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- ID:
- ivo://CDS.VizieR/J/MNRAS/449/1380
- Title:
- Optical chromospheric activity of V711 Tau
- Short Name:
- J/MNRAS/449/1380
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present long-term high-resolution spectroscopic observations of the very active RS Canum Venaticorum-type star V711 Tau, obtained during several observing runs from 1998 to 2004, and study its chromospheric activity. Using the spectral subtraction technique, several optical chromospheric activity indicators [including the He I D_3_, Na I D_1_, D_2_, H{alpha} and Ca II infrared triplet (IRT) lines] formed at different atmospheric heights are analysed. Strong chromospheric emission supports earlier results that indicate that V711 Tau is a very active system. Two large optical flares were detected during our observations. The results suggest that the main part of chromospheric emission is attributed to the primary star of the system. The secondary also presents weak emission but is less active. The ratios of EW_8542_/EW_8498_ indicate that CaII IRT emission arises predominantly from plage-like regions. We have found rotational modulation of chromospheric activity in the H{alpha} and CaII IRT lines, which suggests the presence of the chromospheric active longitudes over the surface of V711 Tau. Two active longitudes separated by about 180{deg} were observed to dominate the activity, and the so-called flip-flop phenomenon was seen during our observations. Moreover, the chromospheric activity level shows a long-term variation that gradually increases from a deep minimum near the year 2002. A close spatial connection of photospheric spots and chromospheric active regions in both short and long timescales was found for V711 Tau.
- ID:
- ivo://CDS.VizieR/J/ApJ/877/29
- Title:
- Opt & NIR SMARTS/ANDICAM photometry for DQ Tau
- Short Name:
- J/ApJ/877/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiepoch optical and near-infrared (NIR) photometry and spectroscopy of the spectroscopic binary T Tauri star DQ Tau. The photometric monitoring, obtained using SMARTS ANDICAM, recovers the previously seen correlation between optical flux and the 15.8d binary orbital period, with blue flux peaks occurring close to most observed periastron passages. For the first time, we find an even more consistent correlation between orbital period and NIR brightness and color. The onset of pulse events in the NIR precedes those in the optical by a few days, on average, with the rise usually starting near apastron orbital phase. We further obtained five epochs of spectroscopy using Infrared Telescope Facility (IRTF) SpeX, with a wavelength range of 0.8-5{mu}m, and derived spectra of the infrared excess emission. The shape and strength of the excess varies with time, with cooler and weaker characteristic dust emission (T~1100-1300K) over most of the binary orbit, and stronger/warmer dust emission (T~1600K, indicative of dust sublimation) just before periastron passage. We suggest that our results are broadly consistent with predictions of simulations of disk structure and accretion flows around close binaries, with the varying dust emission possibly tracing the evolution of accretion streams falling inward through a circumbinary disk cavity and feeding the accretion pulses traced by the optical photometry and NIR emission lines. However, our results also show more complicated behavior that is not fully explained by this simple picture, and will require further observations and modeling to fully interpret.
- ID:
- ivo://CDS.VizieR/J/A+A/473/829
- Title:
- Orbital elements of 156 spectroscopic binaries
- Short Name:
- J/A+A/473/829
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a comprehensive, long-term monitoring programme aiming to improve our knowledge of such binary systems. We monitored the radial velocities of 1309 red giants in 187 open clusters with the Coravel spectrometers for 20 years, with a typical accuracy of 0.4km/s per observation. In total, 289 spectroscopic binaries were detected in the sample. We present first orbits for 67 systems and improved elements for another 64 previously published orbits, based on additional observations. For completeness, 25 published orbits are listed as well. The orbits are based on a total of 4039 observations, an average of 26 per system. Orbital periods range from 41.5 to 14722-days (40yrs), eccentricities from 0.00 to 0.81. The remaining systems have too long periods and/or inadequate phase coverage for an orbit determination at this time or too few observations.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A95
- Title:
- Orbital solutions of eight close sdB binaries
- Short Name:
- J/A+A/562/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars (sdBs) with massive compact companions such as white dwarfs, neutron stars, or stellar-mass black holes. In a supplementary programme we obtained time-resolved spectroscopy of known hot subdwarf binary candidates. Here we present orbital solutions of eight close sdB binaries with orbital periods ranging from 0.1 to 10 days, which allow us to derive lower limits on the masses of their companions. Additionally, a dedicated photometric follow-up campaign was conducted to obtain light curves of the reflection-effect binary HS 2043+0615. We are able to constrain the most likely nature of the companions in all cases but one, making use of information derived from photometry and spectroscopy. Four sdBs have white dwarf companions, while another three are orbited by low-mass main sequence stars of spectral type M.
