- ID:
- ivo://CDS.VizieR/J/A+A/657/A7
- Title:
- Stellar and substellar companions from Gaia EDR3
- Short Name:
- J/A+A/657/A7
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The multiplicity fraction of stars, down to the substellar regime, is a parameter of fundamental importance for stellar formation, evolution, and planetology. The census of multiple stars in the solar neighborhood is however incomplete. The presence of a companion in orbit around a star affects its proper motion. We aim at detecting companions of Hipparcos catalog stars from the proper motion anomaly (PMa) they induce on their host star, that is, the difference between their long-term Hipparcos-Gaia and short-term Gaia proper motion vectors. We also aim at detecting resolved, gravitationally bound companions of the Hipparcos catalog stars (117955 stars), and of the Gaia EDR3 stars closer than 100 c (542232 stars). Using the Hipparcos and EDR3 data, we revise the PMa catalog for the Hipparcos stars. To identify gravitationally bound visual companions of our sample, we search the Gaia EDR3 catalog for common proper motion (CPM) candidates. The detection of tangential velocity anomalies with a median accuracy of 26cm/s per parsec of distance is demonstrated with the EDR3. This improvement by a factor 2.5 in accuracy compared to the Gaia DR2 results in PMa detection limits on companions well into the planetary mass regime for many targets. We identify 37515 Hipparcos stars presenting a PMa at significant level (S/N>3), that is, a fraction of 32% (compared to 30% for the DR2) and 12914 (11%) hosting CPM bound candidate companions. Including the Gaia EDR3 RUWE>1.4 as an additional indicator, 50,720 stars of the Hipparcos catalog (43%) exhibit at least one signal of binarity. Among the Gaia EDR3 stars located within 100 pc, we find CPM bound candidate companions for 39,490 stars (7.3% of the sample). The search for companions using a combination of the PMa, CPM and RUWE indicators significantly improves the exhaustivity of the multiplicity survey. The detection of CPM companions of very bright stars (heavily saturated on the Gaia detectors) that are classical benchmark objects for stellar physics provides a useful proxy to estimate their distance with a higher accuracy than Hipparcos.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/862/106
- Title:
- Stellar and substellar members in Coma Berenices
- Short Name:
- J/ApJ/862/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified stellar and substellar members in the nearby star cluster Coma Berenices, using photometry, proper motions, and distances of a combination of 2MASS, UKIDSS, URAT1, and Gaia/DR2 data. Those with Gaia/DR2 parallax measurements provide the most reliable sample to constrain the distance, averaging 86.7pc with a dispersion of 7.1pc, and age of ~800Myr, of the cluster. This age is older than the 400-600 Myr commonly adopted in the literature. Our analysis, complete within 5{deg} of the cluster radius, leads to identification of 192 candidates, among which, after field contamination is considered, about 148 are true members. The members have J~3mag to ~17.5mag, corresponding to stellar masses 2.3-0.06M_{sun}_. The mass function of the cluster peaks around 0.3M_{sun},_ and in the sense of dN/dm=m^-{alpha}^, where N is the number of members and m is stellar mass, with a slope {alpha}~=0.49+/-0.03 in the mass range 0.3-2.3M_{sun}_. This is much shallower than that of the field population in the solar neighborhood. The slope {alpha}=-1.69+/-0.14 from 0.3M_{sun}_ to 0.06M_{sun}_, the lowest mass in our sample. The cluster is mass-segregated and has a shape elongated toward the Galactic plane. Our list contains nine substellar members, including three new discoveries of an M8, an L1, and an L4 brown dwarfs, extending from the previously known coolest members of late-M types to even cooler types.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/4711
- Title:
- Stellar angular momentum for ManGa galaxies
- Short Name:
- J/MNRAS/477/4711
- Date:
- 17 Jan 2022 00:26:35
- Publisher:
- CDS
- Description:
- We measure {lambda}_Re_, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, {epsilon}, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the Mapping Nearby Galaxies at Apache Point Observatory survey, the largest such sample to date. We use the ({lambda}_Re_, {epsilon}) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative {lambda}_Re_ measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for {lambda}_Re_. Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the ({lambda}_Re_, {epsilon}) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low {lambda}_Re_ and {epsilon}<0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at +/-90{deg} in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above M>=2x10^11^M_{sun}_ where a significant number of high-mass fast rotators also exist.
