. If these two features are not real, the 3{sigma} upper limit of the relative amplitude for the possible oscillations in the frequency range from 1 to 10Hz is estimated to be about 6x10^-4^. This is the first report in the literature for a p-mode oscillation search of GW Vir stars.
5737. 1RXS J073346.0+261933 light curve
ID:
ivo://CDS.VizieR/J/PAZh/37/924
Title:
1RXS J073346.0+261933 light curve
Short Name:
J/PAZh/37/924
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the course of our search for the optical identifications of ROSAT X-ray sources, we have found a highly variable object with a very unusual behavior on long time scales, rare color indices, and a high X-ray-to-optical flux ratio. We present the archival light curve from the Catalina Sky Survey, optical spectroscopy from RTT150, and time-resolved photometry from the Astrotel-Caucasus telescope. The object appears to be a magnetic cataclysmic variable (a polar) with an orbital period P=3.20h.
5738. RY Sct UBVR photometry
ID:
ivo://CDS.VizieR/J/A+A/374/638
Title:
RY Sct UBVR photometry
Short Name:
J/A+A/374/638
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present study deals with the problem of the estimation of the orbital and physical parameters for the EB-type eclipsing binary RY Sct, based on the interpretation of new photometric U B V R observations. The light curves obtained at the Maidanak Observatory during 1979-94 show a slight asymmetry around the secondary minima and a small difference in the height of the successive maxima. The light curves are analysed in the framework of the Roche computer model (Djurasevic, 1992Ap&SS.196..241D) by applying the inverse-problem method (Djurasevic, 1992Ap&SS.197...17D) based on Marquardt's (1963, J. Soc. Ind. Appl. Math. 11(2), 431) algorithm. The analysis shows that RY Sct system is in an overcontact configuration (f_over_~33%) with q=m_2_/m_1_=m_cool_/m_hot_=3.3 and i~84.3{deg}, generating total-annular eclipses. The basic parameters of the system and of the active region are estimated for all individual U, B, V and R light curves. Our results suggested a mass exchange between the components and mass loss through the outer Lagrangian point L_3_. This could be taken as a possible mechanism in the formation of the circumstellar envelope of toroidal form lying in the orbital plane of the system.
5739. RY Tau in 1996
ID:
ivo://CDS.VizieR/J/A+A/341/553
Title:
RY Tau in 1996
Short Name:
J/A+A/341/553
Date:
21 Oct 2021
Publisher:
CDS
Description:
The T Tauri star RY Tau has increased its brightness from V=10.6mag to V=9.6mag in October-November 1996. By February-March 1997, the star has faded again to V=10.8mag. High-resolution echelle spectra of RY Tau were obtained wit h the SOFIN spectrograph at the Nordic Optical Telescope (La Palma, Spain) at lo w and high brightness levels of the star. No significant changes in the photosph eric lines, which are sensitive to temperature and gravity, were noticed. The spectral type of RY Tau is defined as G1-2IV, which in combination with photomet ric data implies A_V_=1.0-1.3mag. Polarimetric patrol of RY Tau during the fadin g of the star showed an increase of its intrinsic polarization from 0.5-1.0% at high brightness to about 2% at low brightness in the V, R and I bands. The flux radiated in H{alpha} and the IR Ca II emission lines remained about the same, in spite of the one magnitude difference in the continuum flux. These results indicate that variable obscuration of the star by circumstellar dust clo uds was responsible for the brightness change of RY Tau, and that the emission l ine source is mostly outside of the obscured region.
5740. RZ Cas JK light curves
ID:
ivo://CDS.VizieR/J/AJ/116/1447
Title:
RZ Cas JK light curves
Short Name:
J/AJ/116/1447
Date:
21 Oct 2021
Publisher:
CDS
Description:
Light curves of the Algol-type binary system, RZ Cassiopeiae, in the near-IR wavelengths J and K are obtained for the first time. The light curves are analyzed using the Wilson-Devinney model. UBV light curves of RZ Cas obtained by Chambliss are also reanalyzed using the same program. In the J and K bands, the bolometric albedo of the secondary of RZ Cas exhibited values above 0.7, whereas the theoretically expected value for such a star is 0.5. Also, the values of the secondary temperature derived from the J and K light curves are found to be less than that derived from our analysis of the optical light curves as well as from the previous studies in the optical photometric bands. We have attempted to model these effects with a dark spot on the secondary of RZ Cas. The J-band light curve gave a better fit with a cool dark spot on the secondary. Another possible reason for the above mentioned effects is a gas stream from the lobe-filling secondary to the primary star. The magnitudes and colors of the individual components are derived from the observed light curves and the light contributions from the stars derived from the light curve analysis. The primary is found to be an A3 V star as observed by previous investigators. The secondary is classified as K0K4 IV from the derived colors. Seven epochs of primary minima and 3 epochs of secondary minima are obtained from the observations. Because of the increased depths of the secondary eclipse in the infrared bands, the moments of minima are calculated with nearly the same accuracy as that of the primary minima. All the secondary minima are found to occur at phase 0.5. None of the observed primary minima are flat as found by many observers before at optical wavelengths. The colors of the system at the minima obtained by us confirm that the system is partially eclipsing.