- ID:
- ivo://CDS.VizieR/J/AJ/147/34
- Title:
- SpeX library of L-type dwarfs
- Short Name:
- J/AJ/147/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of the L dwarf WISE J174102.78-464225.5, which was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its near-infrared spectrum and its red near-infrared colors (J-K_S_=2.35+/-0.08mag) are indicative of a young age. Via comparison to spectral standards and other red L dwarfs, we estimate a near-infrared spectral type of L7+/-2 (pec). From a comparison to spectral and low-mass evolutionary models, we determine self-consistent effective temperature, logg, age, and mass values of 1450+/-100K, 4.0+/-0.25 (cm/s2), 10-100Myr, and 4-21M_Jup_, respectively. With an estimated distance of 10-30pc, we explore the possibility that WISE J174102.78-464225.5 belongs to one of the young nearby moving groups via a kinematic analysis and we find potential membership in the {beta} Pictoris or AB Doradus associations. A trigonometric parallax measurement and a precise radial velocity can help to secure its membership in either of these groups.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/651/502
- Title:
- Spitzer IRAC photometry of M, L, and T dwarfs
- Short Name:
- J/ApJ/651/502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a program to acquire photometry for 86 late M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of these cool dwarfs in various color-color and color-magnitude diagrams composed of near-IR and IRAC data.
- ID:
- ivo://CDS.VizieR/J/ApJ/653/675
- Title:
- Spitzer 24{mu}m photometry of A dwarfs
- Short Name:
- J/ApJ/653/675
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 24 and/or 70um measurements of ~160 A-type main-sequence stars using the Multiband Imaging Photometer for Spitzer (MIPS).
- ID:
- ivo://CDS.VizieR/J/ApJ/620/1010
- Title:
- Spitzer 24{mu}m photometry of A dwarfs
- Short Name:
- J/ApJ/620/1010
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new Spitzer 24{mu}m photometry of 76 main-sequence A-type stars. We combine these results with previously reported Spitzer 24{mu}m data and 24 and 25{mu}m photometry from the Infrared Space Observatory and the Infrared Astronomy Satellite. The result is a sample of 266 stars with mass close to 2.5M_Sun_ all detected to at least the ~7{sigma} level relative to their photospheric emission.
- ID:
- ivo://CDS.VizieR/J/AJ/144/135
- Title:
- Spitzer 24{mu}m photometry of Hipparcos F stars
- Short Name:
- J/AJ/144/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a study of debris disks around F stars in order to explore correlations between rotation, stellar winds, and circumstellar disks. We obtained new 24{mu}m photometry from the Multiband Imaging Photometer for Spitzer (MIPS) camera for a sample of 188 relatively nearby F dwarfs with various rotation rates and optical colors, and combined it with archival MIPS data for 66 more F stars, as well as Wide-field Infrared Survey Explorer data for the entire sample, plus 9 more F stars. Based on the objects' K_s_-[24] and [3.4]-[22] colors, we identify 22 stars in our sample as having 22 and/or 24{mu}m excesses above our detection limit, 13 of which are new discoveries. Our overall disk detection rate is 22/263, or 8%, consistent with previous determinations of disk fractions in the solar neighborhood. While fast-rotating stars are expected to have strong winds capable of efficiently removing dust, we find no correlation between rotational velocity and infrared excess. Similarly, we find no significant difference in excess detection rate between late-type F stars, which have convective surfaces, and early-type F stars, which have fully radiative envelopes. However, the essentially unknown range of ages in this sample may be washing out any effects relating rotation, winds, and disks.
