- ID:
- ivo://CDS.VizieR/J/ApJ/798/23
- Title:
- Radial velocities of giant stars in NGC 6388
- Short Name:
- J/ApJ/798/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity measurements for 82 stars, members of the Galactic globular cluster (GC) NGC 6388, obtained from ESO-VLT K-band Multi Object Spectrograph (KMOS) spectra acquired during the instrument Science Verification. The accuracy of the wavelength calibration is discussed and a number of tests of the KMOS response are presented. The cluster systemic velocity obtained (81.3+/-1.5km/s) is in very good agreement with previous determinations. While a hint of ordered rotation is found between 9" and 20" from the cluster center, where the distribution of radial velocities is clearly bimodal, more data are needed before drawing any firm conclusions. The acquired sample of radial velocities has also been used to determine the cluster velocity dispersion (VD) profile between ~9" and 70", supplementing previous measurements at r<2" and r>60" obtained with ESO-SINFONI and ESO-FLAMES spectroscopy, respectively. The new portion of the VD profile nicely matches the previous ones, better defining the knee of the distribution. The present work clearly shows the effectiveness of a deployable integral field unit in measuring the radial velocities of individual stars for determining the VD profile of Galactic GCs. It represents the pilot project for an ongoing large program with KMOS and FLAMES at the ESO-VLT, aimed at determining the next generation of VD and rotation profiles for a representative sample of GCs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/526/A112
- Title:
- Radial velocities of HARPS metal-poor sample
- Short Name:
- J/A+A/526/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Searching for extrasolar planets around stars of different metallicity may provide strong constraints to the models of planet formation and evolution. In this paper we present the overall results of a HARPS (a high-precision spectrograph mostly dedicated to deriving precise radial velocities) program to search for planets orbiting a sample of 104 metal-poor stars (selected [Fe/H] below -0.5). Radial velocity time series of each star are presented and searched for signals using several statistical diagnostics. tars with detected signals are presented, including 3 attributed to the presence of previously announced giant planets orbiting the stars HD171028, HD181720, and HD190984. Several binary stars and at least one case of a coherent signal caused by activity-related phenomena are presented. One very promising new, possible giant planet orbiting the star HD107094 is discussed, and the results are analyzed in light of the metallicity-giant planet correlation. We conclude that the frequency of giant planets orbiting metal-poor stars may be higher than previously thought, probably reflecting the higher precision of the HARPS survey. In the metallicity domain of our sample, we also find evidence that the frequency of planets is a steeply rising function of the stellar metal content, as found for higher metallicity stars.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A35
- Title:
- Radial velocities of HD 41248
- Short Name:
- J/A+A/566/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for planets orbiting metal-poor stars is of uttermost importance for our understanding of the planet formation models. However, no dedicated searches have been conducted so far for very low mass planets orbiting such objects. Only a few cases of low mass planets orbiting metal-poor stars are thus known. Amongst these, HD 41248 is a metal-poor, solar-type star on which a resonant pair of super-Earth like planets has been announced. This detection was based on 62 radial velocity measurements obtained with the HARPS spectrograph (public data). In the present paper we present a new planet search program that is using the HARPS spectrograph to search for Neptunes and Super-Earths orbiting a sample of metal-poor FGK dwarfs. We then present a detailed analysis of an additional 162 radial velocity measurements of HD 41248, obtained within this program, with the goal of confirming the existence of the proposed planetary system. We analyzed the precise radial velocities, obtained with the HARPS spectrograph, together with several stellar activity diagnostics and line profile indicators. A careful analysis shows no evidence for the planetary system previously announced. One of the signals, with a period of ~25 days, is shown to be related to the rotational period of the star, and is clearly seen in some of the activity proxies. The remaining signal (P~18 days) could not be convincingly retrieved in the new data set. We discuss possible causes for the complex (evolving) signals observed in the data of HD 41248, proposing that they may be explained by the appearance and disappearance of active regions on the surface of a star with strong differential rotation, or by a combination of the sparse data sampling and active region evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/152/167
