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41. CARMENES input catalogue of M dwarfs. IV.
ID:
ivo://CDS.VizieR/J/A+A/621/A126
Title:
CARMENES input catalogue of M dwarfs. IV.
Short Name:
J/A+A/621/A126
Date:
21 Oct 2021
Publisher:
CDS
Description:
The main goal of this work is to measure rotation periods of the M-type dwarf stars being observed by the CARMENES exoplanet survey to help distinguish radial-velocity signals produced by magnetic activity from those produced by exoplanets. Rotation periods are also fundamental for a detailed study of the relation between activity and rotation in late-type stars. We look for significant periodic signals in 622 photometric time series of 337 bright, nearby M dwarfs obtained by long-time baseline, automated surveys (MEarth, ASAS, SuperWASP, NSVS, Catalina, ASAS-SN, K2, and HATNet) and, for 20 stars, obtained by us with four 0.2-0.8m telescopes at high geographical latitudes. We present 142 rotation periods (73 new) from 0.12d to 133d and ten long-term activity cycles (six new) from 3.0a to 11.5a. We compare our determinations with those in the existing literature, investigate the distribution of Prot in the CARMENES input catalogue, the amplitude of photometric variability, and their relation to vsini and pEW(H{alpha}), and identify three very active stars with new rotation periods between 0.34d and 23.6d.
42. CARMENES input catalogue of M dwarfs. V.
ID:
ivo://CDS.VizieR/J/A+A/642/A115
Title:
CARMENES input catalogue of M dwarfs. V.
Short Name:
J/A+A/642/A115
Date:
02 Mar 2022 00:04:08
Publisher:
CDS
Description:
The relevance of M dwarfs in the search for potentially habitable Earth-size planets has grown significantly in the last years. In our on-going effort of comprehensively and accurately characterising confirmed and potential planet-hosting M dwarfs, in particular for the CARMENES survey, we have carried out a comprehensive multi-band photometric analysis involving spectral energy distributions, luminosities, absolute magnitudes, colours, and spectral types, from which we have derived basic astrophysical parameters. We have carefully compiled photometry in 20 passbands from the far-ultraviolet to the mi-infrared, and combined it with the latest parallactic distances and close-multiplicity information, mostly from Gaia DR2, of a sample of 2479 K5 V to L8 stars and ultracool dwarfs, including 2210 nearby, bright, M dwarfs. For that, we have made extensive use of Virtual Observatory tools. We have homogeneously computed accurate bolometric luminosities, effective temperatures of 1843 single stars, derived their radii and masses, studied the impact of metallicity, and compared our results with the literature. The over 40 000 individually-inspected magnitudes, together with the basic data and derived parameters of the stars, one by one and averaged by spectral type, have been made public to the astronomical community. In addition, we have reported 40 new close multiple systems and candidates (rho<3.3-arcsec) and 36 overluminous stars that are assigned to young Galactic populations. In the new era of exoplanet searches around M dwarfs via transit (e.g., TESS, PLATO) and radial velocity (e.g., CARMENES, NIRPS+HARPS), this work is of fundamental importance for stellar and, thus, planetary parameter determination.
43. CARMENES M-dwarfs activity indicators
ID:
ivo://CDS.VizieR/J/A+A/623/A44
Title:
CARMENES M-dwarfs activity indicators
Short Name:
J/A+A/623/A44
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs (CARMENES) survey is searching for Earth-like planets orbiting M dwarfs using the radial velocity method. Studying the stellar activity of the target stars is important to avoid false planet detections and to improve our understanding of the atmospheres of late-type stars. In this work we present measurements of activity indicators at visible and near-infrared wavelengths for 331 M dwarfs observed with CARMENES. Our aim is to identify the activity indicators that are most sensitive and easiest to measure, and the correlations among these indicators. We also wish to characterise their variability. Using a spectral subtraction technique, we measured pseudo-equivalent widths of the HeI D3, H-alpha, HeI 10833, and Pa-beta lines, the NaI D doublet, and the CaII infrared triplet, which have a chromospheric component in active M dwarfs. In addition, we measured an index of the strength of two TiO and two VO bands, which are formed in the photosphere. We also searched for periodicities in these activity indicators for all sample stars using generalised Lomb-Scargle periodograms. We find that the most slowly rotating stars of each spectral subtype have the strongest H-alpha absorption. H-alpha is correlated most strongly with HeI D3, whereas NaI D and the CaII infrared triplet are also correlated with H-alpha. HeI 10833 and Pa-beta show no clear correlations with the other indicators. The TiO bands show an activity effect that does not appear in the VO bands. We find that the relative variations of H-alpha and HeI D3 are smaller for stars with higher activity levels, while this anti-correlation is weaker for NaI D and the CaII infrared triplet, and is absent for HeI 10833 and Pa-beta. Periodic variation with the rotation period most commonly appears in the TiO bands, H-alpha, and in the CaII infrared triplet.
