- ID:
- ivo://CDS.VizieR/J/AJ/160/175
- Title:
- BVRcIc light curve of eclisping binary V1023 Persei
- Short Name:
- J/AJ/160/175
- Date:
- 09 Dec 2021
- Publisher:
- CDS
- Description:
- V1023 Per is a polar spotted, but well-detached dwarf binary, very likely a Pre-WUMa eclipsing binary. It was observed on 11 nights in 2015 October, November, and December at Dark Sky Observatory in North Carolina with the 0.81m reflector of Appalachian State University. The period behavior is complex and may be increasing with a cubic or quadratic ephemeris. Its odd light curves are of high amplitude but have no totality and reach maximum light just before and following the secondary eclipse, indicating that it has polar spots similar to UV Leo. The 28yr orbital period study calls the attention of observers to further monitor this binary to understand the complex nature of the period evolution. Its presently fixed polar spot does indicate that it must have a strong magnetic field and that it is synchronously rotating. The BVRcIc simultaneous 2016 Wilson-Devinney program (W-D) solution gives fillouts of 68% and 75% for the primary and secondary components, respectively. The polar position of the spot, its radius (24{deg}), and T-fact (0.75) indicate that a strong magnetic field is present. The small {Delta}T in the components (~289K) show that the stars are similar in spectral type despite them being well detached. The inclination is high, ~85.19{deg}{+/-}0.04{deg}, but there is not a total eclipse due to the high mass ratio (~0.739{+/-}0.001). Due to the low galactic position (longitude=150.390{deg}, latitude=-1.023{deg}), its reddening is addressed. The primary components temperature is estimated to be 5250{+/-}250K.
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- ID:
- ivo://CDS.VizieR/J/PASP/121/104
- Title:
- BVRI differential photometry of GW Gem
- Short Name:
- J/PASP/121/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New multiband CCD photometry is presented for the eclipsing binary GW Gem; the RI light curves are the first ever compiled. Four new minimum timings have been determined. Our analysis of eclipse timings observed during the past 79 years indicates a continuous period increase at a fractional rate of +(1.2+/-0.1)x10^10^, in excellent agreement with the value +1.1x10^-10^ calculated from the Wilson-Devinney binary code. The new light curves display an inverse O'Connell effect increasing toward longer wavelengths. Hot- and cool-spot models are developed to describe these variations but we prefer a cool spot on the secondary star. Our light-curve synthesis reveals that GW Gem is in a semidetached, but near-contact, configuration. It appears to consist of a near-main-sequence primary star with a spectral type of about A7 and an evolved early K-type secondary star that completely fills its inner Roche lobe. Mass transfer from the secondary to the primary component is responsible for the observed secular period change.
- ID:
- ivo://CDS.VizieR/J/AJ/161/193
- Title:
- BVRI light curve of RR Lyrea V* AX UMa
- Short Name:
- J/AJ/161/193
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- The pulsation periods of RR-Lyrae stars usually vary with time, and they are often used as probes to study the mechanism behind the variation. After the early discovery that the pulsation period of the RR-Lyrae star AXUMa decreased rapidly, in further research, we made multiband photometric observations of this star using the Sino-Thai 70cm telescope and the 60cm telescope at Yunnan Observatories, and collected its light-curve data from several photometry sky surveys. The O-C diagram confirmed that AX UMa has a rapid period decrease with a rate of -7.752{+/-}0.005days/Myr, which indicates that it is the fastest-period decreasing ab-type RR Lyrae star in the Galactic field. Moreover, the O-C residuals contain additional periodic variations. We suppose that the variation with a long period is probably caused by the light-travel time effect as the star orbits in a binary system. The calculation shows that the lower mass limit of the companion is about 1M{sun}. Combined with the full amplitudes and color indexes, we suggested that the companion is probably a hot subdwarf star. We compared the light curves of AXUMa and those of another binary evolution pulsator, OGLE-BLG-RRLYR-02792, and found that the former shows the characteristics of ab-type RR-Lyrae stars, while the latter is more like an extreme long-period c-type RR-Lyrae star. However, the absence of a bump in the light curves implies that the mass loss has occurred in the outer atmosphere of AXUMa. The special features of AXUMa make it worth more attention and further observations.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A78
- Title:
- BVRI light curves and RV curves of 65 UMa
- Short Name:
- J/A+A/542/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of stellar multiple systems provides us with important information about the stellar formation processes and can help us to estimate the multiplicity fraction in the Galaxy. 65 UMa belongs to a rather small group of stellar systems of higher multiplicity, whose inner and outer orbits are well-known. This allows us to study the long-term stability and evolution of the orbits in these systems. We obtained new photometric and spectroscopic data that when combined with interferometric data enables us to analyze the system 65 UMa and determine its basic physical properties.
- ID:
- ivo://CDS.VizieR/J/A+A/419/167
- Title:
- BVRI photometry in metal-poor binaries
- Short Name:
- J/A+A/419/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explored the regions within a radius of 25 arcsec around 473 nearby, low-metallicity G- to M-type stars using (VR)I optical filters and small-aperture telescopes. About 10% of the sample was searched up to angular separations of 90 arcsec. We applied photometric and astrometric techniques to detect true physical companions to the targets. The great majority of the sample stars was drawn from the Carney-Latham surveys; their metallicities range from roughly solar to [Fe/H]=-3.5dex. Our I-band photometric survey detected objects that are between 0 and 5mag fainter (completeness) than the target stars; the maximum dynamical range of our exploration is 9mag.
