- ID:
- ivo://CDS.VizieR/J/AJ/153/142
- Title:
- Radial velocities of systems hosting sub-Saturns
- Short Name:
- J/AJ/153/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a Keck/HIRES radial velocity campaign to study four sub-Saturn-sized planets, K2-27b, K2-32b, K2-39b, and K2-108b, with the goal of understanding their masses, orbits, and heavy-element enrichment. The planets have similar sizes (R_P_=4.5-5.5R_{Earth}_), but have dissimilar masses (M_P_=16-60M_{Earth}_), implying a diversity in their core and envelope masses. K2-32b is the least massive (M_P_=16.5+/-2.7M_{Earth}_) and orbits in close proximity to two sub-Neptunes near a 3:2:1 period commensurability. K2-27b and K2-39b are significantly more massive at M_P_=30.9+/-4.6M_{Earth}_ and M_P_=39.8+/-4.4M_{Earth}_, respectively, and show no signs of additional planets. K2-108b is the most massive at M_P_=59.4+/-4.4M_{Earth}_, implying a large reservoir of heavy elements of about {simeq}50M__. Sub-Saturns as a population have a large diversity in planet mass at a given size. They exhibit remarkably little correlation between mass and size; sub-Saturns range from {simeq}6-60M_{Earth}_, regardless of size. We find a strong correlation between planet mass and host star metallicity, suggesting that metal-rich disks form more massive planet cores. The most massive sub-Saturns tend to lack detected companions and have moderately eccentric orbits, perhaps as a result of a previous epoch of dynamical instability. Finally, we observe only a weak correlation between the planet envelope fraction and present-day equilibrium temperature, suggesting that photo-evaporation does not play a dominant role in determining the amount of gas sub-Saturns accrete from their protoplanetary disks.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/588/A144
- Title:
- Radial velocities of 15 targets
- Short Name:
- J/A+A/588/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity planet search surveys of nearby solar-type stars have shown a strong scarcity of brown dwarf companions within ~5AU. There is presently no comprehensive explanation for this lack of brown dwarf companions; therefore, increasing the sample of such objects is crucial to understand their formation and evolution. Based on precise radial velocities obtained using the SOPHIE spectrograph at Observatoire de Haute-Provence we characterise the orbital parameters of 15 companions to solar-type stars and constrain their true mass using astrometric data from the Hipparcos space mission. The nine companions not shown to be stellar in nature have minimum masses ranging from ~13 to 70M_Jup , and are well distributed across the planet/brown dwarf mass regime, making them an important contribution to the known population of massive companions around solar-type stars. We characterise six companions as stellar in nature with masses ranging from a minimum mass of 76+/-4M_Jup_ to a mass of 0.35+/-0.03M_{sun}_. The orbital parameters of two previously known substellar candidates are improved.
- ID:
- ivo://CDS.VizieR/J/ApJ/828/47
- Title:
- Radial velocities of the Be star HR 2142
- Short Name:
- J/ApJ/828/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer (IUE) and ground-based H{alpha} observations. We measured radial velocities for the Be star component from these spectra and computed a revised orbit. In order to search for the spectral signature of the hot subdwarf, we cross-correlated the short wavelength end of each IUE spectrum with a model hot star spectrum, and then we used the predicted Doppler shifts of the subdwarf to shift-and-add all the cross-correlation functions to the frame of the subdwarf. This merged function shows the weak signal from the spectral lines of the hot star, and a best fit is obtained with a mass ratio M_2_/M_1_=0.07+/-0.02, companion temperature T_eff_>=43+/-5kK, projected rotational velocity Vsini<30km/s, and a monochromatic flux ratio near 1170{AA} of f_2_/f_1_>0.009+/-0.001. This hot subdwarf creates a one-armed spiral, tidal wake in the disk of the Be star, and we present a circumbinary disk model that can explain the occurrence of shell absorption lines by gas enhancements that occur where gas crossing the gap created by the subdwarf strikes the disk boundaries. The faint companion of HR 2142 may be representative of a significant fraction of Be stars with undetected former mass donor companion stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/69
- Title:
- Radial velocities of the EB M-dwarf YYGem
- Short Name:
- J/ApJ/873/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- YY Gem is a short-period eclipsing binary system containing two nearly identical, rapidly rotating, very active early M dwarfs. This binary represents an important benchmark system for calibrating empirical relations between fundamental properties of low-mass stars and for testing theories of interior structure and evolution of these objects. Both components of YY Gem exhibit inflated radii, which has been attributed to poorly understood magnetic activity effects. Despite a long history of magnetic activity studies of this system, no direct magnetic field measurements have been made for it. Here we present a comprehensive characterization of the surface magnetic field in both components of YY Gem. We reconstructed the global field topologies with the help of a tomographic inversion technique applied to high-resolution spectropolarimetric data. This analysis revealed moderately complex global fields with a typical strength of 200-300G and anti-aligned dipolar components. A complementary Zeeman intensification analysis of the disentangled intensity spectra showed that the total mean field strength reaches 3.2-3.4kG in both components of YY Gem. We used these results together with other recent magnetic field measurements of M dwarfs to investigate the relation between the global and small-scale fields in these stars. We also assessed predictions of competing magnetoconvection interior structure models developed for YY Gem, finding that only one of them anticipated the surface field strength compatible with our observations. Results of our starspot mapping of YY Gem do not support the alternative family of theoretical stellar models, which attempts to explain the radius inflation by postulating a large spot filling factor.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/10
