- ID:
- ivo://CDS.VizieR/J/A+A/620/A139
- Title:
- Planet candidates in open clusters
- Short Name:
- J/A+A/620/A139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detecting exoplanets in clusters of different ages is a powerful tool for understanding a number of open questions, such as how the occurrence rate of planets depends on stellar metallicity, on mass, or on stellar environment. We present the first results of our HARPS long-term radial velocity (RV) survey which aims to discover exoplanets around intermediate-mass (between ~2 and 6M_{sun}_) evolved stars in open clusters. We selected 826 bona fide HARPS observations of 114 giants from an initial list of 29 open clusters and computed the half-peak to peak variability of the HARPS RV measurements, namely {Delta}RV/2, for each target, to search for the best planet-host candidates. We also performed time series analyses for a few targets for which we have enough observations to search for orbital solutions. Although we attempted to rule out the presence of binaries on the basis of previous surveys, we detected 14 new binary candidates in our sample, most of them identified from a comparison between HARPS and CORAVEL data. We also suggest 11 new planet-host candidates based on a relation between the stellar surface gravity and {Delta}RV/2. Ten of the candidates are less than 3M_{sun}_, showing evidence of a low planet occurrence rate for massive stars. One of the planet-host candidates and one of the binary candidates show very clear RV periodic variations, allowing us to confirm the discovery of a new planet and to compute the orbital solution for the binary. The planet is IC 4651 9122b, with a minimum mass of msini=6.3M_J_ and a semimajor axis a=2.0AU. The binary companion is NGC 5822 201B, with a very low minimum mass of msini=0.11M_{sun}_ and a semimajor axis a=6.5AU, which is comparable to the Jupiter distance to the Sun.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/126/469
- Title:
- PolarBase catalogue of stellar spectra
- Short Name:
- J/PASP/126/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PolarBase is an evolving data base that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2,000 stellar objects throughout the Hertzsprung-Russell diagram are available. Intensity spectra are available for all targets, and the majority of the observations also include simultaneous spectra in circular or linear polarization, with the majority of the polarimetric measurements being performed only in circularly polarized light (Stokes V). Observations are associated with a cross-correlation pseudo-line profile in all available Stokes parameters, greatly increasing the detectability of weak polarized signatures. Stokes V signatures are detected for more than 300 stars of all masses and evolutionary stages, and linear polarization is detected in 35 targets. The detection rate in Stokes V is found to be anti-correlated with the stellar effective temperature. This unique set of Zeeman detections offers the first opportunity to run homogeneous magnetometry studies throughout the H-R diagram. The web interface of PolarBase is available at http://polarbase.irap.omp.eu.
- ID:
- ivo://CDS.VizieR/B/polarbase
- Title:
- PolarBase spectropolarimetric database (ESPaDOnS, NARVAL)
- Short Name:
- B/polarbase
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PolarBase is an evolving data base that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2,000 stellar objects throughout the Hertzsprung-Russell diagram are available. Intensity spectra are available for all targets, and the majority of the observations also include simultaneous spectra in circular or linear polarization, with the majority of the polarimetric measurements being performed only in circularly polarized light (Stokes V). Observations are associated with a cross-correlation pseudo-line profile in all available Stokes parameters, greatly increasing the detectability of weak polarized signatures. Stokes V signatures are detected for more than 300 stars of all masses and evolutionary stages, and linear polarization is detected in 35 targets. The detection rate in Stokes V is found to be anti-correlated with the stellar effective temperature. This unique set of Zeeman detections offers the first opportunity to run homogeneous magnetometry studies throughout the H-R diagram. The web interface of PolarBase is available at http://polarbase.irap.omp.eu.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/149
- Title:
- Polarized SiO masers of VX Sgr
- Short Name:
- J/ApJ/728/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Submillimeter Array observations of high-frequency SiO masers around the supergiant VX Sgr and the semi-regular variable star W Hya. The J=5-4, v=1^28^SiO and v=0^29^SiO masers of VX Sgr are shown to be highly linearly polarized with a polarization from ~5% to 60%. Assuming the continuum emission peaks at the stellar position, the masers are found within ~60mas of the star, corresponding to ~100AU at a distance of 1.57kpc. The linear polarization vectors are consistent with a large-scale magnetic field, with position and inclination angles similar to that of the dipole magnetic field inferred in the H_2_O and OH maser regions at much larger distances from the star. We thus show for the first time that the magnetic field structure in a circumstellar envelope can remain stable from a few stellar radii out to ~1400AU. This provides further evidence supporting the existence of large-scale and dynamically important magnetic fields around evolved stars. Due to a lack of parallactic angle coverage, the linear polarization of masers around W Hya could not be determined. For both stars, we observed the ^28^SiO and ^29^SiO isotopologues and find that they have a markedly different distributions and that they appear to avoid each other. Additionally, emission from the SO 5_5_-4_4_ line was imaged for both sources. Around W Hya, we find a clear offset between the red- and blueshifted SO emission. This indicates that W Hya is likely host to a slow bipolar outflow or a rotating disk-like structure.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/83
- Title:
- Praesepe members rotational periods from K2 LCs
- Short Name:
- J/ApJ/842/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze K2 light curves for 794 low-mass (1>~M_*_>~0.1M_{sun}_) members of the ~650Myr old open cluster Praesepe and measure rotation periods (P_rot_) for 677 of these stars. We find that half of the rapidly rotating >~0.3M_{sun}_ stars are confirmed or candidate binary systems. The remaining >~0.3M_{sun}_ fast rotators have not been searched for companions, and are therefore not confirmed single stars. We previously found that nearly all rapidly rotating 0.3M_{sun}_ stars in the Hyades are binaries, but we require deeper binary searches in Praesepe to confirm whether binaries in these two co-eval clusters have different P_rot_ distributions. We also compare the observed P_rot_ distribution in Praesepe to that predicted by models of angular-momentum evolution. We do not observe the clear bimodal P_rot_ distribution predicted by Brown (2014ApJ...789..101B) for >0.5M_{sun}_ stars at the age of Praesepe, but 0.25-0.5M_{sun}_ stars do show stronger bimodality. In addition, we find that >60% of early M dwarfs in Praesepe rotate more slowly than predicted at 650Myr by Matt+ (2015ApJ...799L..23M), which suggests an increase in braking efficiency for these stars relative to solar-type stars and fully convective stars. The incompleteness of surveys for binaries in open clusters likely impacts our comparison with these models since the models only attempt to describe the evolution of isolated single stars.
