- ID:
- ivo://CDS.VizieR/J/AJ/123/3356
- Title:
- Palomar/MSU nearby star spectroscopic survey. III.
- Short Name:
- J/AJ/123/3356
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution echelle spectroscopy of 676 nearby M dwarfs. Our measurements include radial velocities, equivalent widths of important chromospheric emission lines, and rotational velocities for rapidly rotating stars. We identify several distinct groups by their H{alpha} properties and investigate variations in chromospheric activity among early (M0-M2.5) and mid (M3-M6) dwarfs. Using a volume-limited sample together with a relationship between age and chromospheric activity, we show that the rate of star formation in the immediate solar neighborhood has been relatively constant over the last 4Gyr. In particular, our results are inconsistent with recent large bursts of star formation. We use the correlation between H{alpha} activity and age as a function of color to set constraints on the properties of L and T dwarf secondary components in binary systems. We also identify a number of interesting stars, including rapid rotators, radial velocity variables, and spectroscopic binaries.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/784/156
- Title:
- Parallaxes for 1507 nearby mid-to-late M dwarfs
- Short Name:
- J/ApJ/784/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The MEarth survey is a search for small rocky planets around the smallest, nearest stars to the Sun as identified by high proper motion with red colors. We augmented our planetary search time series with lower cadence astrometric imaging and obtained two million images of approximately 1800 stars suspected to be mid-to-late M dwarfs. We fit an astrometric model to MEarth's images for 1507 stars and obtained trigonometric distance measurements to each star with an average precision of 5mas. Our measurements, combined with the Two Micron All Sky Survey photometry, allowed us to obtain an absolute K_s_ magnitude for each star. In turn, this allows us to better estimate the stellar parameters than those obtained with photometric estimates alone and to better prioritize the targets chosen to monitor at high cadence for planetary transits. The MEarth sample is mostly complete out to a distance of 25pc for stars of type M5.5V and earlier, and mostly complete for later type stars out to 20pc. We find eight stars that are within 10pc of the Sun for which there did not exist a published trigonometric parallax distance estimate. We release with this work a catalog of the trigonometric parallax measurements for 1507 mid-to-late M dwarfs, as well as new estimates of their masses and radii.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A58
- Title:
- PDF Atlas and spectra of FeH molecule in LHS 2
- Short Name:
- J/A+A/523/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas for the iron-hydride molecule (FeH) in the z-range (990nm to 1076.6nm). We used high-resolution CRIRES spectra of the M-dwarf GJ1002, which is an ideal target for the investigation of FeH, because it is only very slow rotating (<3km/s) and exhibits only weak magnetic fields. The identified lines stem mainly from the (0-0) and (1-1) vibronic transitions, but also from the (1-0), (2-1), (2-2), (3-2), and (4-3) transitions. For the confirmation of the identifications, we used means of statistic and cross-correlation as well as the line intensities. We corrected the theoretical positions if needed and scaled the line intensities till they match the observations.
- ID:
- ivo://CDS.VizieR/J/other/Ap/64.27
- Title:
- Periodic variables in Catalina and LINEAR
- Short Name:
- J/other/Ap/64.27
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In this study we continue spectral class determinations for large number of optically faint periodic variables taken from the Catalina Surveys Data Release 1 (CSDR1)and LINEAR data sets. Spectral classes and physical parameters are presented for 1184 periodic variables with periods P>=10 days, taken from modern large sky area spectroscopic and photometric databases, including LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope), SDSS(Sloan Digital Sky Survey), the Hamburg Quasar Survey(HQS)m the Hamburg /ESO Survey (HES), and Gaia Data Release 2 (DR2). In Gaia DR2 catalogue, luminosities are presented for 276 objects and radial velocities (RV) for 108. Spectral classes were confirmed for more than 650 objects. The majority of the variables are found to be F, G, K, M dwarfs and giants, a few dozen carbon (C) stars (N-type Asymptotic Giant Branch (AGB) stars), and a few S stars. Some periodic variables are blue objects, such as B and A stars. The periods are in the range 10<=P<=1504 days and Catalina magnitudes in range 11.5<=V<=20.0mag. Finding new and faint evolved AGB stars in the halo of our Galaxy is the first priority. A catalogue containing multi-parameter data for 1184 periodic variables from modern astronomical databases has been generated.
- ID:
- ivo://CDS.VizieR/J/A+A/439/1137
- Title:
- PHOENIX model chromospheres of M dwarfs
- Short Name:
- J/A+A/439/1137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extensive identification catalog of chromospheric emission lines in the optical range. The data were obtained with ESO's Kueyen telescope equipped with the UVES spectrograph from March, 13th to 16th in 2002. The instrument was operated in dichroic mode (spectral coverage from 3030 to 3880 and from 4580 to 6680{AA}). The data for the stars Prox Cen, UV Ceti and LHS 292 were obtained with the same instrument in winter 2000/2001 with a monochroic setup providing only the blue part of the spectrum. We tabulated measured wavelength, equivalent width (EW) and FWHM for every line and star and also provide the rest wavelength from the Moore catalog which was used for identification (Moore 1972). Few lines were identified with the NIST database. The spectra were all corrected for radial velocity besides Kelu-1, DENIS-P J1058.7-1548 and 2MASSI J1315309-264951. DENIS-P J1058.7-1548 has no detected lines, and therefore no data in the table.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1484
- Title:
- Photometry and spectroscopy in IC 2391
- Short Name:
- J/ApJ/706/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar and substellar mass function (MF) of the open cluster IC 2391, plus its radial dependence, and use this to put constraints on the formation mechanism of brown dwarfs (BDs). Our multi-band optical and infrared photometric survey with spectroscopic follow-up covers 11deg^2^, making it the largest survey of this cluster to date. From our preliminary spectroscopic follow-up, to confirm BD status and cluster membership, we find that all candidates are M dwarfs (in either the field or the cluster), demonstrating the efficiency of our photometric selection method in avoiding contaminants (e.g., red giants). About half of our photometric candidates for which we have spectra are spectroscopically confirmed as cluster members; two are new spectroscopically confirmed BD members of IC 2391.