- Title:
- Radial velocities of HD 133131A and HD 133131B
- Short Name:
- J/AJ/152/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new precision radial velocity (RV) data set that reveals multiple planets orbiting the stars in the ~360 au, G2+G2 "twin" binary HD133131AB. Our six years of high-resolution echelle observations from MIKE and five years from the Planet Finder Spectrograph (PFS) on the Magellan telescopes indicate the presence of two eccentric planets around HD133131A with minimum masses of 1.43+/-0.03 and 0.63+/-0.15M_J_ at 1.44+/-0.005 and 4.79+/-0.92au, respectively. Additional PFS observations of HD133131B spanning five years indicate the presence of one eccentric planet of minimum mass 2.50+/-0.05M_J_ at 6.40+/-0.59au, making it one of the longest-period planets detected with RV to date. These planets are the first to be reported primarily based on data taken with the PFS on Magellan, demonstrating the instrument's precision and the advantage of long-baseline RV observations. We perform a differential analysis between the Sun and each star, and between the stars themselves, to derive stellar parameters and measure a suite of 21 abundances across a wide range of condensation temperatures. The host stars are old (likely ~9.5Gyr) and metal-poor ([Fe/H]~-0.30), and we detect a ~0.03dex depletion in refractory elements in HD133131A versus B (with standard errors ~0.017). This detection and analysis adds to a small but growing sample of binary "twin" exoplanet host stars with precise abundances measured, and represents the most metal-poor and likely oldest in that sample. Overall, the planets around HD133131A and B fall in an unexpected regime in planet mass-host star metallicity space and will serve as an important benchmark for the study of long-period giant planets.
- ID:
- ivo://CDS.VizieR/J/AJ/154/120
- Title:
- Radial velocities of HD 96511, HR 7578, and KZ And
- Short Name:
- J/AJ/154/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737+/-0.00002, 46.81610+/-0.00006, and 3.0329113+/-0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions (a_1_ sin i and a_2_ sin i) and minimum masses (m_1_ sin^3^i and m_2_ sin^3^i) of the binary components all have accuracies of 0.2% or better. Extensive photometry of the chromospherically active binary HR 7578 confirms a rather long rotation period of 16.446+/-0.002 days and that the K3 V components do not eclipse. We have estimated the basic properties of the stars in the three systems and compared those results with evolutionary tracks. The results for KZ And that we computed with the revised Hipparcos parallax of van Leeuwen (Cat. I/311) produce inconsistencies. That parallax appears to be too large, and so, instead, we used the original Hipparcos parallax of the common proper motion primary, which improves the results, although some problems remain.
- ID:
- ivo://CDS.VizieR/J/AJ/149/63
- Title:
- Radial velocities of HD 54371, HR 2692, and 16 UMa
- Short Name:
- J/AJ/149/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With extensive sets of new radial velocities we have determined orbital elements for three previously known spectroscopic binaries, HD 54371, HR 2692, and 16 UMa. All three systems have had the lines of their secondaries detected for the first time. The orbital periods range from 16.24 to 113.23days, and the three binaries have modestly or moderately eccentric orbits. The secondary to primary mass ratios range from 0.50 to 0.64. 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 binary components all have accuracies of {<=}1%. With our spectroscopic results and the Hipparcos data, we also have determined astrometric orbits for two of the three systems, HR 2692 and 16 UMa. The primaries of HD 54371 and 16 UMa are solar-type stars, and their secondaries are likely K or M dwarfs. The primary of HR 2692 is a late-type subgiant and its secondary is a G or K dwarf. The primaries of both HR 2692 and 16 UMa may be pseudosynchronously rotating, while that of HD 54371 is rotating faster than its pseudosynchronous velocity.
