- ID:
- ivo://CDS.VizieR/J/ApJ/835/251
- Title:
- Radial velocities and BVIc LCs of the EB* CU Cnc
- Short Name:
- J/ApJ/835/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral features, radial velocities, elemental abundance estimates, other spectral data, and BVI_C_ light curves are reported for the double-M dwarf eclipsing binary CU Cancri-a good target for a radius check versus the Zero Age Main Sequence (ZAMS) due to the low component masses and corresponding very slow evolutionary expansion. The estimate of [Fe/H] is about 0.4, although continuum placement and other difficulties due to line crowding introduce the usual uncertainties for red dwarfs. Detection of the LiI{lambda}6707 line was attempted, with an estimated upper limit of 50m{AA}. Spectral and photometric indicators of stellar activity are described and illustrated. Other objectives were to measure the stellar radii via simultaneous velocity and light-curve solutions of earlier and new data while also improving the ephemeris by filling gaps in timewise coverage with the new velocities and eclipse data from the new light curves. The radii from our solutions agree within about 2% with those from Ribas, being slightly larger than expected for most estimates of the ZAMS. Some aspects of the red dwarf radius anomaly are briefly discussed. Evolution tracks show only very slight age-related expansion for masses near those in CU Cnc. Such expansion could be significant if CU Cnc were similar in age to the Galaxy, but then its Galactic velocity components should be representative of Population II, and they are not.
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- ID:
- ivo://CDS.VizieR/J/AJ/157/192
- Title:
- Radial velocities and transit times for KOI 4
- Short Name:
- J/AJ/157/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of thousands of planetary systems by Kepler has demonstrated that planets are ubiquitous. However, a major challenge has been the confirmation of Kepler planet candidates, many of which still await confirmation. One of the most enigmatic examples is KOI 4.01, Kepler's first discovered planet candidate detection (as KOI 1.01, 2.01, and 3.01 were known prior to launch). Here we present the confirmation and characterization of KOI 4.01 (now Kepler-1658), using a combination of asteroseismology and radial velocities. Kepler-1658 is a massive, evolved subgiant (M_*_=1.45+/-0.06 M_{sun}_, R_*_=2.89+/-0.12 R_{sun}_) hosting a massive (M_p_=5.88+/-0.47 M_J_, R_p_=1.07+/-0.05 R_J_) hot Jupiter that orbits every 3.85 days. Kepler-1658 joins a small population of evolved hosts with short-period (~<100 days) planets and is now the closest known planet in terms of orbital period to an evolved star. Because of its uniqueness and short orbital period, Kepler-1658 is a new benchmark system for testing tidal dissipation and hot Jupiter formation theories. Using all four years of the Kepler data, we constrain the orbital decay rate to be P=<-0.42 s/yr, corresponding to a strong observational limit of Q'_*_>=4.826x10^3^ for the tidal quality factor in evolved stars. With an effective temperature of T_eff_~6200 K, Kepler-1658 sits close to the spin-orbit misalignment boundary at ~6250 K, making it a prime target for follow-up observations to better constrain its obliquity and to provide insight into theories for hot Jupiter formation and migration.
- ID:
- ivo://CDS.VizieR/J/A+A/487/1095
- Title:
- Radial velocities of AD Boo, VZ Hya, WZ Oph
- Short Name:
- J/A+A/487/1095
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate mass, radius, and abundance determinations from binaries provide important information on stellar evolution, fundamental to central fields in modern astrophysics and cosmology. We aim to determine absolute dimensions and abundances for the three F-type main-sequence detached eclipsing binaries AD Boo, VZ Hya, and WZ Oph and to perform a detailed comparison with results from recent stellar evolutionary models. Methods. uvby light curves and uvby{beta} standard photometry were obtained with the Stromgren Automatic Telescope at ESO, La Silla, radial velocity observations at CfA facilities, and supplementary high-resolution spectra with ESO's FEROS spectrograph. State-of-the-art methods were applied for the analyses: the EBOP and Wilson-Devinney binary models, two-dimensional cross-correlation and disentangling, and the VWA abundance analysis tool.
