- ID:
- ivo://CDS.VizieR/J/AJ/152/24
- Title:
- Trigonometric parallaxes of 134 low-mass stars
- Short Name:
- J/AJ/152/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report trigonometric parallaxes for 134 low-mass stars and brown dwarfs, of which 38 have no previously published measurement and 79 more have improved uncertainties. Our survey focused on nearby targets, so 119 are closer than 30pc. Of the 38 stars with new parallaxes, 14 are within 20pc and seven are likely brown dwarfs (spectral types later than L0). These parallaxes are useful for studies of kinematics, multiplicity, and spectrophotometric calibration. Two objects with new parallaxes are confirmed as young stars with membership in nearby young moving groups: LP 870-65 in AB Doradus and G161-71 in Argus. We also report the first parallax for the planet-hosting star GJ3470; this allows us to refine the density of its Neptune-mass planet. T-dwarf 2MASSJ12590470-4336243, previously thought to lie within 4pc, is found to be at 7.8pc, and the M-type star 2MASSJ01392170-3936088 joins the ranks of nearby stars as it is found to be within 10pc. Five stars that are overluminous and/or too red for their spectral types are identified and deserve further study as possible young stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/885/9
- Title:
- Triple system HD 28363; RVel and visual observations
- Short Name:
- J/ApJ/885/9
- Date:
- 15 Mar 2022 07:55:42
- Publisher:
- CDS
- Description:
- The star HD28363 in the Hyades cluster has been known for over a century as a visual binary with a period of 40yr. The secondary is, in turn, a single-lined spectroscopic binary with a 21day period. Here we report extensive spectroscopic monitoring of this hierarchical triple system that reveals the spectral lines of the third star for the first time. Combined with astrometric information, this makes it possible to determine the dynamical masses of all three stars. Only six other binaries in the Hyades have had their individual component masses determined dynamically. We infer the properties of the system by combining our radial-velocity measurements with visual observations, lunar occultation measurements, and with proper motions from the Hipparcos and Gaia missions that provide a constraint on the astrometric acceleration. We derive a mass of 1.341_-0.024_^+0.026^M{odot} for the visual primary, and 1.210{+/-}0.021 and 0.781{+/-}0.014 M{sun} for the other two stars. These measurements along with those for the other six systems establish an empirical mass-luminosity relation in the Hyades that is in broad agreement with current models of stellar evolution for the known age and chemical composition of the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2915
- Title:
- Triple systems (cool primary + hot binary)
- Short Name:
- J/AJ/127/2915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the course of comparing parameters of evolved cool star plus hot main-sequence star binaries with theoretical isochrones, some discrepancies are found between implied stellar masses and the spectroscopic binary mass function or the measured angular separation. These are naturally explained if there is a third star in the system. Multiplicity is also required to explain some comparisons of "cool plus hot binary" IUE and optical spectral energy distribution analysis with measured flux ratios, especially Tycho's two-color photometry of separate components. Out of a sample of 136 cool-plus-hot binary star systems under study, measurements are now indicating several systems considered double (HD 5373, 23089, 26673, 29094, 49126, 71129, 149379, 179002, 187299), and probably a few others (including HD 136415), to have at least three stellar components. Several other cases of suspected triple systems are confirmed. For comparison, there are eight known triples included in the project. In all, about 25% of the systems contain three or more components within a few arcseconds. Estimated separations are provided, which may be of use when not known from interferometry. In general, the triple systems have one post-main-sequence component and two upper main-sequence components, usually revolving around each other. One new triple system, HD 149379, has as its middle component an F giant in the brief first crossing of the Hertzsprung gap.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/1411
- Title:
- Trumpler 5 photometric BV catalog
- Short Name:
- J/MNRAS/446/1411
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a long-term programme, we analyse the evolutionary status and properties of the old and populous open cluster Trumpler 5 (Tr 5), located in the Galactic anticentre direction, almost on the Galactic plane. Tr 5 was observed with Wide Field Imager@MPG/ESO Telescope using the Bessel U, B, and V filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram (CMD) method, i.e. the direct comparison of the observational CMD with a library of synthetic CMDs generated with different stellar evolution sets (Padova, FRANEC, and FST). Age, reddening, and distance are derived through the synthetic CMD method using stellar evolutionary models with subsolar metallicity (Z=0.004 or Z=0.006). Additional spectroscopic observations with Ultraviolet VLT Echelle Spectrograph@Very Large Telescope of three red clump stars of the cluster were used to determine more robustly the chemical properties of the cluster. Our analysis shows that Tr 5 has subsolar metallicity, with [Fe/H]=-0.403+/-0.006 dex (derived from spectroscopy), age between 2.9 and 4 Gyr (the lower age is found using stellar models without core overshooting), reddening E(B-V) in the range 0.60-0.66 mag complicated by a differential pattern (of the order of ~+/-0.1mag), and distance modulus (m-M)_0_=12.4+/-0.1mag.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/610
- Title:
- 47 Tuc sub-giant branch chemical abundances
- Short Name:
- J/MNRAS/459/610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The globular cluster 47 Tuc exhibits a complex sub-giant branch (SGB) with a faint-SGB comprising only about the 10 per cent of the cluster mass and a bright-SGB hosting at least two distinct populations. We present a spectroscopic analysis of 62 SGB stars including 21 faint-SGB stars. We thus provide the first chemical analysis of the intriguing faint-SGB population and compare its abundances with those of the dominant populations. We have inferred abundances of Fe, representative light elements C, N, Na, and Al, {alpha} elements Mg and Si for individual stars. Oxygen has been obtained by co-adding spectra of stars on different sequences. In addition, we have analysed 12 stars along the two main RGBs of 47 Tuc. Our principal results are (i) star-to-star variations in C/N/Na among RGB and bright-SGB stars; (ii) substantial N and Na enhancements for the minor population corresponding to the faint-SGB; (iii) no high enrichment in C+N+O for faint-SGB stars. Specifically, the C+N+O of the faint-SGB is a factor of 1.1 higher than the bright-SGB, which, considering random (+/-1.3) plus systematic errors (+/-0.3), means that their C+N+O is consistent within observational uncertainties. However, a small C+N+O enrichment for the faint-SGB, similar to what predicted on theoretical ground, cannot be excluded. The N and Na enrichment of the faint-SGB qualitatively agrees with this population possibly being He-enhanced, as suggested by theory. The iron abundance of the bright and faint-SGB is the same to a level of ~0.10dex, and no other significant difference for the analysed elements has been detected.
