- ID:
- ivo://CDS.VizieR/J/other/CoSka/38.538
- Title:
- Radial velocities of TX UMa
- Short Name:
- J/other/CoSka/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-dispersion spectrograms of the interacting close binary TX UMa taken in 1969-73 around the primary minima were used to display the rotational effect of the mass gaining component. The resulting rotational velocity of the gainer is 70.8+/-2.9km/s. The magnitude of the effect points to considerable over-synchronous rotation of the gainer due to direct impact of the gas flow from the loser component onto the surface of the gainer. Some aspects of the secular decrease of the orbital period of the system relevant to this finding are discussed, too.
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- ID:
- ivo://CDS.VizieR/J/A+A/645/A72
- Title:
- Radial velocities of UCAC4 721-037069
- Short Name:
- J/A+A/645/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large radial velocity variations in the LAMOST spectra of giant stars have been used to infer the presence of unseen companions. Some of them have been proposed as possible black hole candidates. We test this selection by investigating the classification of the one candidate that has a known X-ray counterpart (UCAC4 721-037069). We obtained time-resolved spectra from the Liverpool Telescope and a 5 ks observation from the Chandra observatory to fully constrain the orbital parameters and the X-ray emission of this system. We find the source to be an eclipsing stellar binary that can be classified as an RS CVn. The giant star fills its Roche lobe, and the binary mass ratio is greater than one. The system may be an example of stable mass transfer from an intermediate-mass star with a convective envelope Using only radial velocity to identify black hole candidates can lead to many false positives. The presence of an optical orbital modulation, such as what has been observed for all LAMOST candidates, will in most cases indicate that the system is a stellar binary.
- ID:
- ivo://CDS.VizieR/J/AJ/155/255
- Title:
- Radial velocity and activity measurements of HAT-P-11
- Short Name:
- J/AJ/155/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HAT-P-11 is a mid-K dwarf that hosts one of the first Neptune-sized planets found outside the solar system. The orbit of HAT-P-11b is misaligned with the star's spin-one of the few known cases of a misaligned planet orbiting a star less massive than the Sun. We find an additional planet in the system based on a decade of precision radial velocity (RV) measurements from Keck/High Resolution Echelle Spectrometer. HAT-P-11c is similar to Jupiter in its mass (M_P_sin i=1.6+/-0.1 M_J_) and orbital period (P=9.3_-0.5_^+1.0^ year), but has a much more eccentric orbit (e=0.60+/-0.03). In our joint modeling of RV and stellar activity, we found an activity-induced RV signal of ~7 m/s, consistent with other active K dwarfs, but significantly smaller than the 31 m/s reflex motion due to HAT-P-11c. We investigated the dynamical coupling between HAT-P-11b and c as a possible explanation for HAT-P-11b's misaligned orbit, finding that planet-planet Kozai interactions cannot tilt planet b's orbit due to general relativistic precession; however, nodal precession operating on million year timescales is a viable mechanism to explain HAT-P-11b's high obliquity. This leaves open the question of why HAT-P-11c may have such a tilted orbit. At a distance of 38 pc, the HAT-P-11 system offers rich opportunities for further exoplanet characterization through astrometry and direct imaging.