- ID:
- ivo://CDS.VizieR/J/AJ/149/49
- Title:
- Radial velocities of AW UMa
- Short Name:
- J/AJ/149/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopic observations of AW UMa, obtained on three consecutive nights with a median time resolution of 2.1minutes, have been analyzed using the broadening function method in the spectral window of 22.75nm around the 518nm MgI triplet region. Doppler images of the system reveal the presence of vigorous mass motions within the binary system; their presence puts into question the solid-body rotation assumption of the contact binary model. AW UMa appears to be a very tight, semi-detached binary; the mass transfer takes place from the more massive to the less massive component. The primary, a fast-rotating star with Vsini=181.4+/-2.5km/s, is covered with inhomogeneities: very slowly drifting spots and a dense network of ripples more closely participating in its rotation. The spectral lines of the primary show an additional broadening component (called the "pedestal") that originates either in the equatorial regions, which rotate faster than the rest of the star by about 50km/s, or in an external disk-like structure. The secondary component appears to be smaller than predicted by the contact model. The radial velocity field around the secondary is dominated by accretion of matter transferred from (and possibly partly returned to) the primary component. The parameters of the binary are Asini=2.73+/-0.11R_{sun}_ and M_1_sin^3^i=1.29+/-0.15M_{sun}_, M_2_sin^3^i=0.128+/-0.016M_{sun}_. The mass ratio, q_sp_=M_2_/M_1_=0.099+/-0.003, while still the most uncertain among the spectroscopic elements, is substantially different from the previous numerous and mutually consistent photometric investigations which were based on the contact model. It should be studied why photometry and spectroscopy give such discrepant results and whether AW UMa is an unusual object or if only very high-quality spectroscopy can reveal the true nature of W UMa-type binaries.
- ID:
- ivo://CDS.VizieR/J/AJ/132/769
- Title:
- Radial velocities of 10 close binaries
- Short Name:
- J/AJ/132/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial-velocity measurements and sinecurve fits to orbital radial velocity variations are presented for 10 close binary systems: DU Boo, ET Boo, TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi, and AG Vir. With this contribution, the David Dunlap Observatory program has reached the point of 100 published radial velocity orbits. The radial velocities have been determined using an improved fitting technique that uses rotational profiles to approximate individual peaks in broadening functions. Three systems, ET Boo, VW LMi, and TV UMi, are found to be quadruple, while AG Vir appears to be a spectroscopic triple. ET Boo, a member of a close visual binary with P_vis_=113yr, was previously known to be a multiple system, but we show that the second component is actually a close, non-eclipsing binary. The new observations have enabled us to determine the spectroscopic orbits of the companion, non-eclipsing pairs in ET Boo and VW LMi. A particularly interesting case is VW LMi, for which the period of the mutual revolution of the two spectroscopic binaries is only 355-days. While most of the studied eclipsing pairs are contact binaries, ET Boo is composed of two double-lined detached binaries, and HL Dra is a single-lined detached or semidetached system. Five systems of this group have been observed spectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-lined binary), V566 Oph, and AG Vir, but our new data are of much higher quality than in the previous studies.