- ID:
- ivo://CDS.VizieR/J/AJ/124/1118
- Title:
- Radial velocities of high-velocity white dwarfs
- Short Name:
- J/AJ/124/1118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocities and complete space motions were measured for 116 white dwarf stars with M dwarf companions (WD+M), including thirteen pairs having "halo-like" velocities. These 116 WD+dM binaries were observed on the 3.5 m telescope at the Apache Point Observatory (APO) on nearly 30 half-nights between 2000 September 4 and 2001 October 20. The APO Double Imaging Spectrograph was used with a 15" slit, yielding a resolution of approximately 2arcsrc/pixel. From the near-solar abundance levels of the M dwarf companions, only one potential stellar halo white dwarf (LP 164-52) was found in the sample, 12 of the 13 high-velocity white dwarfs being actually part of the high-velocity tail of the thick disk rather than the dark matter halo of the Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/L33
- Title:
- Radial velocities of 2 hot Jupiters in Praesepe
- Short Name:
- J/ApJ/756/L33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two giant planets orbiting stars in Praesepe (also known as the Beehive Cluster). These are the first known hot Jupiters in an open cluster and the only planets known to orbit Sun-like, main-sequence stars in a cluster. The planets are detected from Doppler-shifted radial velocities; line bisector spans and activity indices show no correlation with orbital phase, confirming the variations are caused by planetary companions. Pr0201b orbits a V=10.52 late F dwarf with a period of 4.4264+/-0.0070 days and has a minimum mass of 0.540+/-0.039M_Jup_, and Pr0211b orbits a V=12.06 late G dwarf with a period of 2.1451+/-0.0012 days and has a minimum mass of 1.844+/-0.064M_Jup_. The detection of two planets among 53 single members surveyed establishes a lower limit of 3.8^+5.0^_-2.4_% on the hot Jupiter frequency in this metal-rich open cluster. Given the precisely known age of the cluster, this discovery also demonstrates that, in at least two cases, giant planet migration occurred within 600Myr after formation. As we endeavor to learn more about the frequency and formation history of planets, environments with well-determined properties--such as open clusters like Praesepe--may provide essential clues to this end.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A26
- Title:
- Radial velocities of hot subluminous stars
- Short Name:
- J/A+A/577/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims to find sdBs with compact companions such as massive white dwarfs, neutron stars, or black holes. Here we provide classifications, atmospheric parameters, and a complete radial velocity (RV) catalogue containing 1914 single measurements for a sample of 177 hot subluminous stars discovered based on SDSS DR7; 110 stars show significant RV variability, while 67 qualify as candidates. We constrain the fraction of close massive compact companions of hydrogen-rich hot subdwarfs in our sample to be smaller than 1.3%, which is already close to the theoretical predictions. However, the sample might still contain such binaries with longer periods exceeding 8d. We detect a mismatch between the {Delta}RV_max_-distribution of the sdB and the more evolved sdOB and sdO stars, which challenges our understanding of their evolutionary connection. Furthermore, irregular RV variations of unknown origin with amplitudes of up to 180km/s on timescales of years, days, and even hours have been detected in some He-sdO stars. They might be connected to irregular photometric variations in some cases.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/3197
- Title:
- Radial velocities of Hyades members
- Short Name:
- J/MNRAS/477/3197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the membership of the Hyades open cluster, derive kinematically modelled parallaxes of its members, and study the colour-absolute magnitude diagram of the cluster. We use Gaia DR1 Tycho-Gaia Astrometric Solution (TGAS) data complemented by Hipparcos-2 data for bright stars not contained in TGAS. We supplement the astrometric data with radial velocities collected from a dozen literature sources. By assuming that all cluster members move with the mean cluster velocity to within the velocity dispersion, we use the observed and the expected motions of the stars to determine individual cluster membership probabilities. We subsequently derive improved parallaxes through maximum-likelihood kinematic modelling of the cluster. This method has an iterative component to deal with 'outliers', caused for instance by double stars or escaping members. Our method extends an existing method and supports the mixed presence of stars with and without radial velocities. We find 251 candidate members, 200 of which have a literature radial velocity, and 70 of which are new candidate members with TGAS astrometry. The cluster is roughly spherical in its centre but significantly flattened at larger radii. The observed colour-absolute magnitude diagram shows a clear binary sequence. The kinematically modelled parallaxes that we derive are a factor ~1.7/2.9 more precise than the TGAS/ Hipparcos-2 values and allow us to derive an extremely sharp main sequence. This sequence shows evidence for fine-detailed structure that is elegantly explained by the full spectrum turbulence model of convection.