- ID:
- ivo://CDS.VizieR/J/ApJ/857/145
- Title:
- MagLiteS Carina II and Carina III spectroscopy
- Short Name:
- J/ApJ/857/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the Carina II (CarII) and Carina III (CarIII) dwarf galaxy candidates, recently discovered in the Magellanic Satellites Survey (MagLiteS). We identify 18 member stars in Car II, including two binaries with variable radial velocities and two RR Lyrae stars. The other 14 members have a mean heliocentric velocity v_hel_=477.2+/-1.2km/s and a velocity dispersion of {sigma}_v_=3.4_-0.8_^+1.2^km/s. Assuming Car II is in dynamical equilibrium, we derive a total mass within the half-light radius of 1.0_-0.4_^+0.8^x10^6^M_{sun}_, indicating a mass-to-light ratio of 369_-161_^+309^M_{sun}_/L_{sun}_. From equivalent width measurements of the calcium triplet lines of nine red giant branch (RGB) stars, we derive a mean metallicity of [Fe/H]=-2.44+/-0.09 with dispersion {sigma}_[Fe/H]_=0.22_-0.07_^+0.10^. Considering both the kinematic and chemical properties, we conclude that CarII is a dark-matter-dominated dwarf galaxy. For CarIII, we identify four member stars, from which we calculate a systemic velocity of v_hel_=284.6_-3.1_^+3.4^km/s. The brightest RGB member of CarIII has a metallicity of [Fe/H]=-1.97+/-0.12. Due to the small size of the Car III spectroscopic sample, we cannot conclusively determine its nature. Although these two systems have the smallest known physical separation ({Delta}d~10kpc) among Local Group satellites, the large difference in their systemic velocities, ~200km/s, indicates that they are unlikely to be a bound pair. One or both systems are likely associated with the Large Magellanic Cloud (LMC), and may remain LMC satellites today. No statistically significant excess of {gamma}-ray emission is found at the locations of Car II and Car III in eight years of Fermi-LAT data.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/511/A54
- Title:
- Magnetic cycles and radial-velocity for 8 stars
- Short Name:
- J/A+A/511/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ever increasing level of precision achieved by present and future radial velocity instruments is opening the way to the discovery of very low mass, long period planets (e.g. solar-system analogs). These systems will be detectable as low amplitude signals in radial-velocity (RV). However, an important obstacle to their detection may be the existence of stellar magnetic cycles with similar timescales. Here we present the results of a long term program to measure simultaneously radial-velocities and stellar activity indicators (CaII, H{alpha}, HeI) for a sample of stars with known activity cycles. Our results suggest that all these stellar activity indexes can be used to trace the stellar magnetic cycle in solar-type stars. Further to this, we find clear indications that different parameters of the HARPS cross-correlation function (BIS, FWHM, and Contrast) are also sensitive to activity level variations. Finally, we show that though in a few cases slight correlations or anti-correlations between radial-velocity and the activity level of the star exist, their origin is still not clear. We can however conclude that for our targets (early-K dwarfs) we do not find evidence for radial-velocity variations induced by variations of the stellar magnetic cycle with amplitudes significantly above 1m/s.
- ID:
- ivo://CDS.VizieR/J/AJ/154/140
- Title:
- MALT90 kinematic distances to molecular clumps
- Short Name:
- J/AJ/154/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using molecular-line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have estimated kinematic distances to 1905 molecular clumps identified in the ATLASGAL 870 {mu}m continuum survey over the longitude range 295{deg}<l<350{deg}. The clump velocities were determined using a flux-weighted average of the velocities obtained from Gaussian fits to the HCO^+^, HNC, and N_2_H^+^ (1-0) transitions. The near/far kinematic distance ambiguity was addressed by searching for the presence or absence of absorption or self-absorption features in 21 cm atomic hydrogen spectra from the Southern Galactic Plane Survey. Our algorithm provides an estimation of the reliability of the ambiguity resolution. The Galactic distribution of the clumps indicates positions where the clumps are bunched together, and these locations probably trace the locations of spiral arms. Several clumps fall at the predicted location of the far side of the Scutum-Centaurus arm. Moreover, a number of clumps with positive radial velocities are unambiguously located on the far side of the Milky Way at galactocentric radii beyond the solar circle. The measurement of these kinematic distances, in combination with continuum or molecular-line data, now enables the determination of fundamental parameters such as mass, size, and luminosity for each clump.
