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961. HARPS and X-shooter spectra of Southern M dwarfs
ID:
ivo://CDS.VizieR/J/ApJ/878/134
Title:
HARPS and X-shooter spectra of Southern M dwarfs
Short Name:
J/ApJ/878/134
Date:
25 Oct 2021 00:49:19
Publisher:
CDS
Description:
We present the homogeneous analysis of a sample of Southern early-type M dwarfs in the solar neighborhood (d<60pc). We used the MCAL technique to derive the effective temperature Teff, metallicity [Fe/H], and activity index i_a_(H_alpha_) of 420 M stars using HARPS spectra. The effective temperature Teff, surface gravity logg, metallicity [Fe/H], and projected rotational velocity V_rot_sini of 153 M0-M6 dwarfs were determined by fitting the observed intermediate-resolution spectra from the VIS arm of VLT/X-shooter with a grid of BT-Settl stellar atmosphere models. We estimated the typical uncertainties of the fit with X-shooter spectra by varying region-to-region results by {sigma}T_eff_~50K, {sigma}logg~0.2, and {sigma}[Fe/H]~0.2dex. Photometric verification of Teff for the 295 stars from the HARPS sample and the 61 stars from the X-shooter sample is also provided. We compared our results from different methods to estimate absolute uncertainty in determining the physical properties of M dwarfs.
962. HARPS, HIRES and AAT Radial Velocities of HD 136352
ID:
ivo://CDS.VizieR/J/AJ/160/129
Title:
HARPS, HIRES and AAT Radial Velocities of HD 136352
Short Name:
J/AJ/160/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD136352 (Nu Lupi) is a naked-eye (V=5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD136352 system, revealing radii of 1.482_-0.056_^+0.058^ R{Earth} and 2.608_-0.077_^+0.078^ R{Earth} for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of {rho}_b_=7.8_-1.1_^+1.2^g/cm3 and {rho}_c_=3.50_-0.36_^+0.41^g/cm3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.
963. HARPS M dwarf sample magnetic activity
ID:
ivo://CDS.VizieR/J/A+A/600/A13
Title:
HARPS M dwarf sample magnetic activity
Short Name:
J/A+A/600/A13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Atmospheric magnetic fields in stars with convective envelopes heat stellar chromospheres, and thus increase the observed flux in the CaII H and K doublet. Starting with the historical Mount Wilson monitoring program, these two spectral lines have been widely used to trace stellar magnetic activity, and as a proxy for rotation period (Prot) and consequently for stellar age. Monitoring stellar activity has also become essential in filtering out false-positives due to magnetic activity in extra-solar planet surveys. The CaII emission is traditionally quantified through the R'_HK_-index, which compares the chromospheric flux in the doublet to the overall bolometric flux of the star. Much work has been done to characterize this index for FGK-dwarfs, but M dwarfs - the most numerous stars of the Galaxy - were left out of these analyses and no calibration of their CaII H and K emission to an R'_HK_ exists to date. We set out to characterize the magnetic activity of the low- and very-low-mass stars by providing a calibration of the R'_HK_-index that extends to the realm of M dwarfs, and by evaluating the relationship between R'_HK_ and the rotation period.. We calibrated the bolometric and photospheric factors for M dwarfs to properly transform the S-index (which compares the flux in the CaII H and K lines to a close spectral continuum) into the R'_HK_. We monitored magnetic activity through the CaII H and K emission lines in the HARPS M dwarf sample.
964. HARPS-N radial velocities of WASP-47
ID:
ivo://CDS.VizieR/J/AJ/154/237
Title:
HARPS-N radial velocities of WASP-47
Short Name:
J/AJ/154/237
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present precise radial velocity observations of WASP-47, a star known to host a hot Jupiter, a distant Jovian companion, and, uniquely, two additional transiting planets in short-period orbits: a super-Earth in a ~19 hr orbit, and a Neptune in a ~9 day orbit. We analyze our observations from the HARPS-N spectrograph along with previously published data to measure the most precise planet masses yet for this system. When combined with new stellar parameters and reanalyzed transit photometry, our mass measurements place strong constraints on the compositions of the two small planets. We find that, unlike most other ultra-short-period planets, the inner planet, WASP-47 e, has a mass (6.83+/-0.66 M_{Earth}_) and a radius (1.810+/-0.027 R_{Earth}_) that are inconsistent with an Earth-like composition. Instead, WASP-47 e likely has a volatile-rich envelope surrounding an Earth-like core and mantle. We also perform a dynamical analysis to constrain the orbital inclination of WASP-47 c, the outer Jovian planet. This planet likely orbits close to the plane of the inner three planets, suggesting a quiet dynamical history for the system. Our dynamical constraints also imply that WASP-47 c is much more likely to transit than a geometric calculation would suggest. We calculate a transit probability for WASP-47 c of about 10%, more than an order of magnitude larger than the geometric transit probability of 0.6%.
