- ID:
- ivo://CDS.VizieR/J/AJ/154/14
- Title:
- Low-mass stars in 25 Ori group and Orion OB1a
- Short Name:
- J/AJ/154/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Orion OB1a sub-association is a rich low-mass star (LMS) region. Previous spectroscopic studies have confirmed 160 LMSs in the 25 Orionis stellar group (25 Ori), which is the most prominent overdensity of Orion OB1a. Nonetheless, the current census of the 25 Ori members is estimated to be lower than 50% complete, leaving a large number of members to be still confirmed. We retrieved 172 low-resolution stellar spectra in Orion OB1a observed as ancillary science in the SDSS-III/BOSS survey, for which we classified their spectral types and determined physical parameters. To determine memberships, we analyzed the H{alpha} emission, LiI{lambda}6708 absorption, and NaI{lambda}{lambda}8183,8195 absorption as youth indicators in stars classified as M type. We report 50 new LMSs spread across the 25 Orionis, ASCC18, and ASCC20 stellar groups with spectral types from M0 to M6, corresponding to a mass range of 0.10{<=}m/M_{Sun}_{<=}0.58. This represents an increase of 50% in the number of known LMSs in the area and a net increase of 20% in the number of 25 Ori members in this mass range. Using parallax values from the Gaia DR1 catalog, we estimated the distances to these three stellar groups and found that they are all co-distant, at 338+/-66pc. We analyzed the spectral energy distributions of these LMSs and classified their disks into evolutionary classes. Using H-R diagrams, we found a suggestion that 25 Ori could be slightly older than the other two observed groups in Orion OB1a.
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112. Members of IC 2391
- ID:
- ivo://CDS.VizieR/J/A+AS/126/357
- Title:
- Members of IC 2391
- Short Name:
- J/A+AS/126/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New 4-colour BV(RI)_KC_ CCD photometry to a limiting magnitude of V=~19 is presented for 1428 objects observed towards the direction of the young, open cluster IC 2391. We observed 36 (2'x3') fields within 17arcmin of the nominal cluster core. By fitting the theoretical isochrones of D'Antona & Mazzitelli (1994ApJS...90..467D) to a combination of colour-magnitude and colour-colour diagrams, we have identified 17 stars as probable cluster members with a further 85 stars as possible members. The brightness distribution of low-mass members is compared with the luminosity function observed for the Pleiades and we estimate that the contamination due to background giants should be small.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/87
- Title:
- Members of the young open cluster IC 2395
- Short Name:
- J/ApJ/832/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new deep UBVRI images and high-resolution multi-object optical spectroscopy of the young (~6-10Myr old), relatively nearby (800pc) open cluster IC 2395. We identify nearly 300 cluster members and use the photometry to estimate their spectral types, which extend from early B to middle M. We also present an infrared imaging survey of the central region using the IRAC and MIPS instruments on board the Spitzer Space Telescope, covering the wavelength range from 3.6 to 24{mu}m. Our infrared observations allow us to detect dust in circumstellar disks originating over a typical range of radii from ~0.1 to ~10 au from the central star. We identify 18 Class II, 8 transitional disk, and 23 debris disk candidates, respectively, 6.5%, 2.9%, and 8.3% of the cluster members with appropriate data. We apply the same criteria for transitional disk identification to 19 other stellar clusters and associations spanning ages from ~1 to ~18Myr. We find that the number of disks in the transitional phase as a fraction of the total with strong 24{mu}m excesses ([8]-[24]>=1.5) increases from (8.4+/-1.3)% at ~3Myr to (46+/-5)% at ~10Myr. Alternative definitions of transitional disks will yield different percentages but should show the same trend.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A101
- Title:
- Milky Way global survey of star clusters. V.
- Short Name:
- J/A+A/585/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the integrated magnitudes of 3208 star clusters in the 2MASS near-infrared (JHKs) passbands.
- ID:
- ivo://CDS.VizieR/J/MNRAS/463/1831
- Title:
- M67 Kepler/K2 variable stars
- Short Name:
- J/MNRAS/463/1831
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the third paper of this series we continue the exploitation of Kepler/K2 data in dense stellar fields using our PSF-based method. This work is focused on a ~720-arcmin^2^ region centred on the Solar-metallicity and Solar-age open cluster M 67. We extracted light curves for all detectable sources in the Kepler channels 13 and 14, adopting our technique based on the usage of a high-angular-resolution input catalogue and target-neighbour subtraction. We detrended light curves for systematic errors, and searched for variables and exoplanets using several tools. We found 451 variables, of which 299 are new detection. Three planetary candidates were detected by our pipeline in this field. Raw and detrended light curves, catalogues, and K2 stacked images used in this work will be released to the community.