- ID:
- ivo://CDS.VizieR/J/AJ/141/131
- Title:
- Mapping the asymmetric thick disk. III.
- Short Name:
- J/AJ/141/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the first two papers of this series, Larsen et al. (1996ApJ...468L..99L) describe our faint CCD survey in the inner Galaxy and map the overdensity of thick disk stars in Quadrant 1 (Q1) to 5kpc or more along the line of sight. The regions showing the strongest excess are above the density contours of the bar in the Galactic disk. In this third paper on the asymmetric thick disk, we report on radial velocities and derived metallicity parameters for over 4000 stars in Q1, above and below the plane, and in Quadrant 4 (Q4) above the plane.
- ID:
- ivo://CDS.VizieR/VII/198
- Title:
- Mark III Catalog of Galaxy Peculiar Velocities
- Short Name:
- VII/198
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tully-Fisher and Dn-sigma distances, radial velocities, and associated catalog and observational data for the spiral, irregular, and elliptical galaxies that comprise the Mark 3 catalog are given in 5 different kinds of tables for seven separate data sets. Users interested only in the resulting distances need use only the files listed in sections 3 (Grouped spiral distance files), 4 (Elliptical galaxy distance files), and 5 (Comparison of galaxy distances).
- ID:
- ivo://CDS.VizieR/J/AJ/156/27
- Title:
- Masses & radii of 4 VLM stars in EB systems
- Short Name:
- J/AJ/156/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eclipsing binaries (EBs) with one of the companions as very low-mass stars (VLMSs; or M dwarfs) are testbeds to substantiate stellar models and evolutionary theories. Here we present four EB candidates with F-type primaries, namely, SAO 106989, HD 24465, EPIC 211682657, and HD 205403, identified from different photometry missions, SuperWASP, Kilodegree Extremely Little Telescope (KELT), Kepler 2 (K2), and Solar Terrestrial Relations Observatory (STEREO). Using the high-resolution spectrograph PRL Advanced Radial velocity Abu-sky Search at the 1.2 m telescope at Mount Abu, Rajasthan, India, we hereby report the detection of four VLMSs as companions to the four EBs. We performed spectroscopic analysis and found the companion masses to be 0.256+/-0.005, 0.233+/-0.002, 0.599+/-0.017, and 0.406+/-0.005 M_{sun}_ for SAO 106989, HD 24465, EPIC 211682657, and SAO 106989B, respectively. We determined orbital periods of 4.39790+/-0.00001, 7.19635+/-0.00002, 3.142023+/-0.000003, and 2.444949+/-0.000001 days and eccentricities of 0.248+/-0.005, 0.208+/-0.002, 0.0097+/- 0.0008, and 0.002+/-0.002 for EBs SAO 106989, HD 24465, EPIC 211682657, and HD 205403, respectively. The radii derived by modeling the photometry data are 0.326+/-0.012 R_{sun}_ for SAO 106989, 0.244+/-0.001 R_{sun}_ for HD 24465B, 0.566+/-0.005 R_{sun}_ for EPIC 211682657B, and 0.444+/-0.014 R_{sun}_ for HD 205403B. The radii of HD 24465B and EPIC 211682657B have been measured by precise Kepler photometry and are consistent with theory within the error bars. However, the radii of SAO 106989B and HD 205403B, measured by KELT and STEREO photometry, are 17%-20% higher than those predicted by theory. A brief comparison of the results of the current work is made with the M dwarfs already studied in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/96
- Title:
- Massive binaries in the LMC
- Short Name:
- J/ApJ/748/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar mass-luminosity relation is poorly constrained by observations for high-mass stars. We describe our program to find eclipsing massive binaries in the Magellanic Clouds using photometry of regions rich in massive stars, and our spectroscopic follow-up to obtain radial velocities and orbits. Our photometric campaign identified 48 early-type periodic variables, of which only 15 (31%) were found as part of the microlensing surveys. Spectroscopy is now complete for 17 of these systems, and in this paper we present analysis of the first two, LMC 172231 and ST2-28, simple detached systems of late-type O dwarfs of relatively modest masses. Our orbit analysis yields very precise masses (~2%), and we use tomography to separate the components and determine effective temperatures by model fitting, necessary for determining accurate (0.05-0.07 dex) bolometric luminosities in combination with the light-curve analysis. Our approach allows more precise comparisons with evolutionary theory than previously possible. To our considerable surprise, we find a small, but significant, systematic discrepancy: all of the stars are slightly undermassive, by typically 11% (or overluminous by 0.2 dex) compared with that predicted by the evolutionary models. We examine our approach for systematic problems, but find no satisfactory explanation. The discrepancy is in the same sense as the long-discussed and elusive discrepancy between the masses measured from stellar atmosphere analysis with the stellar evolutionary models, and might suggest that either increased rotation or convective overshooting is needed in the models.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A125