- ID:
- ivo://CDS.VizieR/J/AJ/121/2148
- Title:
- Precise spectral types for 372 A, F & G stars
- Short Name:
- J/AJ/121/2148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of two papers that address the problem of the physical nature of luminosity classification in the late A-, F-, and early G-type stars. In this paper, we present precise spectral classifications of 372 stars on the MK system. For those stars in the set with Stroemgren uvby{beta} photometry, we derive reddenings and present a calibration of MK temperature types in terms of the intrinsic Stroemgren (b-y)_0_ index. We also examine the relationship between the luminosity class and the Stroemgren c_1_ index, which measures the Balmer jump. The second paper will address the derivation of the physical parameters of these stars, and the relationships between these physical parameters and the luminosity class. Stars classified in this paper include one new {lambda} Bootis star and 10 of the F- and G-type dwarfs with recently discovered planets.
- ID:
- ivo://CDS.VizieR/J/ApJS/152/103
- Title:
- Proper-motion catalog SDSS + USNO-B
- Short Name:
- J/ApJS/152/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of ~390000 stars with proper motions {mu}>=20mas/yr and magnitudes r'<=20, drawn from the intersection of the SDSS Data Release One (see http://www.sdss.org/dr1) and USNO-B (<I/284>). We first use SDSS quasars to correct the proper motions in each of the two source catalogs, finding that these corrections for systematics are comparable to the statistical errors. The combined proper motions have errors of {sigma}{mu}=3.9mas/yr, significantly better than any previous catalog at these magnitudes. While cross-correlating SDSS and USNO-B removes the vast majority of the very large number of spurious proper-motion stars in each, some contamination remains, especially at faint magnitudes, r'>~19.5, and high proper motions. We present a diagrammatic method to estimate the level of contamination in selected subsets of the catalog, which should be useful for choosing appropriate selection criteria for various applications.
- ID:
- ivo://CDS.VizieR/J/A+A/341/L79
- Title:
- Proper motions of faint ROSAT WTT stars
- Short Name:
- J/A+A/341/L79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present proper motions of 59 stars of the ROSAT All-Sky Survey (RASS) located in direction of the Chamaeleon star forming region (SFR) in the magnitude range B=5.1-17mag. Proper motions of the fainter stars were newly derived utilizing survey Schmidt plates from the GSC~II plate archive and from a set of special plates taken with the ESO Schmidt telescope. The vector point diagram (VPD) indicates that the certified weak emission-line T Tauri (WTT) stars cluster away from the region occupied by the brighter pre-main-sequence stars (PMS) in Cha I. The distance to this new association is estimated at ~100pc, sensibly smaller than the 150pc generally assumed for the SFR. This yields an upper limit of 2km/s for the velocity dispersion of this new kinematic group. The de-reddened CM diagram of the group members suggest the WTT stars are still PMS objects, but older (3-30Myr) and less massive than previous determinations. These revised age estimates, the newly derived group peculiar velocity, and current distance estimates to the Cha~I/II/III complex would favour in-situ formation against that predicted by high velocity cloud models. Finally, based on a redetermination of the peculiar motions of stars and gas, we speculate that the whole SFR originated from the local Orion spur as a result of more classical mechanisms like interactions with the spiral arms.
- ID:
- ivo://CDS.VizieR/I/14
- Title:
- Proper Motions of 1160 Late-Type Stars
- Short Name:
- I/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Improved proper motions for the 1160 stars contained in the photometric catalog by Dickow et al. (1970A&AS....2....1D, II/38) are presented. Most of the proper motions are from the GC, transferred to the system of FK4. For stars not included in the GC, preliminary AGK or SAO proper motions are given. Olsen (1970A&AS....1..189O) describes the method of improvement. The mean errors of the centennial proper motions increase with increasing magnitude. In Right Ascension, these range from 0.0043/cos(dec) for very bright stars to 0.096/cos(dec) s for the faintest stars. In Declination, the range is from 0.065 to 1.14 arcsec.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A144
- Title:
- Proper motions of young stars in Chamaeleon
- Short Name:
- J/A+A/556/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for new candidate members of the Chamaeleon I and II star forming regions based on proper motions and multiwavelength photometry. Kinematic candidate members are initially selected in an area of 3 degrees around each cloud on the basis of proper motions and colours using the UCAC4 catalogue. The SEDs of the objects are constructed using photometry retrieved from the Virtual Observatory and other resources, and fitted to models of stellar photospheres in order to derive effective temperatures, gravity values and luminosities. Masses and ages are estimated by comparison with theoretical evolutionary tracks in a Hertzprung-Russell diagram. Objects with ages <=20Myr are selected as probable members of the moving groups. The properties of our candidates are compared with those of the previously known members of the clouds.