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/538
- Title:
- Stellar association around gamma Vel
- Short Name:
- J/MNRAS/393/538
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric BVI survey of 0.9deg^2^ around the Wolf-Rayet binary gamma^2^ Vel and its early-type common proper motion companion gamma^1^ Vel (together referred to as the gamma Vel system). Several hundred pre-main-sequence (PMS) stars are identified and the youth of a subset of these is spectroscopically confirmed by the presence of lithium in their atmospheres, Halpha emission and high levels of X-ray activity. We show that the PMS stars are kinematically coherent and spatially concentrated around gamma Vel. The PMS stars have similar proper motions to gamma Vel, to main-sequence (MS) stars around gamma Vel and to early-type stars of the wider Vela OB2 association of which gamma^2^ Vel is the brightest member.
17945. Stellar associations in M51
- ID:
- ivo://CDS.VizieR/J/AJ/140/379
- Title:
- Stellar associations in M51
- Short Name:
- J/AJ/140/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data acquired as part of a unique Hubble Heritage imaging program of broadband colors of the interacting spiral system M51/NGC5195, we have conducted a photometric study of the stellar associations across the entire disk of the galaxy in order to assess trends in size, luminosity, and local environment associated with the recent star formation (SF) activity in the system. Starting with a sample of over 900 potential associations, we have produced color-magnitude and color-color diagrams for the 120 associations that were deemed to be single-aged.
- ID:
- ivo://CDS.VizieR/J/MNRAS/374/664
- Title:
- Stellar atmospheric parameters in MILES library
- Short Name:
- J/MNRAS/374/664
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a homogeneous set of stellar atmospheric parameters (Teff, logg, [Fe/H]) for MILES, a new spectral stellar library covering the range {lambda}{lambda}3525-7500{AA} at 2.3{AA} (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-metal-rich, cool stars to hot, metal-poor stars. The spectral resolution, spectral type coverage and number of stars represent a substantial improvement over previous libraries used in population synthesis models. The atmospheric parameters that we present here are the result of a previous, extensive compilation from the literature. In order to construct a homogeneous data set of atmospheric parameters we have taken the sample of stars of Soubiran, Katz & Cayrel (1998, Cat. <J/A+AS/133/221>, which has very well determined fundamental parameters, as the standard reference system for our field stars, and have calibrated and bootstrapped the data from other papers against it. The atmospheric parameters for our cluster stars have also been revised and updated according to recent metallicity scales, colour-temperature relations and improved set of isochrones.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/29
- Title:
- Stellar bow shock nebulae spectroscopic obs.
- Short Name:
- J/ApJS/251/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arcuate mid-infrared nebulae known as stellar bow shock nebulae (SBNe) have been previously hypothesized to be supported by the strong stellar winds and/or luminosity of massive early-type stars. We present an optical spectroscopic survey of 84 stars identified from mid-infrared images as candidate SBN-supporting stars. Eighty-one of 84 sources, 96%, are O or early-B spectral types. K-band luminosities for a larger sample of 289 stars at the centers of bow shock nebulae are overwhelmingly consistent with OB stars. This affirms both that SBNe are supported by massive stars and that arcuate mid-infrared nebulae are reliable indicators of the presence of a massive star. The radial velocity dispersions of these systems and detections of double-lined systems indicate that at least 27 of the 74 systems with multiple observations (>36%) are candidate multiple-star systems. This rate is consistent with observed multiplicity rates of field OB stars detected with similar radial velocity surveys and lower than, but not inconsistent with, the multiplicity rates of OB stars in clusters and associations.
