- ID:
- ivo://CDS.VizieR/J/A+A/336/263
- Title:
- Radial velocities of HR 4049
- Short Name:
- J/A+A/336/263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The C I, Na I D, and H{alpha} lines of the post-AGB binary HR 4049 have been studied. Na I D variability results from a photospheric absorption component ([Na/H]=-1.6+/-0.2) which follows the velocity of the primary and a stationary, non-photospheric component. An emission component is attributed to the circumbinary disc, and an absorption component to mass-loss from the system with a velocity of 5.3+/-0.5km/s. The H{alpha} profile varies with the orbital period. The two strong shell type emission peaks are identified as from one single broad emission feature with an absorption centered around -7.5km/s. The intensity variations are largely attributed to a differential amount of reddening towards the H{alpha} emitting region and the stellar continuum. The radial velocities suggest that the H{alpha} emission moves in phase with the primary, but with a slightly lower velocity amplitude. From this we infer that the H{alpha} emission comes from outside the orbit of the primary, but still gravitationally bound to the primary. H{alpha} also shows a weak emission feature at -21.3+/-3.5km/s, which originates from the circumbinary disc and a weak absorption feature at -7.5+/-1.6km/s due to absorption by the circumbinary disc. We propose two competing models that could account for the observed velocity and intensity variations of the H{alpha} profile. Model I: light from the primary reflects on a localized spot near the inner radius of the circumbinary disc which is closest to the primary. Model II: H{alpha} emission originates in the outer layers of the extended atmosphere of the primary due to activity. These activities are locked to the position of the primary in its orbit. We discuss the similarities of variability and shape of the H{alpha} emission of HR 4049 with those of early type T-Tauri stars (e.g SU Aur).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/624/A38
- Title:
- Radial velocities of K2-36
- Short Name:
- J/A+A/624/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-36 is a K dwarf orbited by two small (R_b_=1.43+/-0.08R_{earth}_ and R_c_=3.2+/-0.3R_{earth}_, close-in (a_b_=0.022AU and a_c_=0.054AU) transiting planets discovered by the Kepler/K2 space observatory. They are representatives of two distinct families of small planets (R_p_<4R_{earth}_) recently emerged from the analysis of Kepler data, with likely a different structure, composition and evolutionary pathways. We revise the fundamental stellar parameters and the sizes of the planets, and provide the first measurement of their masses and bulk densities, which we use to infer their structure and composition. We observed K2-36 with the HARPS-N spectrograph over ~3.5-years, collecting 81 useful radial velocity measurements. The star is active, with evidence for increasing levels of magnetic activity during the observing time span. The radial velocity scatter is ~17m/s due to the stellar activity contribution, which is much larger that the semi-amplitudes of the planetary signals. We tested different methods for mitigating the stellar activity contribution to the radial velocity time variations and measuring the planet masses with good precision. We find that K2-36 is likely a ~1Gyr old system, and by treating the stellar activity through a Gaussian process regression, we measured the planet masses m_b_=3.9+/-1.1M_{earth}_ and m_c_=7.8+/-2.3M_{earth}_. The derived planet bulk densities {rho}_b_=7.2^+2.5^_-2.1_g/cm^3^ and {rho}_c_=1.3^+0.7^_-0.5^g/cm^3^ point out that K2-36b has a rocky, Earth-like composition, and K2-36c is a low-density sub-Neptune. Composed of two planets with similar orbital separations but different densities, K2-36 represents an optimal laboratory for testing the role of the atmospheric escape in driving the evolution of close-in, low-mass planets after ~1Gyr from their formation. Due to their similarities, we performed a preliminary comparative analysis between the systems K2-36 and Kepler-36, which we deem worthy of a more detailed investigation.
- ID:
- ivo://CDS.VizieR/J/AJ/157/116
- Title:
- Radial velocities of K2-291 with HIRES & HARPS-N
- Short Name:
- J/AJ/157/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-291 is a solar-type star with a radius of R_*_=0.899+/-0.034 R_{sun}_ and mass of M_*_=0.934+/-0.038 M_{sun}_. From the K2 C13 data, we found one super-Earth planet (R_p_=1.589_-0.072_^+0.095^ R_{Earth}_) transiting this star on a short period orbit (P=2.225177_-6.8e-5_^+6.6e-5^ days). We followed this system up with adaptive-optic imaging and spectroscopy to derive stellar parameters, search for stellar companions, and determine a planet mass. From our 75 radial velocity measurements using High Resolution Echelle Spectrometer on Keck I and High Accuracy Radial velocity Planet Searcher in the northern hemisphere on Telescopio Nazionale Galileo, we constrained the mass of K2-291 b to M_p_=6.49+/-1.16 M_{Earth}_. We found it necessary to model correlated stellar activity radial velocity signals with a Gaussian process (GP) in order to more accurately model the effect of stellar noise on our data; the addition of the GP also improved the precision of this mass measurement. With a bulk density of {rho}=8.84_-2.03_^+2.50^ g/cm^3^, the planet is consistent with an Earth-like rock/iron composition and no substantial gaseous envelope. Such an envelope, if it existed in the past, was likely eroded away by photoevaporation during the first billion years of the star's lifetime.
