- ID:
- ivo://CDS.VizieR/J/AJ/162/14
- Title:
- Astrometry & radial velocity, Alpha Centauri system
- Short Name:
- J/AJ/162/14
- Date:
- 14 Mar 2022 06:46:54
- Publisher:
- CDS
- Description:
- Alpha Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its habitable zone. Here, we describe initial results from an Atacama Large Millimeter/submillimeter Array (ALMA) program to search for planets in the {alpha} Cen AB system using differential astrometry at millimeter wavelengths. Our initial results include new absolute astrometric measurements of the proper motion, orbital motion and parallax of the {alpha} Cen system. These lead to an improved knowledge of the physical properties of both {alpha} Cen A and B. Our estimates of ALMA's relative astrometric precision suggest that we will ultimately be sensitive to planets of a few tens of Earth mass in orbits from 1 to 3au, where stable orbits are thought to exist.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PAZh/38/571
- Title:
- Astrophysical parameters for 593 open clusters
- Short Name:
- J/PAZh/38/571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on published data, we have compiled a catalogue of fundamental astrophysical parameters for 593 open clusters of the Galaxy. In particular, the catalogue provides the Galactic orbital elements for 500 clusters, the masses, central concentrations, and ellipticities for 424 clusters, the metallicities for 264 clusters, and the relative magnesium abundances for 56 clusters. We describe the sources of initial data and estimate the errors in the investigated parameters. The selection effects are discussed. The chemical and kinematical properties of the open clusters and field thin-disk stars are shown to differ. We provide evidence for the heterogeneity of the population of open star clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/156/61
- Title:
- A study of the H{alpha} variability of Be stars
- Short Name:
- J/AJ/156/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the results of 4 years of high-resolution spectral observations of 69 emission-line stars, 54 of them being newly discovered sources. We classified the stars on the basis of their position in the two-color IR diagram and some additional criteria: shape and width of the H{alpha} profile, presence of He lines, proper motion and parallax, membership to open cluster and associations. Sixty of our targets turned out to be Be stars. We also found four late giants, four pre-MS stars, and one late dwarf. The H{alpha} emission profiles of our Be stars range from single peaked to typical shell profiles that can also be highly asymmetric or single-peaked profiles with a narrow absorption core. The emission profiles appear almost constant with time or highly variable in intensity and in their V/R ratio. The detected long-term variability of the H{alpha} emission is important for investigating the on/off switch phenomenon of Be stars. Our study led to an increase of the number of the emission-line stars of 16 open clusters.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/115
- Title:
- A study of the open cluster NGC 6811
- Short Name:
- J/PAZh/25/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 191 individual measurements of radial velocities made with CORAVEL-type spectrometer are presented for 60 stars in the large region of NGC 6811 open cluster. Photoelectric UBVR magnitudes are given for 117 stars - members of the cluster by proper motions. Spectral classification of these stars is taken from Straizys and Kazlauskas (1993BaltA...2....1S).
- ID:
- ivo://CDS.VizieR/J/AJ/127/1567
- Title:
- Asymmetric thick disk. II. Kinematics
- Short Name:
- J/AJ/127/1567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a kinematic signature associated with the observed asymmetry in the distribution of thick-disk/inner halo stars interior to the solar circle described in Paper I (Parker et al., 2003AJ....126.1346P). In that paper, we found a statistically significant excess (20%-25%) of stars in quadrant I (l~20{deg}-55{deg}) both above and below the plane (b~+/-25{deg} to b~+/-45{deg}) compared with the complementary region in quadrant IV. We have measured Doppler velocities for 741 stars, selected according to the same magnitude and color criteria, in the direction of the asymmetry and in the corresponding fields in quadrant IV. We have also determined spectral types and metallicities measured from the same spectra.
116. ATLAS3D project. I.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/813
- Title:
- ATLAS3D project. I.
- Short Name:
- J/MNRAS/413/813
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ATLAS^3D^ project is a multiwavelength survey combined with a theoretical modelling effort. The observations span from the radio to the millimetre and optical, and provide multicolour imaging, two-dimensional kinematics of the atomic (HI), molecular (CO) and ionized gas (H{beta}, [OIII] and [NI]), together with the kinematics and population of the stars (H{beta}, Fe5015 and Mgb), for a carefully selected, volume-limited (1.16x10^5^Mpc^3^) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D<42Mpc, |DE-29{deg}|<35{deg}, |b|>15{deg}) morphologically selected ETGs extracted from a parent sample of 871 galaxies (8 per cent E, 22 per cent S0 and 70 per cent spirals) brighter than M_K_<-21.5mag (stellar mass M_*_>~6x10^9^M_{sun}_).