- ID:
- ivo://CDS.VizieR/J/AJ/149/166
- Title:
- Photometry and spectroscopy of HATS-6
- Short Name:
- J/AJ/149/166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by the HATSouth survey of HATS-6b, an extrasolar planet transiting a V=15.2mag, i=13.7mag M1V star with a mass of 0.57M_{Sun}_ and a radius of 0.57R_{sun}_ . HATS-6b has a period of P=3.3253d, mass of M_p_=0.32M_J_, radius of R_p_=1.00R_J_, and zero-albedo equilibrium temperature of T_eq_=712.8+/-5.1K. HATS-6 is one of the lowest mass stars known to host a close-in gas giant planet, and its transits are among the deepest of any known transiting planet system. We discuss the follow-up opportunities afforded by this system, noting that despite the faintness of the host star, it is expected to have the highest K-band S/N transmission spectrum among known gas giant planets with T_eq_<750K. In order to characterize the star we present a new set of empirical relations between the density, radius, mass, bolometric magnitude, and V-, J-, H- and K-band bolometric corrections for main sequence stars with M<0.80M_{Sun}_, or spectral types later than K5. These relations are calibrated using eclipsing binary components as well as members of resolved binary systems. We account for intrinsic scatter in the relations in a self-consistent manner. We show that from the transit-based stellar density alone it is possible to measure the mass and radius of a ~0.6M_{Sun}_ star to ~7 and ~2% precision, respectively. Incorporating additional information, such as the V-K color, or an absolute magnitude, allows the precision to be improved by up to a factor of two.
- ID:
- ivo://CDS.VizieR/J/AJ/147/76
- Title:
- Photometry of M giant candidates in the Milky Way
- Short Name:
- J/AJ/147/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 404 M giant candidates found in the UKIRT Infrared Deep Sky Survey (UKIDSS). The 2400deg^2^ available in the UKIDSS Large Area Survey Data Release 8 resolve M giants through a volume four times larger than that of the entire Two Micron All Sky Survey. Combining near-infrared photometry with optical photometry and proper motions from the Sloan Digital Sky Survey yields an M giant candidate catalog with less M dwarf and quasar contamination than previous searches for similarly distant M giants. Extensive follow-up spectroscopy of this sample will yield the first map of our Galaxy's outermost reaches over a large area of sky. Our initial spectroscopic follow-up of ~30 bright candidates yielded the positive identification of five M giants at distances ~20-90kpc. Each of these confirmed M giants have positions and velocities consistent with the Sagittarius stream. The fainter M giant candidates in our sample have estimated photometric distances ~200kpc (assuming [Fe/H]=0.0), but require further spectroscopic verification. The photometric distance estimates extend beyond the Milky Way's virial radius, and increase by ~50% for each 0.5dex decrease in assumed [Fe/H]. Given the number of M giant candidates, initial selection efficiency, and volume surveyed, we loosely estimate that at least one additional Sagittarius-like accretion event could have contributed to the hierarchical build-up of the Milky Way's outer halo.
- ID:
- ivo://CDS.VizieR/J/ApJ/721/412
- Title:
- Photometry of polar CV* 1RXS J173006.4+033813
- Short Name:
- J/ApJ/721/412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 1RXS J173006.4+033813, a polar cataclysmic variable with a period of 120.21 minutes. The white dwarf primary has a magnetic field of B=42^+6^_-5_MG and the secondary is an M3 dwarf. The system shows highly symmetric double-peaked photometric modulation in the active state as well as in quiescence. These arise from a combination of cyclotron beaming and ellipsoidal modulation. The projected orbital velocity of the secondary is K_2_=390+/-4km/s. We place an upper limit of 830+/-65pc on the distance.
- ID:
- ivo://CDS.VizieR/J/AJ/155/257
- Title:
- Photometry & RV follow-up observations of K2-18
- Short Name:
- J/AJ/155/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet that was first discovered by the K2 mission and later confirmed with Spitzer Space Telescope observations. With a radius of ~2 R_{Earth}_ and an orbital period of ~33 days, the planet lies in the temperate zone of its host star and receives stellar irradiation similar to that of Earth. Here we perform radial velocity follow-up observations with the visual channel of CARMENES with the goal of determining the mass and density of the planet. We measure a planetary semi-amplitude of K_b_~3.5 m/s and a mass of M_b_~9 M_{Earth}_, yielding a bulk density around {rho}_b_~4 g/cm^3^. This indicates a low-mass planet with a composition consistent with a solid core and a volatile-rich envelope. A signal at 9 days was recently reported using radial velocity measurements taken with the HARPS spectrograph. This was interpreted as being due to a second planet. We see a weaker, time- and wavelength-dependent signal in the CARMENES data set and thus favor stellar activity for its origin. K2-18 b joins the growing group of low-mass planets detected in the temperate zone of M dwarfs. The brightness of the host star in the near-infrared makes the system a good target for detailed atmospheric studies with the James Webb Space Telescope.