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/2347
- Title:
- Tully-Fisher relation for SDSS galaxies
- Short Name:
- J/MNRAS/417/2347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we derive scaling relations between photometric observable quantities and disc galaxy rotation velocity V_rot_ or Tully-Fisher relations (TFRs). Our methodology is dictated by our purpose of obtaining purely photometric, minimal-scatter estimators of V_rot_ applicable to large galaxy samples from imaging surveys. To achieve this goal, we have constructed a sample of 189 disc galaxies at redshifts z<0.1 with long-slit H{alpha} spectroscopy from Pizagno et al. (2007, Cat. J/AJ/134/945) and new observations. By construction, this sample is a fair subsample of a large, well-defined parent disc sample of ~170000 galaxies selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7).
- ID:
- ivo://CDS.VizieR/J/AJ/134/945
- Title:
- Tully-Fisher relation for SDSS galaxies
- Short Name:
- J/AJ/134/945
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the relation between galaxy luminosity and disk circular velocity (the Tully-Fisher [TF] relation), in the g, r, i, and z bands, for a broadly selected sample of galaxies from the Sloan Digital Sky Survey, with the goal of providing well-defined observational constraints for theoretical models of galaxy formation. The input sample of 234 galaxies has a roughly flat distribution of absolute magnitudes in the range -18.5>M_r_>-22, and our only morphological selection is an isophotal axis ratio cut b/a<=0.6 to allow accurate inclination corrections. Long-slit spectroscopy from the Calar Alto and MDM observatories yields usable Halpha rotation curves for 162 galaxies (69%), with a representative color and morphology distribution. We define circular velocities V_80_ by evaluating the rotation curve at the radius containing 80% of the i-band light.
3878. Tuorla Quasar Monitoring
- ID:
- ivo://CDS.VizieR/J/A+AS/143/357
- Title:
- Tuorla Quasar Monitoring
- Short Name:
- J/A+AS/143/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observations presented in table 3 were made by using the 1.03m Dall-Kirkham-type telescope (f/8.45) of Tuorla Observatory with a SBIG ST-8 CCD-camera and a standard V-band filter. Table 4 includes data (B-, V- , and R-bands) observed at the Nordic Optical Telescope (NOT) on La Palma. Corrections for dark-current effects, additive effects (bias) and multiplicative effects (flatfield) were applied. Due to the relatively small field of view of the telescope separate frames of comparison stars were exposed for Mrk 421 and 4C 29.45. For the other objects normal differential photometry methods were applied. Exposure times with the Tuorla 1.03 meter telescope were between 60 and 240 seconds for objects brighter than 16 mag. For fainter objects, we have combined several exposures to achieve a sufficiently high signal to noise ratio.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A32
- Title:
- Turin-SyCAT, Seyferts multifrequency catalog
- Short Name:
- J/A+A/659/A32
- Date:
- 02 Mar 2022 06:48:51
- Publisher:
- CDS
- Description:
- We present the first release of Turin-SyCAT, a multifrequency catalog of Seyfert galaxies. We selected Seyfert galaxies considering criteria based on radio, infrared, and optical properties and starting from sources belonging to hard X-ray catalogs and surveys. We visually inspected optical spectra available for all selected sources. We adopted homogeneous and stringent criteria in the source selection aiming at reducing the possible contamination from other source classes. Our final catalog includes 351 Seyfert galaxies distinguished in 233 type 1 and 118 type 2. Type 1 Seyfert galaxies appear to have mid-IR colors similar to blazars, but are distinguished from them by their radio-loudness. Additionally, Seyfert 2 galaxies have mid-IR colors more similar to quasars than BL Lac objects. As expected from their spectral properties, type 1 and 2 Seyfert galaxies show a clear distinction when using the u-r color. Finally, we found a tight correlation between the mid-IR fluxes at both 12 and 22 um (i.e., F12 and F22, respectively) and hard X-ray fluxes between 15 and 150 keV. Both Seyfert types appear to follow the same trend and share similar values of the ratios of F12 and F22 to FHX in agreement with expectations of the AGN unification scenario. As future perspectives, the Turin-SyCAT will then be used to search for heavily obscured Seyfert galaxies among unidentified hard X-ray sources, given the correlation between mid-IR and hard X-rays, and to investigate their large-scale environments.
- ID:
- ivo://CDS.VizieR/J/AJ/159/105
- Title:
- Two new stellar associations in vicinity of the Sun
- Short Name:
- J/AJ/159/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we report the discovery of two new stellar associations in close vicinity of the Sun at roughly 180 and 150pc. These two associations, u-Tau assoc and e-Tau assoc, were detected based on their clustering in a multi-dimensional parameter space including {alpha}, {delta}, {mu}_{alpha}_, {mu}_{delta}_, and \bar{omega} of Gaia. The fitting of pre-main-sequence model isochrones in their color-magnitude diagrams suggests that the two associations are of about 50Myr old and the group members lower than ~0.8M_{sun}_ are at the stage of post-T Tauri.