965. HARPS-N RVs & activity indicators for Kepler-1655
ID:
ivo://CDS.VizieR/J/AJ/155/203
Title:
HARPS-N RVs & activity indicators for Kepler-1655
Short Name:
J/AJ/155/203
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the confirmation of a small, moderately irradiated (F=155+/-7 F_{Earth}_) Neptune with a substantial gas envelope in a P=11.8728787+/-0.0000085 day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213+/-0.082 R_{Earth}_. We acquired 95 high-resolution spectra with Telescopio Nazionale Galileo/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0_-2.8_^+3.1^ M_{Earth}_ via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.
966. HARPS observations of eight galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/489/1255
Title:
HARPS observations of eight galactic Cepheids
Short Name:
J/A+A/489/1255
Date:
21 Oct 2021
Publisher:
CDS
Description:
We show that residual {gamma}-velocities (compared to a axisymmetric rotation model of the milky Way) are an intrinsic property of Cepheids. We observed eight galactic Cepheids with the HARPS spectroscope, focusing specifically on 17 spectral lines. For each spectral line of each star, we computed the {gamma}-velocity (resp. {gamma}-asymmetry) as an average value of the interpolated radial velocity (resp. line asymmetry) curve. For each Cepheid in our sample, a linear relation is found between the {gamma}-velocities of the various spectral lines and their corresponding {gamma}-asymmetries, showing that residual {gamma}-velocities stem from the intrinsic properties of Cepheids. We also provide a physical reference to the stellar {gamma}-velocity: it should be zero when the {gamma}-asymmetry is zero. Following this definition, we provide very precise and physically calibrated estimates of the {gamma}-velocities for all stars of our sample.
967. HARPS observations of nine galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/453/309
Title:
HARPS observations of nine galactic Cepheids
Short Name:
J/A+A/453/309
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy of the Baade-Wesselink method, and in particular of its interferometric version recently applied to several nearby Cepheids. This work aims at establishing a link between the line asymmetry evolution over the Cepheids' pulsation cycles and their projection factor, with the final objective to improve the accuracy of the Baade-Wesselink method for distance determinations. We present HARPS high spectral resolution observations (R=120000) of nine galactic Cepheids: R Tra, S Cru, Y Sgr, beta Dor, zeta Gem, Y Oph, RZ Vel, l Car and RS Pup, having a good period sampling (P=3.39d to P=41.52d). We fit spectral line profiles by an asymmetric bi-Gaussian to derive radial velocity, Full-Width at Half-Maximum in the line (FWHM) and line asymmetry for all stars.
968. HARPS observations of nine galactic Cepheids
ID:
ivo://CDS.VizieR/J/A+A/502/951
Title:
HARPS observations of nine galactic Cepheids
Short Name:
J/A+A/502/951
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed eight galactic Cepheids with the HARPS spectrograph. For each star, we derive an interpolated cross-correlated radial velocity curve using the HARPS pipeline. Pulsating phases and HARPS radial velocity measurements can be found in Table 1. The cross correlation method is widely used to derive the radial velocity curve of Cepheids when the signal to noise ratio of the spectra is low. However, if it is used with an inac curate projection factor, it might introduce some biases in the Baade-Wesselink (BW) methods of determining the distance of Cepheids. In addition, it might affect the average value of the radial velocity curve (or gamma-velocity) important for Galactic structure studies. See the paper for details and results.
969. HARPSpol magnetic massive stars
ID:
ivo://CDS.VizieR/J/A+A/567/A28
Title:
HARPSpol magnetic massive stars
Short Name:
J/A+A/567/A28
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph.
970. HARPS radial velocities of the host star HD15337
ID:
ivo://CDS.VizieR/J/ApJ/876/L24
Title:
HARPS radial velocities of the host star HD15337
Short Name:
J/ApJ/876/L24
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V=9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary nature of the transit signals and derive the masses of the two transiting planets. With an orbital period of 4.8d, a mass of 7.51_-1.01^+1.09^M{Earth}_ and a radius of 1.64+/-0.06R_{Earth}_, HD15337b joins the growing group of short-period super-Earths known to have a rocky terrestrial composition. The sub-Neptune HD15337c has an orbital period of 17.2d, a mass of 8.11_-1.69_^+1.82^M_{Earth}_, and a radius of 2.39+/-0.12R_{Earth}_, suggesting that the planet might be surrounded by a thick atmospheric envelope. The two planets have similar masses and lie on opposite sides of the radius gap, and are thus an excellent testbed for planet formation and evolution theories. Assuming that HD15337c hosts a hydrogen-dominated envelope, we employ a recently developed planet atmospheric evolution algorithm in a Bayesian framework to estimate the history of the high-energy (extreme ultraviolet and X-ray) emission of the host star. We find that at an age of 150Myr, the star possessed on average between 3.7 and 127 times the high-energy luminosity of the current Sun.

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