- ID:
- ivo://CDS.VizieR/J/A+A/456/985
- Title:
- Radial velocities of 76 M31 candidate clusters
- Short Name:
- J/A+A/456/985
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a large spectroscopic survey of globular clusters and candidate globular clusters in the nearby M31 galaxy. The survey is aimed at the classification of known candidate M31 clusters and at the study of their kinematic properties. We obtained low-resolution spectroscopy for 133 targets, including 76 yet-to-be-confirmed candidate clusters (i.e. with no previous spectroscopic information), 55 already-confirmed genuine M31 clusters, and 2 uncertain candidates. Our observations allowed a reliable estimate of the target radial velocity, within a typical accuracy of ~+/-20Km/s. The observed candidates have been robustly classified according to their radial velocity and shape parameters that allowed us to confidently discriminate between point sources and extended objects even from low-spatial-resolution imagery. In our set of 76 candidate clusters we found: 42 newly-confirmed bona-fide M31 clusters, 12 background galaxies, 17 foreground Galactic stars, 2 HII regions belonging to M31 and 3 unclassified (possibly M31 clusters or foreground stars) objects. The classification of a few other candidates not included in our survey has been also reassessed on various observational bases. All the sources of radial velocity estimates for M31 known globular clusters available in the literature have been compared and checked, and a homogeneous general list has been obtained for 349 confirmed clusters with radial velocity. Our results suggest that a significant number of genuine clusters (~>100) is still hidden among the plethora of known candidates proposed by various authors. Hence our knowledge of the globular cluster system of the M31 galaxy is still far from complete even in terms of simple membership.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/813/89
- Title:
- Radial velocities of Milky Way inner halo stars
- Short Name:
- J/ApJ/813/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the three components of velocity dispersion, {sigma}_R_, {sigma}_{theta}_, {sigma}_{phi}_, for stars within 6<R<30kpc of the Milky Way using a new radial velocity sample from the MMT telescope. We combine our measurements with previously published data so that we can more finely sample the stellar halo. We use a maximum likelihood statistical method for estimating mean velocities, dispersions, and covariances assuming only that velocities are normally distributed. The alignment of the velocity ellipsoid is consistent with a spherically symmetric gravitational potential. From the spherical Jeans equation, the mass of the Milky Way is M(R<=12kpc)=1.3x10^11^M_{sun}_ with an uncertainty of 40%. We also find a region of discontinuity, 15<~R<~25kpc, where the estimated velocity dispersions and anisotropies diverge from their anticipated values, confirming the break observed by others. We argue that this break in anisotropy is physically explained by coherent stellar velocity structure in the halo, such as the Sgr stream. To significantly improve our understanding of halo kinematics will require combining radial velocities with future Gaia proper motions.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A22
- Title:
- Radial velocities of 3 new hot Jupiters
- Short Name:
- J/A+A/563/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-precision radial-velocity measurements of three solar-type stars: HD 13908, HD 159243, and HIP 91258. The observations were made with the SOPHIE spectrograph at the 1.93m telescope of the Observatoire de Haute-Provence (France). They show that these three bright stars host exoplanetary systems composed of at least two companions.
- ID:
- ivo://CDS.VizieR/J/AJ/136/506
- Title:
- Radial velocities of {omega} Centauri members
- Short Name:
- J/AJ/136/506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the two-degree field (2dF) multi-fiber spectrograph of the Anglo-Australian Telescope (AAT) to search for candidate members of the unusual globular cluster omega Centauri at and beyond the cluster tidal radius. Velocities with an accuracy of ~10km/s were obtained for 4105 stars selected to lie in the vicinity of the lower giant branch in the cluster color-magnitude diagram (CMD) and which cover an area on the sky of ~2.4x3.9{deg}^2^ centered on the cluster.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2183
- Title:
- Radial velocities of red giants in {omega} Cen
- Short Name:
- J/MNRAS/396/2183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a survey of radial velocities over a wide region extending from r~=10 out to 80' (~1.5 tidal radii) within the massive star cluster omega Centauri (omega Cen). The survey was performed with FLAMES@VLT, to study the velocity dispersion profile in the outer regions of this stellar system. We derived accurate radial velocities for a sample of 2557 newly observed stars, identifying 318 bona fide cluster red giants. Merging our data with those provided by our previous survey, we assembled a final homogeneous sample of 946 cluster members that allowed us to trace the velocity dispersion profile from the centre out to r~32'.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/146
- Title:
- Radial velocities of stars in Bootes I
- Short Name:
- J/ApJ/736/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop, implement, and characterize an enhanced data reduction approach which delivers precise, accurate, radial velocities from moderate resolution spectroscopy with the fiber-fed VLT/FLAMES+GIRAFFE facility. This facility, with appropriate care, delivers radial velocities adequate to resolve the intrinsic velocity dispersions of the very faint dwarf spheroidal (dSph) galaxies. Importantly, repeated measurements let us reliably calibrate our individual velocity errors (0.2km/s<={delta}_V_<=5km/s) and directly detect stars with variable radial velocities. We show, by application to the Bootes I dSph, that the intrinsic velocity dispersion of this system is significantly below 6.5km/s reported by previous studies. Our data favor a two-population model of Bootes I, consisting of a majority "cold" stellar component, with velocity dispersion 2.4^+0.9^_-0.5_km/s, and a minority "hot" stellar component, with velocity dispersion ~9km/s, although we cannot completely rule out a single component distribution with velocity dispersion 4.6^0.8^_-0.6_km/s. We speculate that this complex velocity distribution actually reflects the distribution of velocity anisotropy in Bootes I, which is a measure of its formation processes.