- ID:
- ivo://CDS.VizieR/J/ApJ/679/720
- Title:
- Spitzer observations of the Hyades
- Short Name:
- J/ApJ/679/720
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Spitzer Space Telescope to search for infrared excess at 24, 70, and 160um due to debris disks around a sample of 45 FGK-type members of the Hyades. We supplement our observations with archival 24 and 70um Spitzer data of an additional 22 FGK-type and 11 A-type Hyades members in order to provide robust statistics on the incidence of debris disks at 625Myr of age, an era corresponding to the late heavy bombardment in the solar system. We find that none of the 67 FGK-type stars in our sample show evidence for a debris disk, while 2 out of the 11 A-type stars do. This difference in debris disk detection rate is likely to be due to a sensitivity bias in favor of early-type stars. The fractional disk luminosity, L_dust_/L_*_, of the disks around the two A-type stars is ~4x10^-5^, a level that is below the sensitivity of our observations toward the FGK-type stars. However, our sensitivity limits for FGK-type stars are able to exclude, at the 2{sigma} level, frequencies higher than 12% and 5% of disks with L_dust_/L_*_>1x10^-4^ and L_dust_/L_*_>5x10^-4^, respectively. We also use our sensitivity limits and debris disk models to constrain the maximum mass of dust, as a function of distance from the stars, that could remain undetected around our targets.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/159
- Title:
- Statistical analysis of exoplanet surveys
- Short Name:
- J/ApJ/794/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections ({kappa} And b, two ~60 M_J_ brown dwarf companions in the Pleiades, PZ Tel B, and CD-35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statistical method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ~30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ~5 M_J_, with a single power-law distribution. We find that p(M,a){prop.to}M^-0.65+/-0.60^a^-0.85+/-0.39^ (1{sigma} errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M_J_ companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A128
- Title:
- Stellar abundances of neutron-capture elements
- Short Name:
- J/A+A/552/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to present and discuss the observations of the iron peak (Fe, Ni) and neutron-capture element (Y, Zr, Ba, La, Ce, Nd, Sm, and Eu) abundances for 276 FGK dwarfs, located in the galactic disk with metallicity -1<[Fe/H]<+0.3. Atmospheric parameters and chemical composition of the studied stars were determined from an high resolution, high signal-to-noise echelle spectra obtained with the echelle spectrograph ELODIE at the Observatoire de Haute-Provence (France). Effective temperatures were estimated by the line depth ratio method and from the H{alpha} line-wing fitting. Surface gravities (logg) were determined by parallaxes and the ionization balance of iron. Abundance determinations were carried out using the LTE approach, taking the hyperfine structure for Eu into account, and the abundance of Ba was computed under the NLTE approximation. We are able to assign most of the stars in our sample to the substructures of the Galaxy thick disk, thin disk, or Hercules stream according to their kinematics. The classification of 27 stars is uncertain. For most of the stars in the sample, the abundances of neutron-capture elements have not been measured earlier. For all of them, we provide the chemical composition and discuss the contribution from different nucleosynthesis processes.
- ID:
- ivo://CDS.VizieR/J/A+A/299/755
- Title:
- Stellar evolution. II. Post-AGB
- Short Name:
- J/A+A/299/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of evolutionary tracks for central stars of planetary nebulae in the range from 0.53 to 0.94M_{sun}_. These models are based on extensive stellar evolution calculations for initial masses between 1 and 7M_{sun}_ which have been carried out all the way from the main sequence through the AGB towards the stage of white dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/430/1143
- Title:
- Stellar magnetic rotational phase curves
- Short Name:
- J/A+A/430/1143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetized stars usually exhibit periodic variations of the effective (longitudinal) magnetic field B_e_ caused by their rotation. We present a catalog of magnetic rotational phase curves, B_e_ vs. the rotational phase phi, and tables of their parameters for 136 stars on the main sequence and above it. Phase curves were obtained by the least squares fitting of sine wave or double wave functions to the available B_e_ measurements, which were compiled from the existing literature. Most of the catalogued objects are chemically peculiar A and B type stars (127 stars). For some stars we also improved or determined periods of their rotation. We discuss the distribution of parameters describing magnetic rotational phase curves in our sample.