44. 324 CARMENES M dwarfs velocities
ID:
ivo://CDS.VizieR/J/A+A/612/A49
Title:
324 CARMENES M dwarfs velocities
Short Name:
J/A+A/612/A49
Date:
21 Oct 2021
Publisher:
CDS
Description:
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520-1710nm at a resolution of at least R>80000, and we measure its RV, H{alpha} emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700-900nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1m/s in very low mass M dwarfs at longer wavelengths likely requires the use of a 10m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3-4m/s.
45. CARMENES time-resolved CaII H&K catalog
ID:
ivo://CDS.VizieR/J/A+A/652/A116
Title:
CARMENES time-resolved CaII H&K catalog
Short Name:
J/A+A/652/A116
Date:
22 Feb 2022
Publisher:
CDS
Description:
Radial-velocity (RV) jitter caused by stellar magnetic activity is an important factor in state-of-the-art exoplanet discovery surveys such as CARMENES. Stellar rotation, along with heterogeneities in the photosphere and chromosphere caused by activity, can result in false-positive planet detections. Hence, it is necessary to determine the stellar rotation period and compare it to any putative planetary RV signature. Long-term measurements of activity indicators such as the chromospheric emission in the CaII H&K lines enable the identification of magnetic activity cycles. In order to determine stellar rotation periods and study the long-term behavior of magnetic activity of the CARMENES guaranteed time observations (GTO) sample, it is advantageous to extract R'HK time series from archival data, since the CARMENES spectrograph does not cover the blue range of the stellar spectrum containing the Ca II H&K lines. We have assembled a catalog of 11634 archival spectra of 186 M dwarfs acquired by seven different instruments covering the CaII H&K regime: ESPADONS, FEROS, HARPS, HIRES, NARVAL, TIGRE, and UVES. The relative chromospheric flux in these lines, R'HK, was directly extracted from the spectra by rectification with PHOENIX synthetic spectra via narrow passbands around the Ca II H&K line cores. The combination of archival spectra from various instruments results in time series for 186 stars from the CARMENES GTO sample. As an example of the use of the catalog, we report the tentative discovery of three previously unknown activity cycles of M dwarfs. We conclude that the method of extracting R'HK with the use of model spectra yields consistent results for different instruments and that the compilation of this catalog will enable the analysis of long-term activity time series for a large number of M dwarfs.
46. Catalog of DMS-type eclipsing binaries
ID:
ivo://CDS.VizieR/V/121
Title:
Catalog of DMS-type eclipsing binaries
Short Name:
V/121
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue contains information about 113 detached main-sequence (DMS) type detached binaries with known photometric and geometric elements.
47. Catalog of gyro-kinematic ages for ~30000 Kepler stars
ID:
ivo://CDS.VizieR/J/AJ/161/189
Title:
Catalog of gyro-kinematic ages for ~30000 Kepler stars
Short Name:
J/AJ/161/189
Date:
09 Mar 2022 22:00:00
Publisher:
CDS
Description:
Estimating stellar ages is important for advancing our understanding of stellar and exoplanet evolution and investigating the history of the Milky Way. However, ages for low-mass stars are hard to infer as they evolve slowly on the main sequence. In addition, empirical dating methods are difficult to calibrate for low-mass stars as they are faint. In this work, we calculate ages for Kepler F, G, and crucially K and M-dwarfs, using their rotation and kinematic properties. We apply the simple assumption that the velocity dispersion of stars increases over time and adopt an age-velocity-dispersion relation (AVR) to estimate average stellar ages for groupings of coeval stars. We calculate the vertical velocity dispersion of stars in bins of absolute magnitude, temperature, rotation period, and Rossby number and then convert velocity dispersion to kinematic age via an AVR. Using this method, we estimate gyro-kinematic ages for 29949 Kepler stars with measured rotation periods. We are able to estimate ages for clusters and asteroseismic stars with an rms of 1.22Gyr and 0.26Gyr respectively. With our Astraea machine-learning algorithm, which predicts rotation periods, we suggest a new selection criterion (a weight of 0.15) to increase the size of the McQuillan et al. catalog of Kepler rotation periods by up to 25%. Using predicted rotation periods, we estimated gyro-kinematic ages for stars without measured rotation periods and found promising results by comparing 12 detailed age-element abundance trends with literature values.