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/888
- Title:
- ATLAS3D project. III.
- Short Name:
- J/MNRAS/414/888
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide a census of the apparent stellar angular momentum within one effective radius of a volume-limited sample of 260 early-type galaxies (ETGs) in the nearby Universe, using the integral-field spectroscopy obtained in the course of the ATLAS3D project. We exploit the {lambda}_R_ parameter (previously used via a constant threshold value of 0.1) to characterize the existence of two families of ETGs: slow rotators which exhibit complex stellar velocity fields and often include stellar kinematically distinct cores, and fast rotators which have regular velocity fields. Our complete sample of 260 ETGs leads to a new criterion to disentangle fast and slow rotators which now includes a dependency on the apparent ellipticity {epsilon}.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A146
- Title:
- ATLASGAL cold high-mass clumps with NH_3_
- Short Name:
- J/A+A/544/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The APEX Telescope Large Area Survey: The Galaxy (ATLASGAL) is an unbiased continuum survey of the inner Galactic disk at 870 micron. It covers +/-60{deg} in Galactic longitude and aims to find all massive clumps at various stages of high-mass star formation in the inner Galaxy, particularly the earliest evolutionary phases. We aim to determine properties such as the gas kinetic temperature and dynamics of new massive cold clumps found by ATLASGAL. Most importantly, we derived their kinematical distances from the measured line velocities. We observed the ammonia (J,K)=(1,1) to (3,3) inversion transitions toward 862 clumps of a flux-limited sample of submm clumps detected by ATLASGAL and extracted ^13^CO(1-0) spectra from the Galactic Ring Survey (GRS). We determined distances for a subsample located at the tangential points (71 sources) and for 277 clumps whose near/far distance ambiguity is resolved. Most ATLASGAL clumps are cold with rotational temperatures from 10-30K with a median of 17K. They have a wide range of NH_3_ linewidths (1-7km/s with 1.9km/s as median, which by far exceeds the thermal linewidth, as well as a broad distribution of high column densities from 10^14^ to 10^16^cm^-2^ (median of 2x10^15^cm^-2^) with an NH_3_ abundance in the range of 5 to 30x10^-8^. ATLASGAL sources are massive, >100M_{sun}_, and a fraction of clumps with a broad linewidth is in virial equilibrium. We found an enhancement of clumps at Galactocentric radii of 4.5 and 6kpc. The comparison of the NH_3_ lines as high-density probes with the GRS ^13^CO emission as low-density envelope tracer yields broader linewidths for ^13^CO than for NH_3_. The small differences in derived clump velocities between NH_3_ (representing dense core material) and ^13^CO (representing more diffuse molecular cloud gas) suggests that the cores are essentially at rest relative to the surrounding giant molecular cloud. The high detection rate (87%) confirms ammonia as an excellent probe of the molecular content of the massive, cold clumps revealed by ATLASGAL. A clear trend of increasing rotational temperatures and linewidths with evolutionary stage is seen for source samples ranging from 24 micron dark clumps to clumps with embedded HII regions. The survey provides the largest ammonia sample of high-mass star forming clumps and thus presents an important repository for the characterization of statistical properties of the clumps and the selection of subsamples for detailed, high-resolution follow-up studies.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A72
- Title:
- A transiting rocky planet at 6.5pc from the Sun
- Short Name:
- J/A+A/584/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We know now from radial velocity surveys and transit space missions that planets only a few times more massive than our Earth are frequent around solar-type stars. Fundamental questions about their formation history, physical properties, internal structure, and atmosphere composition are, however, still to be solved. We present here the detection of a system of four low-mass planets around the bright (V=5.5) and close-by (6.5pc) star HD 219134. This is the first result of the Rocky Planet Search programme with HARPS-N on the Telescopio Nazionale Galileo in La Palma. The inner planet orbits the star in 3.0935+/-0.0003-days, on a quasi-circular orbit with a semi-major axis of 0.0382+/-0.0003AU. Spitzer observations allowed us to detect the transit of the planet in front of the star making HD 219134 b the nearest known transiting planet to date.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A104
- Title:
- Auriga bright stars BRITE phot. and RV
- Short Name:
- J/A+A/644/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine periods for bright stars in the Auriga field that are otherwise not easily accessible for ground-based photometry. Continuous photometry with up to three BRITE satellites was obtained for 12 targets and subjected to a period search. Contemporaneous high-resolution optical spectroscopy with STELLA was used to obtain radial velocities through cross correlation with template spectra as well as to determine astrophysical parameters through a comparison with model spectra.