- ID:
- ivo://CDS.VizieR/J/AJ/161/292
- Title:
- BVRI photometry of pre-W UMA binary V642 Virginis
- Short Name:
- J/AJ/161/292
- Date:
- 16 Mar 2022 00:08:32
- Publisher:
- CDS
- Description:
- V642Vir is a polar spotted, well-detached, UV Leo-type, low-mass, pre-WUMa (T1~4250K, ~K6V) eclipsing binary. It was observed in 2020 April, May, and June at the Dark Sky Observatory in North Carolina, USA with the 0.81m reflector of Appalachian State University. A total of 88 timings were used in our 22-year period study which included 12 Transiting Exoplanet Survey Satellite (TESS) timings. The O-C plots show a low-amplitude oscillation of residuals that points to the existence of an orbiting third body, a dwarf of minimum mass, 0.15M{sun} in an eccentric orbit (e=0.41), with an orbital period of 20.07yr. The odd light curves of V642 Virginis indicate that it has polar spots similar to UV Leo and the recently published V1023Per. Its present large polar spot region indicates that it must have a strong magnetic field and that it is synchronously rotating. The BVR_c_I_c_ simultaneous Wilson-Devinney Program solution gives a detached binary (primary and secondary components are underfilling their respective Roche Lobes, with 76% and 78% fill outs respectively). The cool spot region models near the pole of the primary component (centered at 10{deg} colatitude) and is angled toward the secondary component. Its large radius (68{deg}) and T-fact (T_spot_/T_surface_=0.69) also attest to the conclusion of the strength of the magnetic field. The small {Delta}T in the components (~318K) and mass ratio near unity (0.9542{+/-}0.0005) show that the stars are similar in spectral type (secondary ~K9V). The inclination is high, ~86.87{+/-}0.04{deg}, yet there is no time of constant light due to the two stars essentially equal radii.
- ID:
- ivo://CDS.VizieR/J/AJ/156/264
- Title:
- California-Kepler Survey. VII. Planet radius gap
- Short Name:
- J/AJ/156/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of planet sizes encodes details of planet formation and evolution. We present the most precise planet size distribution to date based on Gaia parallaxes, Kepler photometry, and spectroscopic temperatures from the California-Kepler Survey. Previously, we measured stellar radii to 11% precision using high-resolution spectroscopy; by adding Gaia astrometry, the errors are now 3%. Planet radius measurements are, in turn, improved to 5% precision. With a catalog of ~1000 planets with precise properties, we probed in fine detail the gap in the planet size distribution that separates two classes of small planets, rocky super-Earths and gas-dominated sub-Neptunes. Our previous study and others suggested that the gap may be observationally under-resolved and inherently flat-bottomed, with a band of forbidden planet sizes. Analysis based on our new catalog refutes this; the gap is partially filled in. Two other important factors that sculpt the distribution are a planet's orbital distance and its host-star mass, both of which are related to a planet's X-ray/UV irradiation history. For lower-mass stars, the bimodal planet distribution shifts to smaller sizes, consistent with smaller stars producing smaller planet cores. Details of the size distribution including the extent of the "sub-Neptune desert" and the width and slope of the gap support the view that photoevaporation of low-density atmospheres is the dominant evolutionary determinant of the planet size distribution.
- ID:
- ivo://CDS.VizieR/J/AJ/153/95
- Title:
- Catalog of Suspected Nearby Young Stars
- Short Name:
- J/AJ/153/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new nearby young moving group (NYMG) kinematic membership analysis code, LocAting Constituent mEmbers In Nearby Groups (LACEwING), a new Catalog of Suspected Nearby Young Stars, a new list of bona fide members of moving groups, and a kinematic traceback code. LACEwING is a convergence-style algorithm with carefully vetted membership statistics based on a large numerical simulation of the Solar Neighborhood. Given spatial and kinematic information on stars, LACEwING calculates membership probabilities in 13 NYMGs and three open clusters within 100 pc. In addition to describing the inputs, methods, and products of the code, we provide comparisons of LACEwING to other popular kinematic moving group membership identification codes. As a proof of concept, we use LACEwING to reconsider the membership of 930 stellar systems in the Solar Neighborhood (within 100 pc) that have reported measurable lithium equivalent widths. We quantify the evidence in support of a population of young stars not attached to any NYMGs, which is a possible sign of new as-yet-undiscovered groups or of a field population of young stars.
- ID:
- ivo://CDS.VizieR/J/A+A/475/1125
- Title:
- Characterization of the hot Neptune GJ 436b
- Short Name:
- J/A+A/475/1125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope infrared photometry of a secondary eclipse as well as ground-based photometric and spectroscopic measurements of the hot Neptune GJ 436b.
- ID:
- ivo://CDS.VizieR/J/A+A/430/137
- Title:
- Close visual companions in Scorpius OB2
- Short Name:
- J/A+A/430/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared adaptive optics survey with the aim to detect close companions to Hipparcos members in the three subgroups of the nearby OB association Sco OB2: Upper Scorpius (US), Upper Centaurus Lupus (UCL) and Lower Centaurus Crux (LCC). We have targeted 199 A-type and late B-type stars in the K_S band, and a subset also in the J and H band. We find 151 stellar components other than the target stars. A brightness criterion is used to separate these components into 77 background stars and 74 candidate physical companion stars. Out of these 74 candidate companions, 41 have not been reported before (14 in US; 13 in UCL; 14 in LCC).