- ID:
- ivo://CDS.VizieR/J/A+A/392/741
- Title:
- Stellar Catalogue in the Chandra DFS
- Short Name:
- J/A+A/392/741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar catalogues in five passbands (UBVRI) over an area of approximately 0.3{deg}^2^, comprising about 1200 objects, and in seven passbands (UBVRIJK) over approximately 0.1{deg}^2^, comprising about 400 objects, in the direction of the Chandra Deep Field South are presented. The 90% completeness level of the number counts is reached at approximately U=23.8, B=24.0, V=23.5, R=23.0, I=21.0, J=20.5, K=19.0. These multi-band catalogues have been produced from publicly available, single passband catalogues. A scheme is presented to select point sources from these catalogues, by combining the SExtractor parameter CLASS_STAR from all available passbands. Probable QSOs and unresolved galaxies are identified by using the previously developed {chi}^2^-technique (Hatziminaoglou et al., 2002, Cat. <J/A+A/384/81>), that fits the overall spectral energy distributions to template spectra and determines the best fitting template. Approximately 15% of true galaxies are misclassified as stars by the {chi}^2^ method. The number of unresolved galaxies and QSOs identified by the {chi}^2^-technique, allows us to estimate that the remaining level of contamination by such objects is at the level of 2.4% of the number of stars. The fraction of missing stars being incorrectly removed as QSOs or unresolved galaxies is estimated to be similar. The resulting stellar catalogues and the objects identified as likely QSOs and unresolved galaxies with coordinates, observed magnitudes with errors and assigned spectral types by the {chi}^2^-technique are presented and are publicly available.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A12
- Title:
- Stellar CharactEristics Pisa Estimation gRid
- Short Name:
- J/A+A/575/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar age determination by means of grid-based techniques that adopt asteroseismic constraints is a well established method nowadays. However some theoretical aspects of the systematic and statistical errors affecting these age estimates still have to be investigated. We study the impact on stellar age determination of the uncertainty in the radiative opacity, in the initial helium abundance, in the mixing-length value, in the convective core overshooting, and in the microscopic diffusion efficiency adopted in stellar model computations. We extended our SCEPtER grid to include stars with mass in the range [0.8; 1.6]M_{sun}_ and evolutionary stages from the zero-age main sequence to the central hydrogen depletion. For the age estimation we adopted the same maximum likelihood technique as described in our previous work. To quantify the systematic errors arising from the current uncertainty in model computations, many synthetic grids of stellar models with perturbed input were adopted. We found that the current typical uncertainty in the observations accounts for 1{sigma} statistical relative error in age determination, which on average ranges from about -35% to +42%, depending on the mass. However, owing to the strong dependence on the evolutionary phase, the age's relative error can be higher than 120% for stars near the zero-age main sequence, while it is typically of the order of 20% or lower in the advanced main-sequence phase. The systematic bias on age determination due to a variation of +/-1 in the helium-to-metal enrichment ratio {Delta}Y/{Delta}Z is about one-fourth of the statistical error in the first 30% of the evolution, while it is negligible for more evolved stages. The maximum bias due to the presence of the convective core overshooting is -7% and -13% for mild and strong overshooting scenarios. For all the examined models, the impact of a variation of +/-5% in the radiative opacity was found to be negligible. The most important source of bias is the uncertainty in the mixing-length value {alpha}_ml_ and the neglect of microscopic diffusion. Each of these effects accounts for a bias that is nearly equal to the random error uncertainty. Comparison of the results of our technique with other grid techniques on a set of common stars showed general agreement. However, the adoption of a different grid can account for a variation in the mean estimated age up to 1Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/1005
- Title:
- Stellar cluster dynamical masses in NGC3310
- Short Name:
- J/MNRAS/402/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 3310 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet in the near-IR, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H{beta} {lambda}4861{AA} and [OIII] {lambda}5007{AA} emission lines.