- ID:
- ivo://CDS.VizieR/J/A+A/624/A8
- Title:
- Evolved Galactic open clusters dynamical properties
- Short Name:
- J/A+A/624/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar content of Galactic open clusters (OCs) is gradually depleted during their evolution as a result of internal relaxation and external interactions. The final residues of the long-term evolution of OCs are called open cluster remnants (OCRs).These are sparsely populated structures that can barely be distinguished from the field. We aimed to characterise and compare the dynamical states of a set of 16 objects catalogued as OCRs or OCR candidates. The sample also includes 7 objects that are catalogued as dynamically evolved OCs for comparison purposes. We used photometric data from the 2MASS catalogue, proper motions and parallaxes from the GAIA DR2 catalogue, and a decontamination algorithm that was applied to the three-dimensional astrometric space of proper motions and parallaxes ({mu}_{alpha}, {mu}_{delta}, {varpi}) for stars in the objects' areas. The investigated OCRs present masses (M) and velocity dispersions ({sigma}_v_) within well-defined ranges: M between ~10-40M_{sun} and {sigma}_v_ between ~1-7km/s. Some objects in the remnant sample have a limiting radius R_lim_<~2pc, which means that they are more compact than the investigated OCs; other remnants have R_lim_ between ~2-7pc, which is comparable to the OCs. In general, our clusters show signals of depletion of low-mass stars. This confirms their dynamically evolved states. Using results from N-body simulations, we conclude that the OCRs we studied are in fact remnants of initially very populous OCs (N_0_~10^3^-10^4^stars). The outcome of the long-term evolution is to bring the final residues of the OCs to dynamical states that are similar to each other, thus masking out the memory of the initial formation conditions of star clusters.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/902/24
- Title:
- Evolved massive stars with TESS. II.
- Short Name:
- J/ApJ/902/24
- Date:
- 14 Mar 2022 07:45:17
- Publisher:
- CDS
- Description:
- Massive stars briefly pass through the yellow supergiant (YSG) phase as they evolve redward across the H-R diagram and expand into red supergiants (RSGs). Higher-mass stars pass through the YSG phase again as they evolve blueward after experiencing significant RSG mass loss. These post-RSG objects offer us a tantalizing glimpse into which stars end their lives as RSGs and why. One telltale sign of a post-RSG object may be an instability to pulsations, depending on the star's interior structure. Here we report the discovery of five YSGs with pulsation periods faster than 1 day, found in a sample of 76 cool supergiants observed by the Transiting Exoplanet Survey Satellite (TESS) at a two-minute cadence. These pulsating YSGs are concentrated in an H-R diagram region not previously associated with pulsations; we conclude that this is a genuine new class of pulsating star, fast yellow pulsating supergiants (FYPSs). For each FYPS, we extract frequencies via iterative prewhitening and conduct a time-frequency analysis. One FYPS has an extracted frequency that is split into a triplet, and the amplitude of that peak is modulated on the same timescale as the frequency spacing of the triplet; neither rotation nor binary effects are likely culprits. We discuss the evolutionary status of FYPS and conclude that they are candidate post-RSGs. All stars in our sample also show the same stochastic low-frequency variability found in hot OB stars and attributed to internal gravity waves. Finally, we find four {alpha} Cygni variables in our sample, of which three are newly discovered.
- ID:
- ivo://CDS.VizieR/J/MNRAS/498/5720
- Title:
- Extended Breakthrough Listen sample
- Short Name:
- J/MNRAS/498/5720
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We extend the source sample recently observed by the Breakthrough Listen Initiative by including additional stars (with parallaxes measured by Gaia) that also reside within the FWHM of the GBT and Parkes radio telescope target fields. These stars have estimated distances as listed in the extensions of the Gaia DR2 catalogue. Enlarging the sample from 1327 to 288315 stellar objects permits us to achieve substantially better Continuous Waveform Transmitter Rate Figures of Merit (CWTFM) than any previous analysis, and allows us to place the tightest limits yet on the prevalence of nearby high-duty-cycle extraterrestrial transmitters. The results suggest <~0.0660(+0.0004,-0.0003)% of stellar systems within 50 pc host such transmitters (assuming an EIRP>~10^13^W) and <~0.039(+0.004,-0.008)% within 200pc (assuming an EIRP>~2.5*10^14^W). We further extend our analysis to much greater distances, though we caution that the detection of narrow-band signals beyond a few hundred pc may be affected by interstellar scintillation. The extended sample also permits us to place new constraints on the prevalence of extraterrestrial transmitters by stellar type and spectral class. Our results suggest targeted analyses of SETI radio data can benefit from taking into account the fact that in addition to the target at the field centre, many other cosmic objects reside within the primary beam response of a parabolic radio telescope. These include foreground and background galactic stars, but also extragalactic systems. With distances measured by Gaia, these additional sources can be used to place improved limits on the prevalence of extraterrestrial transmitters, and extend the analysis to a wide range of cosmic objects.
- ID:
- ivo://CDS.VizieR/V/137D
- Title:
- Extended Hipparcos Compilation (XHIP)
- Short Name:
- V/137D
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Extended Hipparcos Compilation (XHIP) cross-references the New Hipparcos Reduction (HIP2, Cat. I/311) with relatable data from a broad survey of presently available sources. The resulting collection uniquely assigns 116,096 spectral classifications, 46,392 radial velocities, and 19,097 iron abundances [Fe/H] to Hipparcos stars. Stellar classifications from SIMBAD and indications of multiplicity from either CCDM (Cat. I/274) or WDS (Cat. B/wds) are provided. Parameters for solar encounters and Galactic orbits are calculated for a subset of stars that can be made kinematically complete. Memberships in open clusters and stellar associations are assigned. We also provide stellar ages from The Geneva-Copenhagen survey of the Solar neighbourhood III (Cat. V/130), identifications of exoplanet host stars, and supplemental photometry from 2MASS (Cat. II/246) and SIMBAD.