- Title:
- Radial velocities of the F-type EB* V2154 Cygni
- Short Name:
- J/ApJ/850/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic observations of the 2.63day, detached, F-type main-sequence eclipsing binary V2154 Cyg. We use our observations together with existing uvby photometric measurements to derive accurate absolute masses and radii for the stars that are good to better than 1.5%. We obtain masses of M1=1.269+/-0.017M_{sun}_ and M2=0.7542+/-0.0059M_{sun}_, radii of R1=1.477+/-0.012R_{sun}_ and R2=0.7232+/-0.0091R_{sun}_, and effective temperatures of 6770+/-150K and 5020+/-150K for the primary and secondary stars, respectively. Both components appear to have their rotations synchronized with the motion in the circular orbit. A comparison of the properties of the primary with current stellar evolution models gives good agreement for a metallicity of [Fe/H]=-0.17, which is consistent with photometric estimates, and an age of about 2.2Gyr. On the other hand, the K2 secondary is larger than predicted for its mass by about 4%. Similar discrepancies are known to exist for other cool stars, and are generally ascribed to stellar activity. The system is in fact an X-ray source, and we argue that the main site of the activity is the secondary star. Indirect estimates give a strength of about 1kG for the average surface magnetic field on that star. A previously known close visual companion to V2154 Cyg is shown to be physically bound, making the system a hierarchical triple.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A27
- Title:
- Radial velocities of the HgMn star HD 11733
- Short Name:
- J/A+A/553/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals some possible evidence that a very weak differential rotation is operating in HD 11753.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/57
- Title:
- Radial Velocities of the local universe
- Short Name:
- J/A+AS/102/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper is the second one in a series dedicated to the study of the kinematics of the local universe. It gives 361 new optical and radio redshifts measured at ESO, OHP and Nancay Observatories.
- ID:
- ivo://CDS.VizieR/J/AJ/155/133
- Title:
- Radial velocities of the semi-detached Algol W UMi
- Short Name:
- J/AJ/155/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Double-lined eclipsing binaries allow accurate and direct determination of fundamental parameters such as mass and radius for each component, and they provide important constraints on the stellar structure and evolution models. In this study, we aim to determine a unique set of binary parameters for the Algol system W UMi and to examine its evolutionary status. New high-resolution time-series spectroscopic observations were carried out during 14 nights from 2008 April to 2011 March, and a total of 37 spectra were obtained using the Bohyunsan Optical Echelle Spectrograph. We measured the radial velocities (RVs) for both components, and the effective temperature of the primary star was found to be T_eff,1_=9310+/-90K by a comparison of the observed spectra and the Kurucz models. The physical parameters of W UMi were derived by an analysis of our RV data together with the multi-band light curves of Devinney et al. The individual masses, radii, and luminosities of both components are M1=3.68+/-0.10M_{sun}_ and M2=1.47+/-0.04M_{sun}_, R1=3.88+/-0.03R_{sun}_ and R2=3.13+/-0.03R_{sun}_, and L1=102+/-1L_{sun}_ and L2=7.3+/-0.1L_{sun}_, respectively. A comparison of these parameters with theoretical stellar models showed that the primary component lies in the main-sequence band, while the less massive secondary is noticeably evolved. The results indicate that the initially more massive star became the present secondary by losing most of its own mass via mass transfer to the companion (present primary).
- ID:
- ivo://CDS.VizieR/J/ApJ/899/29
- Title:
- Radial velocities of TOI-1728 with HPF
- Short Name:
- J/ApJ/899/29
- Date:
- 14 Mar 2022 09:03:00
- Publisher:
- CDS
- Description:
- We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an old, inactive M0 star with Teff=3980_-32_^+31^K, which hosts a transiting super-Neptune at an orbital period of ~3.49days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of 5.05_-0.17_^+0.16^ R{Earth}, mass 26.78_-5.13_^+5.43^M{Earth}, and eccentricity 0.057_-0.039_^+0.054^. We estimate the stellar properties, and perform a search for He 10830{AA} absorption during the transit of this planet and claim a null detection with an upper limit of 1.1% with 90% confidence. A deeper level of He 10830{AA} absorption has been detected in the planet atmosphere of GJ3470b, a comparable gaseous planet. TOI-1728b is the largest super-Neptune-the intermediate subclass of planets between Neptune and the more massive gas-giant planets-discovered around an M-dwarf. With its relatively large mass and radius, TOI-1728 represents a valuable data point in the M-dwarf exoplanet mass-radius diagram, bridging the gap between the lighter Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. With a low bulk density of 1.14_-0.24_^+0.26^g/cm^3^, and orbiting a bright host star (J~9.6, V~12.4), TOI-1728b is also a promising candidate for transmission spectroscopy both from the ground and from space, which can be used to constrain planet formation and evolutionary models.
- ID:
- ivo://CDS.VizieR/J/AJ/145/139
- Title:
- Radial velocities of TYC 3010-1494-1
- Short Name:
- J/AJ/145/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R{<~}30000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msini~50M_Jup_) to a solar-type primary. At least three properties of this system allow it to masquerade as a single star with a very-low-mass companion: its large eccentricity (e~0.8), its relatively long period (P~238days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega}~189{deg}). As a result of these properties, for ~95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e~0.3). Only during the ~5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of ~15km/s reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.