- ID:
- ivo://CDS.VizieR/J/AJ/151/49
- Title:
- M6 open cluster: star members properties
- Short Name:
- J/AJ/151/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the first abundance analysis of 44 late B-, A-, and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myr). Low- and medium-resolution spectra, covering the 4500-5840 {AA} wavelength range, were obtained using the FLAMES/GIRAFFE spectrograph attached to the ESO Very Large Telescopes. We determined the atmospheric parameters using calibrations of the Geneva photometry and by adjusting the H_{beta}_ profiles to synthetic ones. The abundances of up to 20 chemical elements, from helium to mercury, were derived for 19 late B, 16 A, and 9 F stars by iteratively adjusting synthetic spectra to the observations. We also derived a mean cluster metallicity of [Fe/H]=0.07+/-0.03 dex from the iron abundances of the F-type stars. We find that for most chemical elements, the normal late B- and A-type stars exhibit larger star-to-star abundance variations than the F-type stars probably because of the faster rotation of the B and A stars. The abundances of C, O, Mg, Si, and Sc appear to be anticorrelated with that of Fe, while the opposite holds for the abundances of Ca, Ti, Cr, Mn, Ni, Y, and Ba as expected if radiative diffusion is efficient in the envelopes of these stars. In the course of this analysis, we discovered five new peculiar stars: one mild Am, one Am, and one Fm star (HD 318091, CD-32 13109, GSC 07380-01211, CP1), one HgMn star (HD 318126, CP3), and one He-weak P-rich (HD 318101, CP4) star. We also discovered a new spectroscopic binary, most likely a SB2. We performed a detailed modeling of HD 318101, the new He-weak P-rich CP star, using the Montreal stellar evolution code XEVOL which self-consistently treats all particle transport processes. Although the overall abundance pattern of this star is properly reproduced, we find that detailed abundances (in particular the high P excess) resisted modeling attempts even when a range of turbulence profiles and mass-loss rates were considered. Solutions are proposed which are still under investigation.
- ID:
- ivo://CDS.VizieR/J/A+AS/121/223
- Title:
- Multiphotometry of NGC 6611
- Short Name:
- J/A+AS/121/223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the search of Herbig Ae/Be objects in the extremely young open cluster NGC 6611 we have selected a sample of 52 pre-main sequence candidates, discovered by Walker (1961ApJ...133..438W), Sagar & Joshi (1979Ap&SS..66....3S), Chini & Wargau (1990A&A...227..213C) and The et al. (1990A&AS...82..319T). We continue the approach of the last paper by studying each star individually with new and unpublished Walraven WULBV, Johnson/Cousins UBV(RI)_C_ and Johnson JHKLM photometric data as well as low resolution spectroscopy. For a description of the Walraven, UBVRI, IJHKLMN and RI Cousins photometric systems, see e.g. <GCPD/11>, <GCPD/08>, <GCPD/09> and <GCPD/54>
- ID:
- ivo://CDS.VizieR/J/ApJ/646/269
- Title:
- Multiwavelength analysis of NGC 2362
- Short Name:
- J/ApJ/646/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength analysis of the young open cluster NGC 2362; UBVRcIc CCD photometric observations, together with available data in the Chandra database, near-infrared data from the Two Micron All Sky Survey (2MASS), and recently published H{alpha} spectroscopy were used to get information about the evolutionary stage of the cluster and the main physical properties of its stellar content. Cluster membership is estimated for every individual star by means of zero-age main sequence (ZAMS) and isochrone fitting. The cluster is confirmed to host a rich population of pre-main-sequence (PMS) objects and to contain a large number of X-ray-emitting stars, which reach from the PMS members of GK spectral type up to the most luminous OB main-sequence (MS) members. The PMS cluster members show no significant age spread, and the comparison to both PMS and post-MS isochrones suggests an homogeneous age for all cluster members. The analysis allows us to assess the validity of currently used PMS evolutionary models and supports the suggestion of a well-defined positive correlation of the X-ray emission from PMS stars with their bolometric luminosity. Clear differences are found between the X-ray activity properties of MS and PMS cluster members, both in the relation between X-ray luminosity and bolometric luminosity, and in spectral properties as well.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1279
- Title:
- Multiwavelength study of NGC 7419
- Short Name:
- J/MNRAS/391/1279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new UBVRI H{alpha} CCD photometric observations and the archival infrared and X-ray data, we have carried out a multiwavelength study of a Perseus arm young open star cluster NGC 7419. Using XMM-Newton observations, we found several X-ray sources in the cluster region but none of the Herbig Ae/Be stars is detected in X-rays.
- ID:
- ivo://CDS.VizieR/J/PASJ/64/107
- Title:
- Multiwavelength study of NGC 281 complex
- Short Name:
- J/PASJ/64/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of the NGC 281 complex, which contains the young cluster IC 1590 at the center, using deep wide-field optical UBVIc photometry, slitless spectroscopy along with archival data sets in the near-infrared (NIR) and X-ray regions.