- ID:
- ivo://CDS.VizieR/J/A+A/409/361
- Title:
- Extension of ICRF for selected areas down to V=16
- Short Name:
- J/A+A/409/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of accurate positions and proper motions for 678,828 objects is provided. Objects are within areas of special astronomical interest, containing extragalactic radio sources, mostly from ICRF (see Cat. <I/251>), and pre-main-sequence (PMS) stars in Southern star-forming regions (Chamaeleon, Lupus and Upper Scorpius-Ophiuchus). This work represents a major upgrade of that presented in Camargo et al., 2001, Cat. <J/A+A/375/308>, aiming at the extension of the ICRF at optical wavelengths in regions of special astronomical interest, using observations from the Bordeaux and Valinhos meridian circles. Along with the new fields, the main differences, when compared to the first release, are: a much larger sky coverage, the replacement of the AC2000 by its upgraded version AC2000.2 (<I/275>) as one of the first epoch astrometrical sources, inclusion of Tycho-2 (<I/259>) and 2MASS (2nd Incremental Data Release, See Cat <II/246>) photometry when available, and the correction for a magnitude equation on the Valinhos right ascension system as well. Positional external precisions, on both coordinates, range from 50-60mas (V<=13.5) to 70-140mas (13.5<V<=16.0). For the proper motions, precisions range from 3mas/year to about 15mas/year, depending on magnitude and declination. The strips scanned by the meridian circles are described in Table 1
- ID:
- ivo://CDS.VizieR/J/A+A/375/308
- Title:
- Extension of ICRF for selected areas down to V=15
- Short Name:
- J/A+A/375/308
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of accurate positions and proper motions for 41,721 objects is provided. Objects are within areas of special astronomical interest, containing extragalactic radio sources, mostly from ICRF (see Cat. I/251), and pre-main-sequence (PMS) stars in Southern star-forming regions (Chamaeleon, Lupus and Upper Scorpius-Ophiuchus). Positions and proper motions were derived by combining current epoch positions, obtained with the Valinhos CCD meridian circle (VMC, see 1999A&AS..134..173V), with first epoch catalogues, AC2000 (I/247) and USNO-A2.0 (I/252) mainly, as well as positions from plate measurements performed with the MAMA measuring machine (Guibert J., Charvin P. & Stoclet P., 1983, in Proceedings of the 78th Colloquium of the IAU), in Paris. On average, objects with V<=14.0 have positional precisions better than 50mas in both coordinates, and 100mas near the detection limit of the VMC (V~16,0). For proper motions, average precisions are better than 4mas/year, whatever the magnitude, when delta>=-17{deg}. To the south of this declination, a magnitude dependence is verified due to a particular feature of the USNO-A2.0's epochs, providing figures of 3mas/year when V<=12.0, where the participation of AC2000 is noted, and reaching 17mas/year at the detection limit. The catalogue data is grouped by area, following the same order and identification as given in table 2 of the paper; within each area, objects are sorted by right ascension. The respective record numbers for the beginning of each area are provided in a separate table.
- ID:
- ivo://CDS.VizieR/J/AJ/133/889
- Title:
- Faint companions of Hipparcos stars
- Short Name:
- J/AJ/133/889
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a search for faint, common proper motion companions of Hipparcos stars using the recently published Lepine-Shara Prope-Motion-North catalog of stars with proper motion {mu}>0.15"/yr. Our survey uncovers a total of 521 systems with angular separations 3"<{Delta}{theta}<1500", with 15 triples and 1 quadruple. Our new list of wide systems with Hipparcos primaries includes 130 systems identified here for the first time, including 44 in which the secondary star has V>15.0. Our census is statistically complete for secondaries with angular separations 20"<{Delta}{theta}<300" and apparent magnitudes V<19.0. Overall, we find that at least 9.5% of nearby (d<100pc) Hipparcos stars have distant stellar companions with projected orbital separations s>1000AU.
- ID:
- ivo://CDS.VizieR/J/MNRAS/332/441
- Title:
- FAUST UV sources towards Ophiuchus
- Short Name:
- J/MNRAS/332/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour-colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars. Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos/Tycho (<I/239>) information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples.
- ID:
- ivo://CDS.VizieR/I/175
- Title:
- Fifth Fundamental Catalogue (FK5) - Extension
- Short Name:
- I/175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The FK5 Extension provides improved mean positions and proper motions for the 3117 new fundamental stars. The machine version of the catalog contains the positions and proper motions of the Extension stars for the epochs and equinoxes J2000.0 and B1950.0, the mean epochs of individual observed right ascensions and declinations used to determine the final positions, the mean errors of the final positions and proper motions for the reported epochs, and ancillary data such as magnitudes, spectral types, parallaxes, and radial velocities. Cross identifications to the numbering systems of the AGK3R, SRS, HD, DM, and GC catalogs are also included.
- ID:
- ivo://CDS.VizieR/I/149A
- Title:
- Fifth Fundamental Catalogue (FK5) Part I
- Short Name:
- I/149A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Basic Fifth Fundamental Catalogue (FK5) Part I provides improved mean positions and proper motions for the 1535 classical fundamental stars that had been included in the FK3 and FK4 catalogs. The machine version of the catalog contains the positions and proper motions of the Basic FK5 stars for the epochs and equinoxes J2000.0 and B1950.0, the mean epochs of individual observed right ascensions and declinations used to determine the final positions, the mean errors of the final positions and proper motions for the reported epochs, and ancillary data such as magnitudes, spectral types, parallaxes, radial velocities, and cross identifications to other catalog designations.