- 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.
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- ID:
- ivo://CDS.VizieR/J/A+A/633/A146
- Title:
- Radial velocities of stars in NGC 2546
- Short Name:
- J/A+A/633/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a broader project on the role of binary stars in clusters, we present a spectroscopic study of the open cluster NGC 2546, which is a large cluster lacking previous spectroscopic analysis. We report the finding of two open clusters in the region of NGC 2546. For the two star groups, we determine radial velocity, parallax, proper motion, reddening, distance modulus, and age, using our spectroscopic observations and available photometric and astrometric data, mainly from Gaia Data Release 2 (Gaia DR2). We also determine the orbit of four spectroscopic binaries in these open clusters. From mid-resolution spectroscopic observations for 28 stars in the NGC 2546 region, we determined radial velocities and evaluate velocity variability. To analyze double-lined spectroscopic binaries, we used a spectral separation technique and fit the spectroscopic orbits using a least-squares code. The presence of two stellar groups is suggested by the radial velocity distribution and confirmed by available photometric and astrometric data. We applied a multi-criteria analysis to determine cluster membership, and we obtained kinematic and physical parameters of the clusters. NGC 2546 is actually two clusters, NGC 2546A and NGC 2546B, the are not physically related to each other. NGC 2546A has an age of about 180Myr and a distance of 950pc. It has a half-number radius of 8pc and contains about 480 members brighter than G=18 mag. NGC 2546B is a very young cluster (<10Myr) located at a distance of 1450pc. It is a small cluster with 80 members and a half-number radius of 1.6pc. Stars less massive than 2.5 solar masses in this cluster would be pre- main-sequence objects. We detected four spectroscopic binaries and determined their orbits. The two binaries of NGC 2546A contain chemically peculiar components: HD 68693 is composed of two mercury- manganese stars and HD 68624 has a Bp silicon secondary. Among the most massive objects of NGC 2546B, there are two binary stars: HD 68572, with P=124.2d, and CD -37 4344 with P=10.4d.
- ID:
- ivo://CDS.VizieR/J/A+A/415/145
- Title:
- Radial velocities of 16 stars in NGC 6913
- Short Name:
- J/A+A/415/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1996 and 2003 we obtained 226 high resolution spectra of 16 stars in the field of the young open cluster NGC 6913, to constrain its main properties and study its internal kinematics. Twelve of the program stars turned out to be members, one of them probably unbound. Nine are binaries (one eclipsing and another double lined) and for seven of them the observations allowed us to derive the orbital elements. All but two of the nine discovered binaries are cluster members. In spite of the young age (a few Myr), the cluster already shows signs that could be interpreted as evidence of dynamical relaxation and mass segregation. However, they may be also the result of an unconventional formation scenario. The dynamical (virial) mass as estimated from the radial velocity dispersion is larger than the cluster luminous mass, which may be explained by a combination of the optically thick interstellar cloud that occults part of the cluster, the unbound state or undetected very wide binary orbit of some of the members that inflate the velocity dispersion and a high inclination for the axis of possible cluster angular momentum. All the discovered binaries are hard enough to survive average close encounters within the cluster and do not yet show signs of relaxation of the orbital elements to values typical of field binaries.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A4
- Title:
- Radial velocities of stars in NGC 2302 field
- Short Name:
- J/A+A/580/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spiral structure of the Milky Way (MW) is highly uncertain and is the subject of much discussion nowadays. Even the spiral structure close to the Sun and the real nature of the so-called Local or Orion arm are poorly known. We present the first result from a program that determines the properties of the Local (Orion) spiral arm (LOA), together with a full description of the program. In this context we have made a comprehensive study of the young LOA open cluster NGC 2302, which includes a UBVRI photometric analysis and determination of its kinematic properties - proper motion (PM) and radial velocity (RV) - and of its orbital parameters.