- ID:
- ivo://CDS.VizieR/J/AJ/148/114
- Title:
- Radial velocity curve of {delta} Cir
- Short Name:
- J/AJ/148/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Delta Cir is known as an O7.5 III eclipsing and spectroscopic binary with an eccentric orbit. Penny et al. discovered the presence of a third component in the IUE spectra. The eclipsing binary and the third body revolve around a common center of gravity with a period of 1644days in an eccentric orbit with a semimajor axis of 10AU. We demonstrate the presence of apsidal-line rotation with a period of {approx}141yr, which is considerably longer than its theoretically predicted value, based on the published radii of the binary components derived from the Hipparchos H_p_ light curve. However, our new solution of the same light curve resulted in smaller radii and better agreement between the observed and predicted period of the apsidal-line advance. There are indications that the third body is a binary. The object was resolved by VLTI using the PIONIER combiner; in 2012 June, the separation was 3.78mas with magnitude difference in the H region 1.75fm. This result means that (assuming a distance of 770pc) the inclination of the long orbit is 87.7{deg}.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1137
- Title:
- Radial velocity curve of the HD170582 donor
- Short Name:
- J/MNRAS/448/1137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic and photometric study of the double period variable HD 170582. Based on the study of the ASAS V-band light curve, we determine an improved orbital period of 16.87177+/-0.02084 d and a long period of 587 d. We disentangled the light curve into an orbital part, determining ephemerides and revealing orbital ellipsoidal variability with unequal maxima, and a long cycle, showing quasi-sinusoidal changes with amplitude {Delta}V=0.1mag. Assuming synchronous rotation for the cool stellar component and semidetached configuration we find a cool evolved star of M_2_=1.9+/-0.1 M_{sun}_, T_2_=8000+/-100 K and R_2_=15.6+/-0.2 R_{sun}_, and an early B-type dwarf of M_1_=9.0+/-0.2 M_{sun}_. The B-type star is surrounded by a geometrically and optically thick accretion disc of radial extension 20.8+/-0.3 R_{sun}_ contributing about 35 percent to the system luminosity at the V band. Two extended regions located at opposite sides of the disc rim, and hotter than the disc by 67 and 46 percent, fit the light-curve asymmetries. The system is seen under inclination 67.4{deg}+/-0.4{deg} and it is found at a distance of 238+/-10 pc. Specially interesting is the double line nature of HeI 5875; two absorption components move in antiphase during the orbital cycle; they can be associated with the shock regions revealed by the photometry. The radial velocity of one of the HeI 5875 components closely follows the donor radial velocity, suggesting that the line is formed in a wind emerging near the stream-disc interacting region.
- ID:
- ivo://CDS.VizieR/J/A+A/481/183
- Title:
- Radial velocity curves of V1007 Sco
- Short Name:
- J/A+A/481/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Having obtained new series of electronic spectra and UBV photometry of V1007 Sco, we analysed these data in an effort to check whether the observed properties of V1007 Sco indeed disagree with the prediction of stellar evolutionary models. We briefly analysed data for a few other binaries in NGC 6231, too. Spectral reductions were carried out with the MIDAS program, photometry reduced using the HEC22 program, the orbital elements were derived with the FOTEL program and the final solutions obtained with the program PHOEBE.
- ID:
- ivo://CDS.VizieR/J/ApJ/860/1
- Title:
- Radial velocity measurements of 20 EBs in LMC
- Short Name:
- J/ApJ/860/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a determination of the precise fundamental physical parameters of 20 detached, double-lined, eclipsing binary stars in the Large Magellanic Cloud (LMC) containing G- or early K-type giant stars. Eleven are new systems; the remaining nine are systems already analyzed by our team for which we present updated parameters. The catalog results from our long-term survey of eclipsing binaries in the Magellanic Clouds suitable for high-precision determination of distances (the Araucaria Project). The V-band brightnesses of the systems range from 15.4 to 17.7mag, and their orbital periods range from 49 to 773days. Six systems have favorable geometry showing total eclipses. The absolute dimensions of all eclipsing binary components are calculated with a precision of better than 3%, and all systems are suitable for a precise distance determination. The measured stellar masses are in the range 1.4 to 4.6M_{sun}_, and comparison with the MESA isochrones gives ages between 0.1 and 2.1Gyr. The systems show an age-metallicity relation with no evolution of metallicity for systems older than 0.6Gyr, followed by a rise to a metallicity maximum at age 0.5Gyr and then a slow metallicity decrease until 0.1Gyr. Two systems have components with very different masses: OGLE LMC-ECL-05430 and OGLE LMC-ECL-18365. Neither system can be fitted by a single stellar evolution isochrone, explained by a past mass transfer scenario in the case of ECL-18365 and a gravitational capture or hierarchical binary merger scenario in the case of ECL-05430. The longest-period system, OGLE LMC SC9_230659, shows a surprising apsidal motion that shifts the apparent position of the eclipses. This is a clear sign of a physical companion to the system; however, neither investigation of the spectra nor light-curve analysis indicates a third-light contribution larger than 2%-3%. In one spectrum of OGLE LMC-ECL-12669, we noted a peculiar dimming of one of the components by 65% well outside of the eclipses. We interpret this observation as arising from an extremely rare occultation event, as a foreground Galactic object covers only one component of an extragalactic eclipsing binary.