- ID:
- ivo://CDS.VizieR/J/MNRAS/394/1695
- Title:
- Orbits of {beta} Ret and {nu} Oct
- Short Name:
- J/MNRAS/394/1695
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New astrometric-spectroscopic orbital solutions for the single-line K-giant binaries beta Reticuli (P~5.2yr, e=0.3346+/-0.0004) and nu Octantis (P~2.9yr, e=0.2358+/-0.0003) have been derived based on high-precision spectroscopic radial velocities (RVs) and the Hipparcos astrometry.
- ID:
- ivo://CDS.VizieR/J/ApJ/681/562
- Title:
- Orbits of 5 Cet and AX Mon
- Short Name:
- J/ApJ/681/562
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I discuss the effect of physical distortion on the velocities of close binary components and how we may use the resulting distortion of velocity curves to constrain some properties of binary systems, such as inclination and mass ratio. Precise new velocities for 5 Cet convincingly detect these distortions with their theoretically predicted phase dependence. We can even use such distortions of velocity curves to test Lucy's theory of convective gravity darkening. The observed distortions for TT Hya and 5 Cet require the contact components of those systems to be gravity darkened, probably somewhat more than predicted by Lucy's theory, but clearly not as much as expected for a radiative star. These results imply there is no credible evidence for eccentric orbits in binaries with contact components. I also present some speculative analyses of the observed properties of a binary encased in a nonrotating common envelope, if such an object could actually exist, and discuss how the limb darkening of some recently calculated model atmospheres for giant stars may bias my results for velocity-curve distortions, as well as other results from a wide range of analyses of binary stars.
- ID:
- ivo://CDS.VizieR/J/AJ/146/129
- Title:
- Orbits of 4 double-lined spectroscopic binaries
- Short Name:
- J/AJ/146/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Improved orbital elements for four A-star double-lined spectroscopic binaries have been determined with numerous new radial velocities. Three of the four systems, HR 1528, 2 Sge, and 18 Vul, have moderately short orbital periods of 7.05, 7.39, and 9.31 days, respectively, and also have circular or nearly circular orbits. Only HR 6993 with a period of 14.68 days has a significantly eccentric orbit. The close visual companion of 2 Sge has been detected spectroscopically, and its velocity measured. The orbital dimensions (a_1_sini and a_2_sini) and minimum masses (m_1_sin^3^i and m_2_ sin^3^i) of the short-period binary components all have accuracies of 0.5% or better. We determine basic properties of the individual stars and compare them with solar-abundance evolutionary tracks to estimate their masses. Half of the eight components may be synchronously or pseudosynchronously rotating.
- ID:
- ivo://CDS.VizieR/J/AJ/152/11
- Title:
- Orbits of four triple stars
- Short Name:
- J/AJ/152/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Each of the nearby triple systems HIP 7601, 13498, 23824, and 113597 (HD 10800, 18198, 35877, 217379) consist of solar-type dwarfs with comparable masses, where all three components are resolved spectrally, while the outer pairs are resolved both visually and spectrally. These stars are relatively young (between 100 and 600Myr) and chromospherically active (X-ray sources), although they rotate slowly. I determine the spectroscopic orbits of the inner subsystems (periods 19.4, 14.1, 5.6, 20.3days) and the orbits of the outer systems (periods 1.75, 51, 27, 500years, respectively). For HIP 7601 and 13498, the combined spectro-interferometric outer orbits produce direct measurement of the masses of all of the components, allowing for a comparison with stellar models. The 6708{AA} lithium line is present and its strength is measured in each component individually by subtracting the contributions of the other components. The inner and outer orbits of HIP 7601 are nearly circular, likely co-planar, and have a modest period ratio of 1:33. This study contributes to the characterization of hierarchical multiplicity in the solar neighborhood and provides data for testing stellar evolutionary models and chronology.
- ID:
- ivo://CDS.VizieR/J/A+AS/136/373
- Title:
- Orbits of 8 multiples
- Short Name:
- J/A+AS/136/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New close sub-systems are discovered in 8 visual late-type double stars. Elements of spectroscopic orbits (4 double-lined and 4 single-lined) are given for the components of quadruple systems ADS 1134 and 11163, for the components of triple systems ADS 455, 497, 5436, 8236, 10044, and for the primary of the optical pair ADS 9444. Magnitudes, colors, spectral types, masses of individual components are estimated by combining all available data with Hipparcos parallaxes. Among these stellar systems we note a subdwarf triple ADS 497, an old system with subgiant components ADS 10044, and a visual triple ADS 11163 with additional very low mass (possibly substellar) spectroscopic companion in a 4.6 day orbit. The astrometric orbit of ADS 8236B with a semimajor axis of 30 mas and a period of 4.6 yr may be recoverable from Hipparcos data.