- Title:
- 54 massive companions detected with SOPHIE
- Short Name:
- J/A+A/631/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Brown-dwarfs (BD) are substellar objects with masses intermediate between planets and stars within about 13-80M_J_. While isolated brown-dwarfs are most likely produced by gravitational collapse in molecular clouds down to masses of a few M_J_, a nonnegligible fraction of low-mass companions might be formed through the planet formation channel in protoplanetary disks. The upper mass limit of objects formed within disks is still observationnally unknown, the main reason being the strong dearth of BD companions at orbital periods shorter than 10 years, a.k.a. the brown-dwarf desert. We aim at determining the best statistics of secondary companions within the 10-100M_Jup_ range within 10au from the primary star, while minimising observational bias. This can help determining the mass limit separating planet-formed from star-formed browndwarfs. Moreover, the exact shape of the BD desert in a mass-period space is still underdetermined, and can strongly constrain the companion-star interactions mechanisms at work in close binary systems at small mass ratio. We made an extensive use of the radial velocity (RV) surveys of FGK stars below 60 pc distance to the Sun and in the northern hemisphere performed with the SOPHIE spectrograph at Observatoire de Haute-Provence. We derived the Keplerian solutions of the RV variations of 54 sources. Public astrometric data of the Hipparcos and Gaia missions allowed deriving direct astrometric solution of orbital motion and constraining the mass of the companion for most sources. We introduce GASTON, a new method to derive inclination combining RVs Keplerian and astrometric excess noise from Gaia DR1. We report the discovery of 12 new BD candidates. For 5 of them, additional astrometric data led to revise their mass in the M-dwarf regime. Among the 7 remaining objects, 4 are confirmed BD companions, and 3 others are likely also in this mass regime. Moreover, we report the detection of 42 objects in the M-dwarf mass regime 90M_J_-0.52M_{sun}_. The resulting Msin i-P distribution of BD candidates shows a clear drop in the detection rate below 80-day orbital period. Above that limit, the BD desert reveals rather wet, with a uniform distribution of the Msin i. We derive a minimum BD-detection frequency around Solar-like stars of 2.0+/-0.5%.
- ID:
- ivo://CDS.VizieR/J/A+A/380/665
- Title:
- Massive dense cores with ^13^CO J=1-0 lines
- Short Name:
- J/A+A/380/665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports ^13^CO J=1-0 line observations toward 107 IRAS or H2O maser sources with the 13.7m telescope of the Purple Mountain Observatory (PMO). Parameters of emission components are obtained and the profile characteristics are identified. Table1 lists the observed results. It contains source name and its coordinates. ^13^CO line parameters and profile characteristics are given out. Distance, IRAS color indices and bolometric luminosity are also presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/74
- Title:
- 2MASS view of Sgr dSph. VII. Kinematics
- Short Name:
- J/ApJ/756/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled a large-area spectroscopic survey of giant stars in the Sagittarius (Sgr) dwarf galaxy core. Using medium resolution (R~15000), multifiber spectroscopy we have measured velocities of these stars, which extend up to 12{deg} from the galaxy's center (3.7 core radii or 0.4 times the King limiting radius). From these high-quality spectra we identify 1310 Sgr members out of 2296 stars surveyed, distributed across 24 different fields across the Sgr core. Additional slit spectra were obtained of stars bridging from the Sgr core to its trailing tail. Our systematic, large-area sample shows no evidence for significant rotation, a result at odds with the ~20km/s rotation required as an explanation for the bifurcation seen in the Sgr tidal stream; the observed small (<=4km/s) velocity trend primarily along the major axis is consistent with models of the projected motion of an extended body on the sky with no need for intrinsic rotation. The Sgr core is found to have a flat velocity dispersion (except for a kinematically colder center point) across its surveyed extent and into its tidal tails, a property that matches the velocity dispersion profiles measured for other Milky Way dwarf spheroidal (dSph) galaxies. We comment on the possible significance of this observed kinematical similarity for the dynamical state of the other classical Milky Way dSphs in light of the fact that Sgr is clearly a strongly tidally disrupted system.