- ID:
- ivo://CDS.VizieR/J/A+A/630/A106
- Title:
- Stellar pulsators in the eclipsing binaries
- Short Name:
- J/A+A/630/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries (EBs) are unique targets for measuring precise stellar properties and can be used to constrain stellar evolution models. In particular, it is possible to measure masses and radii of both components of a double-lined spectroscopic EB at the percent level. Since the advent of high-precision photometric space missions (MOST, CoRoT, Kepler, BRITE, TESS), the use of stellar pulsation properties to infer stellar interiors and dynamics constitutes a revolution for studies of low-mass stars. The Kepler mission has led to the discovery of thousands of classical pulsators such as {delta} Scuti and solar-like oscillators (main sequence and evolved), but also almost 3000 EBs with orbital periods shorter than 1100 days. We report the first systematic search for stellar pulsators in the entire Kepler EB catalog. The focus is mainly aimed at discovering {delta} Scuti, {gamma} Doradus, red giant, and tidally excited pulsators. We developed a data inspection tool (DIT) that automatically produces a series of plots from the Kepler light curves that allows us to visually identify whether stellar oscillations are present in a given time series. We applied the DIT to the whole Kepler EB database and identified 303 systems whose light curves display oscillations, including 163 new discoveries. A total of 149 stars are flagged as {delta} Scuti (100 from this paper), 115 as {gamma} Doradus (69 new), 85 as red giants (27 new), and 59 as tidally excited oscillators (29 new). There is some overlap among these groups, as some display several types of oscillations. Despite the likelihood that many of these systems are false positives, for example, when an EB light curve is blended with a pulsator, this catalog gathers a vast sample of systems that are valuable for a better understanding of stellar evolution.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/416/2477
- Title:
- STEREO observations of variable stars
- Short Name:
- J/MNRAS/416/2477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The feasibility of using data from the NASA STEREO mission for variable star and asteroseismology studies has been examined. A data analysis pipeline has been developed that is able to apply selected algorithms to the entire database of nearly a million stars to search for signs of variability. An analysis limited to stars of magnitude 10.5 has been carried out, which has resulted in the extraction of 263 eclipsing binaries (EBs), of which 122 are not recorded as such in the SIMBAD online database. The characteristics of the STEREO observations are shown to be extremely well-suited to variable star studies with the ability to provide continuous phase coverage for extended periods as well as repeated visits that allow both short and long term variability to be observed. This will greatly inform studies of particular stars, such as the pre-cataclysmic variable V471 Tau, as well as entire classes of stars, including many forms of rotational variability. The high-precision photometry has also revealed a potentially substellar companion to a bright (R=7.5mag) nearby star (HD 213597), detected with 5 sigma significance. This would provide a significant contribution to exoplanet research if follow-up observations ascertain the mass to be within the planetary domain. Some particularly unusual EBs from the recovered sample are discussed, including a possible reclassification of a well-known star as an EB rather than a rotational variable (HR 7355) and several particularly eccentric systems, including very long-period EBs.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A70
- Title:
- Study of an eclipsing binary in M31
- Short Name:
- J/A+A/509/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cosmic distance scale largely depends on distance determinations to galaxies of the Local Group. In this sense, the Andromeda galaxy (M31) is a key rung to better constrain the cosmic distance ladder. A project was started in 1999 to firmly establish a direct and accurate distance to M31 using eclipsing binaries (EBs). After the determination of the first direct distance to M31 from EBs, the second direct distance to an EB system is presented: M31V J00443610+4129194. Light and radial velocity curves were obtained and fitted to derive the masses and radii of the components. The acquired spectra were combined and disentangled to determine the temperature of the components. The analysis of the studied EB resulted in a distance determination to M31 of (m-M)0=24.30+/-0.11mag. This result, when combined with the previous distance determination to M31, results in a distance modulus of (m-M)0=24.36+/-0.08mag (744+/-33kpc), fully compatible with other distance determinations to M31. With an error of only project.
- ID:
- ivo://CDS.VizieR/J/AJ/157/111
- Title:
- Study of three early-type contact twin binaries
- Short Name:
- J/AJ/157/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Three eclipsing binaries, CT Tau, GU Mon, and V701 Sco, are early-type contact binaries with infrared excess from circumbinary matter. We present the multi-color photometry for CT Tau and GU Mon, whose spectral types of B1V are identified by the low-precision spectra. Combining these new light curves (LCs) with previously reported LCs and radial velocity curves, we perform a synthesized analysis to estimate/update the stellar absolute parameters of the three systems. Their mass ratios are close to unity (i.e., q~1), which indicates that the binary system comprising of twin components may be undergoing a slow Case A mass transfer. From the period analysis, the light-time orbit in the (O-C) curve may result from the third condense companion around the binary system although no evidence could be provided by the third light l_3_. From the spectral energy distribution for three binaries, the excess infrared (IR) emissions are above the photospheric emissions, which can be seen at the 22.1 {mu}m for CT Tau and GU Mon, and 11.6 {mu}m, 14.5 {mu}m, and 22.1 {mu}m for V701 Sco, respectively. This kind of infrared excess for the early-type star may be attributed to the circumbinary matter by stellar wind.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/23
- Title:
- Subdwarf A stars vs ELM WDs radial velocities
- Short Name:
- J/ApJ/839/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We address the physical nature of subdwarf A-type (sdA) stars and their possible link to extremely low mass (ELM) white dwarfs (WDs). The two classes of objects are confused in low-resolution spectroscopy. However, colors and proper motions indicate that sdA stars are cooler and more luminous, and thus larger in radius, than published ELM WDs. We demonstrate that surface gravities derived from pure hydrogen models suffer a systematic ~1dex error for sdA stars, likely explained by metal line blanketing below 9000K. A detailed study of five eclipsing binaries with radial velocity orbital solutions and infrared excess establishes that these sdA stars are metal-poor ~1.2M_{sun}_ main sequence stars with ~0.8M_{sun}_ companions. While WDs must exist at sdA temperatures, only ~1% of a magnitude-limited sdA sample should be ELM WDs. We conclude that the majority of sdA stars are metal-poor A-F type stars in the halo, and that recently discovered pulsating ELM WD-like stars with no obvious radial velocity variations may be SX Phe variables, not pulsating WDs.