- ID:
- ivo://CDS.VizieR/J/ApJ/443/124
- Title:
- Radial Velocities of Stars in M4
- Short Name:
- J/ApJ/443/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The internal stellar velocity distribution of the globular cluster M4 is evaluated from nearly 200 new radial velocity measurements good to 1 km/s and a rederivation of existing proper motions. The mean radial velocity of the cluster is 70.9 +/- 0.6 km/s. The velocity dispersion is 3.5 +/- 0.3 km/s at the core, dropping marginally towards the outskirts. Such a low internal dispersion is somewhat at odds with the cluster's orbit, for which the perigalacticon is sufficiently close to the galactic center that the probability of cluster disruption is high; a tidal radius two-thirds the currently accepted value would eliminate the discrepancy. The cluster mass-to-light ratio is also small, M/L_V = 1.0 +/- 0.4 in solar units. M4 thus joins M22 as a cluster of moderate mass and concentration with a mass-to-light ratio among the lowest known. The astrometric distance to the cluster is also smaller than expected, 1.72 +/- 0.14 kpc. This is only consistent with conventional estimates of the luminosity of horizontal branch stars provided an extinction law R = A_V/E(B-V) ~ 4 is adopted, as has been suggested recently by several authors.
- ID:
- ivo://CDS.VizieR/J/AJ/149/119
- Title:
- Radial velocities of stars in NGC 2264
- Short Name:
- J/AJ/149/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an expanded kinematic study of the young cluster NGC 2264 based upon optical radial velocities measured using multi-fiber echelle spectroscopy at the 6.5m MMT and Magellan telescopes. We report radial velocities for 695 stars, of which approximately 407 stars are confirmed or very likely members. Our results more than double the number of members with radial velocities from Furesz et al., resulting in a much better defined kinematic relationship between the stellar population and the associated molecular gas. In particular, we find that there is a significant subset of stars that are systematically blueshifted with respect to the molecular (^13^CO) gas. The detection of Lithium absorption and/or infrared excesses in this blueshifted population suggests that at least some of these stars are cluster members; we suggest some speculative scenarios to explain their kinematics. Our results also more clearly define the redshifted population of stars in the northern end of the cluster; we suggest that the stellar and gas kinematics of this region are the result of a bubble driven by the wind from O7 star S Mon. Our results emphasize the complexity of the spatial and kinematic structure of NGC 2264, important for eventually building up a comprehensive picture of cluster formation.
- ID:
- ivo://CDS.VizieR/J/AJ/145/134
- Title:
- Radial velocities of 108 stars in Ruprecht 147
- Short Name:
- J/AJ/145/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ruprecht 147 is a hitherto unappreciated open cluster that holds great promise as a standard in fundamental stellar astrophysics. We have conducted a radial velocity survey of astrometric candidates with Lick, Palomar, and MMT observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H]=+0.07+/-0.03. We have obtained deep CFHT/MegaCam g'r'i'z' photometry and fit Padova isochrones to the (g'-i') and Two Micron All Sky Survey (J-K_S_) color-magnitude diagrams, using the {tau}^2^ maximum-likelihood procedure of Naylor, and an alternative method using two-dimensional cross-correlations developed in this work. We find best fits for Padova isochrones at age t=2.5+/-0.25Gyr, m-M=7.35+/-0.1, and A_V_=0.25+/-0.05, with additional uncertainty from the unresolved binary population and possibility of differential extinction across this large cluster. The inferred age is heavily dependent on our choice of stellar evolution model: fitting Dartmouth and PARSEC models yield age parameters of 3Gyr and 3.25Gyr, respectively. At ~300pc and ~3Gyr, Ruprecht 147 is by far the oldest nearby star cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/29
- Title:
- Radial velocities of TOI-1728 with HPF
- Short Name:
- J/ApJ/899/29
- Date:
- 14 Mar 2022 09:03:00
- Publisher:
- CDS
- Description:
- We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an old, inactive M0 star with Teff=3980_-32_^+31^K, which hosts a transiting super-Neptune at an orbital period of ~3.49days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of 5.05_-0.17_^+0.16^ R{Earth}, mass 26.78_-5.13_^+5.43^M{Earth}, and eccentricity 0.057_-0.039_^+0.054^. We estimate the stellar properties, and perform a search for He 10830{AA} absorption during the transit of this planet and claim a null detection with an upper limit of 1.1% with 90% confidence. A deeper level of He 10830{AA} absorption has been detected in the planet atmosphere of GJ3470b, a comparable gaseous planet. TOI-1728b is the largest super-Neptune-the intermediate subclass of planets between Neptune and the more massive gas-giant planets-discovered around an M-dwarf. With its relatively large mass and radius, TOI-1728 represents a valuable data point in the M-dwarf exoplanet mass-radius diagram, bridging the gap between the lighter Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. With a low bulk density of 1.14_-0.24_^+0.26^g/cm^3^, and orbiting a bright host star (J~9.6, V~12.4), TOI-1728b is also a promising candidate for transmission spectroscopy both from the ground and from space, which can be used to constrain planet formation and evolutionary models.
