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- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2303
- Title:
- Radial velocity curves of alpha Lib A
- Short Name:
- J/MNRAS/437/2303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectroscopy of rapidly rotating binary stars occasionally encounters systems where - paradoxically - the primary is effectively hidden in the light of its secondary. Here, we report on a bright textbook example of this kind with the nearby A-type star {alpha} Lib A. Although discovered as a spectroscopic binary already in the year 1904, a radial velocity curve has never been published up to a point where the existence of the secondary became even suspicious. However, in this work, we demonstrate that {alpha} Lib A is indeed a double-lined spectroscopic binary with a rapidly rotating - and hence almost invisible - A-type primary, accompanied and predominated by a more slowly rotating late-A or early F-type secondary in an eccentric P=70.34d orbit. On account of the shallow absorption lines of the primary, uncertainties remain with its semi-amplitude and hence the exact mass ratio. Yet, with a maximal projected separation that should lie in the range 20 to 25mas, follow-up high-angular resolution observations might soon establish {alpha} Lib Aa-Ab as a visual binary, with a measure for the orbital inclination and precisely determined stellar masses.
- ID:
- ivo://CDS.VizieR/J/AJ/149/83
- Title:
- Radial velocity curves of HD 207651
- Short Name:
- J/AJ/149/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From numerous radial velocities obtained at KPNO and Fairborn Observatory, we have determined the orbital elements of the composite spectrum triple system HD 207651. This system consists of a broad-lined A8 V star and an unseen M dwarf companion in a 1.470739days orbit. Variations of the center-of-mass velocity of this short-period system and velocity variations of a narrow-lined F7: V star have an orbital period of 724.1days or 1.98yr and an eccentricity of 0.39. The revised Hipparcos parallax, corresponding to a distance of 255pc, appears to be too small to yield consistent properties. Instead, we adopt a distance of 150pc.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/3706
- Title:
- Radial velocity curves of {nu} Oct
- Short Name:
- J/MNRAS/460/3706
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 1212 radial-velocity (RV) measurements obtained in the years 2009-2013 using an iodine cell for the spectroscopic binary {nu} Octantis (K1 III/IV). This system (a_bin_~2.6au, P~1050d) is conjectured to have a Jovian planet with a semimajor axis half that of the binary host. The extreme geometry only permits long-term stability if the planet is in a retrograde orbit. Whilst the reality of the planet (P~415d) remains uncertain, other scenarios (stellar variability or apsidal motion caused by a yet unobserved third star) continue to appear substantially less credible based on cross-correlation function bisectors, line-depth ratios and many other independent details. If this evidence is validated but the planet is disproved, the claims of other planets using RVs will be seriously challenged. We also describe a significant revision to the previously published RVs and the full set of 1437 RVs now encompasses nearly 13 yr. The sensitive orbital dynamics allow us to constrain the 3D architecture with a broad prior probability distribution on the mutual inclination, which with posterior samples obtained from an N-body Markov chain Monte Carlo is found to be 152.5^+0.7^_-0.6_{deg}. None of these samples are dynamically stable beyond 10^6^yr. However, a grid search around the best-fitting solution finds a region that has many models stable for 10^7^yr, and includes one model within 1{sigma} that is stable for at least 10^8^yr. The planet's exceptional nature demands robust independent verification and makes the theoretical understanding of its formation a worthy challenge.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A160
- Title:
- Radial velocity data of epsilon Cyg
- Short Name:
- J/A+A/647/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Hamilton Echelle Spectrograph at Lick Observatory, we have obtained precise radial velocities of a sample of 373 G- and K-giant stars from 1999 until 2012, leading to the discovery of several single and multiple planetary systems. The radial velocities of the long-period (~53 years) spectroscopic binary epsilon Cyg (HIP 102488) are found to exhibit additional variations with a much shorter period (~291 days). This signature is not perfectly regular, as its period and amplitude seem to change over time. We intend to improve the orbital solution of the epsilon Cyg system, and attempt to identify the cause of the nearly periodic shorter period variations, which might be due to an additional substellar companion. We use precise radial velocity measurements of the K-giant star epsilon Cyg from Lick Observatory, in combination with a large set of RVs collected more recently with the SONG telescope, as well as archival data sets.
- ID:
- ivo://CDS.VizieR/J/A+A/595/A55
- Title:
- Radial velocity data of HD 59686 A
- Short Name:
- J/A+A/595/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For over 12 years, we have carried out a precise radial velocity (RV) survey of a sample of 373 G- and K-giant stars using the Hamilton Echelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/465/257
- Title:
- Radial velocity in multiple systems
- Short Name:
- J/A+A/465/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We want to improve the knowledge of orbits, physical parameters and statistics of nearby multiple systems. Radial velocities were measured with a correlation spectrometer during 2001-2006 to determine or improve spectroscopic orbits of the components of some visual multiple systems. We compile all available observational data and estimate masses and orbital periods in these hierarchical multiple systems. Masses and ages of evolved components are derived by fitting isochrones. Three new spectroscopic orbits of close sub-systems (HD 52452B, 157358Aab, 219877B) are determined and one more orbit (HD 139461) is improved. The composite-spectrum system HD 157358Aab was resolved by speckle-interferometry; its preliminary combined orbit is computed to guide future interferometric observations.
- ID:
- ivo://CDS.VizieR/J/A+A/374/227
- Title:
- Radial velocity in multiple systems
- Short Name:
- J/A+A/374/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New close sub-systems are reported and studied in eight visual multiple systems. Elements of one double-lined and eight single-lined spectroscopic orbits are given. Magnitudes, colors, spectral types, masses of individual components are estimated by combining all available data. The visual secondary component of the young binary HD 27638 is a double-lined pair of G-type dwarfs on a 17-day orbit with an unseen but massive (>1.2M_{sun}_) spectroscopic tertiary on an 8-year orbit. The invisible secondary of HD 28271A is also massive, but it is not seen probably owing to a high luminosity of the primary - an F7 star with fast axial rotation and active chromosphere which evolves off the Main Sequence. Two additional companions are found in the visual triple system HD 179484.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2798
- Title:
- Radial velocity monitoring of PG 1018-047
- Short Name:
- J/MNRAS/421/2798
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 50 per cent of all known hot subdwarf B stars (sdBs) reside in close (short-period) binaries, for which common-envelope ejection is the most likely formation mechanism. However, Han et al. (2002MNRAS.336..449H, 2003MNRAS.341..669H) predict that the majority of sdBs should form through stable mass transfer leading to long-period binaries. Determining orbital periods for these systems is challenging and while the orbital periods of ~100 short-period systems have been measured, there are no periods measured above 30d. As part of a large programme to characterize the orbital periods of sdB binaries and their formation history, we have found that PG 1018-047 has an orbital period of 759.8+/-5.8d, easily making it the longest period ever detected for a sdB binary. Exploiting the Balmer lines of the subdwarf primary and the narrow absorption lines of the companion present in the spectra, we derive the radial velocity amplitudes of both stars, and estimate the mass ratio M_MS_/M_sdB_=1.6+/-0.2. From the combination of visual and infrared photometry, the spectral type of the companion star is determined to be mid-K.
- ID:
- ivo://CDS.VizieR/J/A+A/442/1023
- Title:
- Radial velocity of 17 bright subdwarf B stars
- Short Name:
- J/A+A/442/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity curves for 15 bright subdwarf B binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. In addition, two bright sdB stars are discovered to be radial velocity variable but the period could not yet be determined. The companions for all systems are unseen.