- ID:
- ivo://CDS.VizieR/J/ApJ/654/625
- Title:
- Radial velocities of 9 long-period objects
- Short Name:
- J/ApJ/654/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The possible existence of additional long-period planetary-mass objects in the extrasolar planetary systems 47 UMa and 14 Her is investigated. We combine all available radial velocity data on these stars, spanning up to 18yr. For the 47 UMa system, we show that while a second planet improves the fit to all available data, there is still substantial ambiguity as to the orbital parameters of the proposed planetary companion 47 UMa c. We also present new observations that clearly support a long-period companion in the 14 Her system. With a period of 6906+/-70 days, 14 Her c may be in a 4:1 resonance with the inner planet. We also present revised orbital solutions for seven previously known planets, incorporating recent additional data obtained with the 2.7m Harlan J. Smith Telescope at McDonald Observatory.
- ID:
- ivo://CDS.VizieR/J/ApJ/800/22
- Title:
- Radial velocities of long-period planets
- Short Name:
- J/ApJ/800/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD24040b and HD183263c are super-Jupiters with circular orbits and periods longer than 8yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative of an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a 1M_Jup_ planet in a 15yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD74156 double-planet system. We also announce the detection of HD145934b, a 2M_Jup_ planet in a 7.5yr orbit around a giant star. Two of our stars, HD187123 and HD217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period greater than 5yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/67
- Title:
- Radial velocities of low-mass white dwarfs
- Short Name:
- J/ApJ/730/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe spectroscopic observations of 21 low-mass (<=0.45M_{sun}_) white dwarfs (WDs) from the Palomar-Green survey obtained over four years. We use both radial velocities and infrared photometry to identify binary systems, and find that the fraction of single, low-mass WDs is <=30%. We discuss the potential formation channels for these single stars including binary mergers of lower-mass objects. However, binary mergers are not likely to explain the observed number of single low-mass WDs. Thus, additional formation channels, such as enhanced mass loss due to winds or interactions with substellar companions, are likely.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A31
- Title:
- Radial velocities of nearby stars
- Short Name:
- J/A+A/626/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed stars with variable radial velocities to determine their spectroscopic orbits. Velocities of 132 targets taken over a time span reaching 30 years are presented. They were measured with the correlation radial velocity spectrometers (1913 velocities) and the new VUES echelle spectrograph (632 velocities), with typical accuracy of 0.5 and 0.2km/s, respectively. We derived spectroscopic orbits of 57 stars (including 53 first-time orbits), mostly nearby dwarfs of spectral types K and M. Their periods range from 2.2 days to 14 years, some of those are Hipparcos astrometric binaries. Comments on individual objects are provided. Many stars belong to hierarchical systems containing three or more components, including 20 new hierarchies resulting from this project. The preliminary orbit of the young star HIP 47110B has a large eccentricity e=0.47 despite short period of 4.4d; it could be still circularizing. Our results enrich the data on nearby stars and contribute toa better definition of the multiplicity statistics.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/46
- Title:
- Radial velocities of 3 Neptune-mass planet hosts
- Short Name:
- J/ApJ/830/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of three modestly irradiated, roughly Neptune-mass planets orbiting three nearby Solar-type stars. HD42618b has a minimum mass of 15.4+/-2.4 M_{Earth}_, a semimajor axis of 0.55au, an equilibrium temperature of 337K, and is the first planet discovered to orbit the solar analogue host star, HD42618. We also discover new planets orbiting the known exoplanet host stars HD164922 and HD143761 ({rho} CrB). The new planet orbiting HD164922 has a minimum mass of 12.9+/-1.6 M_{Earth}_ and orbits interior to the previously known Jovian mass planet orbiting at 2.1au. HD164922c has a semimajor axis of 0.34au and an equilibrium temperature of 418K. HD143761c orbits with a semimajor axis of 0.44au, has a minimum mass of 25+/-2 M_{Earth}_, and is the warmest of the three new planets with an equilibrium temperature of 445K. It orbits exterior to the previously known warm Jupiter in the system. A transit search using space-based CoRoT data and ground-based photometry from the Automated Photometric Telescopes (APTs) at Fairborn Observatory failed to detect any transits, but the precise, high-cadence APT photometry helped to disentangle planetary-reflex motion from stellar activity. These planets were discovered as part of an ongoing radial velocity survey of bright, nearby, chromospherically inactive stars using the Automated Planet Finder (APF) telescope at Lick Observatory. The high-cadence APF data combined with nearly two decades of radial velocity data from Keck Observatory and gives unprecedented sensitivity to both short-period low-mass, and long-period intermediate-mass planets.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A63
- Title:
- Radial velocities of 7 new HARPS planetary systems
- Short Name:
- J/A+A/527/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are conducting a planet search survey with HARPS since seven years. The volume-limited stellar sample includes all F2 to M0 main-sequence stars within 57.5pc, where extrasolar planetary signatures are systematically searched for with the radial-velocity technics. In this paper, we report the discovery of new substellar companions of seven main-sequence stars and one giant star, detected through multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6m telescope, La Silla, Chile.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A22
- Title:
- Radial velocities of 3 new hot Jupiters
- Short Name:
- J/A+A/563/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision radial-velocity measurements of three solar-type stars: HD 13908, HD 159243, and HIP 91258. The observations were made with the SOPHIE spectrograph at the 1.93m telescope of the Observatoire de Haute-Provence (France). They show that these three bright stars host exoplanetary systems composed of at least two companions.