- 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/681/1254
- Title:
- Radial velocities of stars in the Galactic Center
- Short Name:
- J/ApJ/681/1254
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from K-band slit scan observations of a ~20"x20" region of the Galactic center (GC) in two separate epochs more than 5 years apart. The high-resolution (R={lamda}/{Delta}{lambda}>=14000) observations allow the most accurate radial velocity and acceleration measurements of the stars in the central parsec of the Galaxy. Detected stars can be divided into three groups based on the CO absorption band heads at ~2.2935um and the HeII lines at ~2.0581 and ~2.112, 2.113um: cool, narrow-line hot, and broad-line hot. The radial velocities of the cool, late-type stars have approximately a symmetrical distribution with its center at ~-7.8+/-10.3km/s and a standard deviation ~113.7+/-10.3km/s. Although our statistics are dominated by the brightest stars, we estimate a central black hole mass of (3.9+/-1.1)x10^6^M_{sun}_, consistent with current estimates from complete orbits of individual stars. Our surface density profile and the velocity dispersion of the late-type stars support the existence of a low-density region at the Galactic center suggested by earlier observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/675/201
- Title:
- Radial velocities of stars near Leo I
- Short Name:
- J/ApJ/675/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new kinematic results for 387 stars near the Milky Way satellite dwarf spheroidal galaxy Leo I. Spectra were obtained with the Hectochelle multiobject echelle spectrograph on the MMT, centered in the optical near 5200{AA}.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A139
- Title:
- Radial Velocities of stars observed in M67
- Short Name:
- J/A+A/545/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise stellar radial velocities are used to search for massive (Jupiter masses or higher) exoplanets around the stars of the open cluster M67. We observed a total of 88 main-sequence stars, subgiants, and giants all highly probable members of M67, using four telescopes and instrument combinations: the HARPS spectrograph at the ESO 3.6m, the SOPHIE spectrograph at OHP, the CORALIE spectrograph at the Euler Swiss telescope and the HRS spectrograph at Hobby Eberly Telescope. We investigate whether exoplanets are present by obtaining radial velocities with precisions as good as 10m/s.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A47
- Title:
- Radial velocities of 3 stars with giant planets
- Short Name:
- J/A+A/512/A47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of three new giant planets around three metal-deficient stars: HD5388b (1.96M_Jup_), HD181720b (0.37M_Jup_), and HD190984b (3.1M_Jup_). All the planets have moderately eccentric orbits (ranging from 0.26 to 0.57), and long orbital periods (from 777 to 4885 days). Two of the stars (HD181720 and HD190984) were part of a program searching for giant planets around a sample of ~100 moderately metal-poor stars, while HD5388 was part of the volume-limited sample of the HARPS GTO program. Our discoveries suggest that giant planets in long period orbits are not uncommon around moderately metal-poor stars. We present the results of a study of streaming motion of galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A145
- Title:
- Radial velocities of 8 stars with giant planets
- Short Name:
- J/A+A/588/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity measurements of eight stars that were secured with the spectrograph SOPHIE at the 193cm telescope of the Haute-Provence Observatory. The measurements allow detecting and characterizing new giant extrasolar planets. The host stars are dwarfs of spectral types between F5 and K0 and magnitudes of between 6.7 and 9.6; the planets have minimum masses M_p_sini of between 0.4 to 3.8M_Jup_ and orbitalperiods of several days to several months. The data allow only single planets to be discovered around the first six stars (HD 143105, HIP 109600, HD 35759, HIP 109384, HD 220842, and HD 12484), but one of them shows the signature of an additional substellar companion in the system. The seventh star, HIP 65407, allows the discovery of two giant planets that orbit just outside the 12:5 resonance in weak mutual interaction. The last star, HD 141399, was already known to host a four-planet system; our additional data and analyses allow new constraints to be set on it. We present Keplerian orbits of all systems, together with dynamical analyses of the two multi-planet systems. HD 143105 is one of the brightest stars known to host a hot Jupiter, which could allow numerous follow-up studies to be conducted even though this is not a transiting system. The giant planets HIP 109600b, HIP 109384b, and HD 141399c are located in the habitable zone of their host star.