48. Catalog of 2612 M dwarfs from LAMOST
ID:
ivo://CDS.VizieR/J/AJ/150/42
Title:
Catalog of 2612 M dwarfs from LAMOST
Short Name:
J/AJ/150/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
We develop a template-fit method to automatically identify and classify late-type K and M dwarfs in spectra from the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST). A search of the commissioning data, acquired in 2009-2010, yields the identification of 2612 late-K and M dwarfs. The template fit method also provides spectral classification to half a subtype, classifies the stars along the dwarf-subdwarf (dM/sdM/esdM/usdM) metallicity sequence, and provides improved metallicity/gravity information on a finer scale. The automated search and classification is performed using a set of cool star templates assembled from the Sloan Digital Sky Survey spectroscopic database. We show that the stars can be efficiently classified despite shortcomings in the LAMOST commissioning data which include bright sky lines in the red. In particular we find that the absolute and relative strengths of the critical TiO and CaH molecular bands around 7000{AA} are cleanly measured, which provides accurate spectral typing from late-K to mid-M, and makes it possible to estimate metallicity classes in a way that is more efficient and reliable than with the use of spectral indices or spectral-index based parameters such as {zeta}_TiO/CaH_. Most of the cool dwarfs observed by LAMOST are found to be metal-rich dwarfs (dM). However, we identify 52 metal-poor M subdwarfs (sdM), 5 very metal-poor extreme subdwarfs (esdM) and 1 probable ultra metal-poor subdwarf (usdM). We use a calibration of spectral type to absolute magnitude and estimate spectroscopic distances for all the stars; we also recover proper motions from the SUPERBLINK and PPMXL catalogs. Our analysis of the estimated transverse motions suggests a mean velocity and standard deviation for the UVW components of velocity to be: <U>=-9.8km/s, {sigma}_U_=35.6km/s; <V> =-22.8km/s, {sigma}_V_=30.6km/s; <W> =-7.9km/s, {sigma}_W_=28.4km/s. The resulting values are in general agreement with previous reported results, which yields confidence in our spectral classification and spectroscopic distance estimates, and illustrates the potential for using LAMOST spectra of K and M dwarfs for investigating the chemo-kinematics of the local Galactic disk and halo.
49. Catalogue of bright (K<9) M dwarfs
ID:
ivo://CDS.VizieR/J/MNRAS/435/2161
Title:
Catalogue of bright (K<9) M dwarfs
Short Name:
J/MNRAS/435/2161
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K<9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K<9 M dwarfs currently available and is made available here.
50. Cerro Armazones spectroscopy of F dwarfs
ID:
ivo://CDS.VizieR/J/MNRAS/443/2815
Title:
Cerro Armazones spectroscopy of F dwarfs
Short Name:
J/MNRAS/443/2815
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopic survey of a sample of F stars that have not yet been searched for planets. The observations of 187 stars obtained with the Bochum Echelle Spectrographic Observer of the Cerro Armazones Observatory were aimed at nearby (closer than 70pc) main-sequence stars without sufficient archive ([fiber-fed extended range optical spectrograph (FEROS)/high accuracy radial velocity planet search (HARPS)]) spectroscopy. The primary goal of the survey was to select the best candidates for radial-velocity searches of extrasolar planets. The spectra were analysed using the broadening-function technique, the method of choice for rapid rotators later than about A5. The analysis was focused not only at the determination of projected rotational velocity (defining precision of radial-velocity determination), but also at the detection of previously unknown spectroscopic binaries/multiples or stars showing strong line asymmetries. 12 previously unknown spectroscopic binaries/triples were detected. For all observed targets the spectral type was determined. About 140 stars are rotating faster than the resolution limit of 10km/s sampling the onset of convection and slow rotation at mid-F spectral types in great detail. Radial-velocity precision of the data (about 100m/s) is insufficient to detect planets but could indicate most SB1 systems with stellar companions. As there are already 2-3 observations per object for these newly detected binary stars, only a few additional follow-up observations will be needed to obtain constraints on orbital parameters. We identified a sample of 68 bright F-type dwarf stars which are perfect targets for future planet searches. They rotate moderately or slowly and do not show any sign of binarity, pulsations, or surface activity.

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