- ID:
- ivo://CDS.VizieR/J/AJ/136/586
- Title:
- Radial velocities of 10 close binaries
- Short Name:
- J/AJ/136/586
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity (RV) measurements and sine-curve fits to the orbital RV variations are presented for ten close binary systems: EG Cep, V1191 Cyg, V1003 Her, BD+7 3142, V357 Peg, V407 Peg, V1123 Tau, V1128 Tau, HH UMa, and PY Vir.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1977
- Title:
- Radial velocities of 10 close binaries
- Short Name:
- J/AJ/133/1977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity measurements and sine-curve fits to the orbital radial velocity variations are presented for 10 close binary systems: OO Aql, CC Com, V345 Gem, XY Leo, AM Leo, V1010 Oph, V2612 Oph, XX Sex, W UMa, and XY UMa. Most of these binaries have been observed spectroscopically before, but our data are of higher quality and consistency than in the previous studies. While most of the studied eclipsing pairs are contact binaries, V1010 Oph is probably a detached or semidetached double-lined binary, and XY UMa is a detached, chromospherically active system whose broadening functions clearly show well-defined and localized dark spots on the primary component. A particularly interesting case is XY Leo, which is a member of visually unresolved quadruple system composed of a contact binary and a detached, noneclipsing, active binary with an 0.805 day orbital period. V345 Gem and AM Leo are known members of visual binaries. We found faint visual companions at about 2"-3" from XX Sex and XY UMa.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3655
- Title:
- Radial velocities of 8 close binaries
- Short Name:
- J/AJ/137/3655
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity (RV) measurements and sine curve fits to the orbital RV variations are presented for the last eight close binary systems analyzed in the same way as in the previous papers of this series: QX And, DY Cet, MR Del, HI Dra, DD Mon, V868 Mon, ER Ori, and Y Sex. For another seven systems (TT Cet, AA Cet, CW Lyn, V563 Lyr, CW Sge, LV Vir, and MW Vir), phase coverage is insufficient to provide reliable orbits but RVs of individual components were measured. Observations of a few complicated systems observed throughout the David Dunlap Observatory (DDO) close binary program are also presented; among them is an especially interesting multiple system V857 Her which-in addition to the contact binary-very probably contains one or more subdwarf components of much earlier spectral type. All suspected binaries which were found to be most probably pulsating stars are briefly discussed in terms of mean RVs and projected rotation velocities (vsini) as well as spectral-type estimates. In two of them, CU CVn and V752 Mon, the broadening functions show a clear presence of nonradial pulsations. The previously missing spectral types for Paper I are given here in addition to such estimates for most of the program stars of this paper.
- ID:
- ivo://CDS.VizieR/J/AJ/137/3646
- Title:
- Radial velocities of 10 close binaries
- Short Name:
- J/AJ/137/3646
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity (RV) measurements and sine curve fits to the orbital RV variations are presented for 10 close binary systems: TZ Boo, VW Boo, EL Boo, VZ CVn, GK Cep, RW Com, V2610 Oph, V1387 Ori, AU Ser, and FT UMa. Our spectroscopy revealed two quadruple systems, TZ Boo and V2610 Oph, while three stars showing small photometric amplitudes, EL Boo, V1387 Ori, and FT UMa, were found to be triple systems. GK Cep is a close binary with a faint third component. While most of the studied eclipsing systems are contact binaries, VZ CVn and GK Cep are detached or semidetached double-lined binaries, and EL Boo, V1387 Ori, and FT UMa are close binaries of uncertain binary type. The large fraction of triple and quadruple systems found in this sample supports the hypothesis of formation of close binaries in multiple stellar systems; it also demonstrates that low photometric amplitude binaries are a fertile ground for further discoveries of multiple systems.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A109
- Title:
- Radial velocities of 4 eclipsing binaries
- Short Name:
- J/A+A/649/A109
- Date:
- 16 Mar 2022 00:18:30
- Publisher:
- CDS
- Description:
- The surface brightness-colour relation (SBCR) is a basic tool for establishing precise and accurate distances within the Local Group. Detached eclipsing binary stars with accurately determined radii and trigonometric parallaxes allow calibration of the SBCRs with unprecedented accuracy. We analysed four nearby eclipsing binary stars containing late F-type main sequence components: AL Ari, AL Dor, FM Leo, and BN Scl. We determined very precise spectroscopic orbits and combined them with high-precision ground- and space-based photometry. We derived the astrophysical parameters of their components with mean errors of 0.1% for mass and 0.4% for radius. We combined those four systems with another 24 nearby eclipsing binaries with accurately known radii from the literature for which Gaia EDR3 parallaxes are available in order to derive the SBCRs. The resulting SBCRs cover stellar spectral types from B9 V to G7 V. For calibrations, we used Johnson optical B and V , Gaia GBP and G, and 2MASS JHK bands. The most precise relations are calibrated using the infrared K band and allow angular diameters of A-, F-, and G-type dwarf and subgiant stars to be predicted with a precision of 1%