- ID:
- ivo://CDS.VizieR/J/PASJ/69/75
- Title:
- Superhumps in SU UMa-type dwarf novae
- Short Name:
- J/PASJ/69/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuing the project described by Kato et al. (2009PASJ...61S.395K), we collected times of superhump maxima for 127 SU UMa-type dwarf novae observed mainly during the 2016-2017 season and characterized these objects. We provide updated statistics of the relation between the orbital period and the variation of superhumps, the relation between period variations and the rebrightening type in WZ Sge-type objects. We obtained the period minimum of 0.05290(2)d and confirmed the presence of the period gap above the orbital period ~0.09d. We note that four objects (NY Her, 1RXS J161659.5+620014, CRTS J033349.8-282244, and SDSS J153015.04+094946.3) have supercycles shorter than 100d but show infrequent normal outbursts. We consider that these objects are similar to V503 Cyg, whose normal outbursts are likely suppressed by a disk tilt. These four objects are excellent candidates to search for negative superhumps. DDE 48 appears to be a member of ER UMa-type dwarf novae. We identified a new eclipsing SU UMa-type object, MASTER OT J220559.40-341434.9. We observed 21 WZ Sge-type dwarf novae during this interval and report 18 of them in this paper. Among them, ASASSN-16js is a good candidate for a period bouncer. ASASSN-16ia showed a precursor outburst for the first time in a WZ Sge-type superoutburst. ASASSN-16kg, CRTS J000130.5+050624, and SDSS J113551.09+532246.2 are located in the period gap. We have newly obtained 15 orbital periods, including periods from early superhumps.
- ID:
- ivo://CDS.VizieR/J/A+A/528/A90
- Title:
- SuperWASP short period eclipsing binaries
- Short Name:
- J/A+A/528/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present light curves and periods of 53 candidates for short period eclipsing binary stars identified by SuperWASP. These include 48 newly identified objects with periods <2x10^4^s (~0.23d), as well as the shortest period binary known with main sequence components (GSC2314-0530 = 1SWASP J022050.85+332047.6) and four other previously known W UMa stars (although the previously reported periods for two of these four are shown to be incorrect). The period distribution of main sequence contact binaries shows a sharp cut-off at a lower limit of around 0.22d, but until now, very few systems were known close to this limit. These new candidates will therefore be important for understanding the evolution of low mass stars and to allow investigation of the cause of the period cut-off.
- ID:
- ivo://CDS.VizieR/J/MNRAS/488/4905
- Title:
- SuperWASP transit false positive catalog
- Short Name:
- J/MNRAS/488/4905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions from SuperWASP. In the process of validating planets, many false-positive candidates have also been identified. The TESS telescope is set to begin observations of the northern sky in 2019. Similar to the WASP survey, the TESS pixel size is relatively large (13 arcsec for WASP and 21 arcsec for TESS), making it susceptible to many blended signals and false detections caused principally by grazing and blended stellar eclipsing binary systems. In order to reduce duplication of effort on targets, we present a catalogue of 1041 Northern hemisphere SuperWASP targets that have been rejected as planetary transits through follow-up observation.
- ID:
- ivo://CDS.VizieR/J/A+A/376/158
- Title:
- SV Cam BVR light curves
- Short Name:
- J/A+A/376/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New BVR light curves and times of minimum light for the short period RS CVn system SV Cam were analysed to derive the physical parameters of the system and the parameters of the third body orbit. The light curves obtained at the TUEBITAK National Observatory during two nights in 2000 show considerable asymmetry and night-to-night variations. The analysis of the light curves is made using Djurasevic's inverse problem method. The Roche model with spotted areas on the hotter primary component yields a good fit to observations. The extensive series of published photoelectric minima times indicate that the eclipsing pair orbits around the common mass center of the triple system with a period of 41.32yr.
- ID:
- ivo://CDS.VizieR/J/A+A/406/193
- Title:
- SV Cam BVR light curves in Feb. 2001 - March 2002
- Short Name:
- J/A+A/406/193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of new BVR light curves for the active star SV Cam. The Roche model with spotted areas on the hotter primary component fits satisfactorily all filter observations yielding two spots in intermediate latitudes and covering about 1.5% each of the stellar surface. Both are ~1000K cooler than surrounding photosphere. The comparison with an earlier season (January/February 2000) suggests that the spots probably evolved in area longitude and latitude but basic and preferred orientation from previous season is confirmed. The comparison stars were SAO 1045 (standard) and SAO 1030 (check).