- ID:
- ivo://CDS.VizieR/J/AJ/130/767
- Title:
- Radial velocity studies of close binary stars
- Short Name:
- J/AJ/130/767
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity measurements and sine-curve fits to orbital velocity variations are presented for the ninth set of 10 close binary systems: V395 And, HS Aqr, V449 Aur, FP Boo, SW Lac, KS Peg, IW Per, V592 Per, TU UMi, and FO Vir. The first three are very close, possibly detached, early-type binaries, and all three require further investigation. Particularly interesting is V395 And, whose spectral type is as early as B7/8 for a 0.685 day orbit binary. KS Peg and IW Per are single-line binaries, with the former probably hosting a very low mass star. We have detected a low-mass secondary in an important semidetached system, FO Vir, at q=0.125+/-0.005. The contact binary FP Boo is also a very small mass ratio system, q=0.106+/-0.005. The other contact binaries in this group are V592 Per, TU UMi, and the well-known SW Lac. V592 Per and TU UMi have bright tertiary companions; for these binaries, and for V395 And, we used a novel technique of arranging the broadening functions into a two-dimensional image in phase. The case of TU UMi turned out to be intractable even using this approach, and we have not been able to derive a firm radial velocity orbit for this binary. Three systems of this group were observed spectroscopically before: HS Aqr, SW Lac, and KS Peg.
- ID:
- ivo://CDS.VizieR/J/A+A/367/236
- Title:
- Radial velocity variations of EN Lac
- Short Name:
- J/A+A/367/236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories and of 994 radial velocities (RV hereafter) from photographic spectra, published by several authors, has allowed us to disentangle the RV variations due to orbital motion and due to pulsations of the star. New, accurate orbital elements as well as precise values of the three pulsation periods, already known from the previous studies, were derived. The accuracy of the orbital solution has been substantially improved after the observed RV changes were properly prewhitened for the short-term oscillations. For the first time we present evidence of line profile variations of EN Lac. They correlate well with the short-term RV variations but they alternatively occur with periods corresponding either to the fundamental periods or to the first harmonics of the short-term RV variations.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A110
- Title:
- R-band light curve of MY Cam
- Short Name:
- J/A+A/572/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The early-type binary MY Cam belongs to the young open cluster Alicante 1, embedded in Cam OB3. MY Cam consists of two early-O type main-sequence stars and shows a photometric modulation suggesting an orbital period slightly above one day. We intend to confirm this orbital period and derive orbital and stellar parameters. Timing analysis of a very exhaustive (4607 points) light curve indicates a period of 1.1754514+/-0.0000015d. High-resolution spectra and the cross-correlation technique implemented in the TODCOR program were used to derive radial velocities and obtain the corresponding radial velocity curves for MY Cam. Modelling with the stellar atmosphere code FASTWIND was used to obtain stellar parameters and create templates for cross-correlation. Stellar and orbital parameters were derived using the Wilson-Devinney code, such that a complete solution to the binary system could be described. We determine masses of the primary and secondary stars in MY Cam are 37.7+/-1.6 and 31.6+/-1.4M_{sun}_ , respectively. The corresponding temperatures, derived from the model atmosphere fit, are 42000 and 39000K, with the more massive component being hotter. Both stars are overfilling their Roche lobes, sharing a common envelope. MY Cam contains the most massive dwarf O-type stars found so far in an eclipsing binary. Both components are still on the main sequence, and probably not far from the zero-age main sequence. The system is a likely merger progenitor, owing to its very short period.
