- ID:
- ivo://CDS.VizieR/J/AJ/124/404
- Title:
- Upper Scorpius OB association Lithium survey. II.
- Short Name:
- J/AJ/124/404
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the stellar population and star formation history of the Upper Scorpius OB association, the most nearby region of recent massive star formation, over the full stellar mass range from 0.1 to 20M_{sun}_. The first part of this paper describes an extension of our large spectroscopic survey (Preibisch et al., published in 2001, Cat. <J/AJ/121/1040>) for low-mass pre-main-sequence (PMS) stars in Upper Scorpius. Using the multiobject spectrograph 2dF at the Anglo-Australian Telescope, we obtained spectra of 469 stars with magnitudes R=12.5-18.0 in a 6{deg}^2^ area, on he nights of 2001 May 16-17. Among these, we find 68 new PMS stars, nearly all of them M-type stars, by their strong lithium absorption lines. The total area covered by our 2dF survey is now 9 deg2 and contains 166 new PMS stars. Combining these results with our earlier investigation (Preibisch & Zinnecker, 1999AJ....117.2381P) yields a sample of 250 PMS stars in the mass range ~0.2 to ~2M_{sun}_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/104/557
- Title:
- uvby-beta photometry in star-forming regions
- Short Name:
- J/A+AS/104/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/AJ/139/1338
- Title:
- UV-selected stars in Tau and Upper Sco
- Short Name:
- J/AJ/139/1338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56deg^2^ near the Taurus T association and 12deg^2^ along the northern edge of the Upper Scorpius OB association. We combined photometry in the GALEX far-ultraviolet and near-ultraviolet bands with data from the Two Micron All Sky Survey to identify candidate young (<~100Myr old) stars as those with an ultraviolet excess relative to older main-sequence stars. Follow-up spectroscopy of a partial sample of these candidates suggests five new members of Taurus, with 8-20 expected from additional observations, and five new members of Upper Scorpius, with three to six expected from additional observations.
- ID:
- ivo://CDS.VizieR/J/A+A/461/183
- Title:
- Variability of classical T Tauri
- Short Name:
- J/A+A/461/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a study the long term variability of Classical T Tauri stars (CTTS) over up to 20 years, characterize it from a set of statistical parameters and discuss its origin. We characterize the long term photometric variations of 49 CTTs with sufficient data for allowing a robust statistical analysis and propose an empirical classification scheme. Several patterns of long term photometric variability are identified. The most common pattern, exhibited by a group of 15 stars which includes T Tau itself, consists of low level variability (with V-amplitude less than 0.4mag) with no significant changes occurring from season to season over many years. A related subgroup of 22 stars exhibit a similar stable long term variability pattern, though with larger amplitudes (up to 1.6mag). Besides these representative groups, we identify three smaller groups of 3-5 stars each of which have distinctive photometric properties. The long term variability of most CTTS is fairly stable and merely reflects shorter term variability due to cold and hot surface spots. Only a small fraction of CTTS undergo significant brightness changes on the long term (months, years), which probably arise from slowly varying circumstellar extinction.
- ID:
- ivo://CDS.VizieR/J/MNRAS/487/3505
- Title:
- Variable stars in NGC 2244
- Short Name:
- J/MNRAS/487/3505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the UBVIc variability search for variable stars in the young open cluster NGC 2244. In total, we found 245 variable stars. Most of them, are pre-main sequence variables with irregular variations typical for classical T Tauri stars (CTTSs). We found also 23 periodic variables, probably weak-lined T Tauri stars (WTTSs). We detected also four candidates for {delta} Scuti stars and 7 eclipsing binaries. Based on the mid-infrared Spitzer and WISE photometry and near infrared JHKS 2MASS photometry, we classified 104 young stellar sources among our variables: 1 Class I object, 1 Class I/flat spectrum object, 4 flat spectrum objects, 91 Class II objects, and 7 transition disc objects. This classification, together with r'i'H{alpha} IPHAS photometry and JHK UKIDSS photometry, were used for identification of pre-main sequence stars among irregular and periodic variables. In this way, 97 CTTS candidates (96 irregular and one periodic variable), 68 WTTS candidates (54 irregular and 14 periodic variables), and 6 Herbig Ae/Be stars were found. For 223 variable stars we calculated membership probability based on proper motions from Gaia DR2 catalogue. Majority of them, 143 stars, are cluster members with probability greater than 70 per cent. For only 36 variable stars the membership probability is smaller than 20 per cent.
- ID:
- ivo://CDS.VizieR/J/other/RAA/17.20
- Title:
- V977 Cep and V982 Cep long-term photometry
- Short Name:
- J/other/RAA/17.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A49
- Title:
- VCNS II. The IR-excess-selected population
- Short Name:
- J/A+A/585/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a deep wide-field (6.76 square-degrees) near-infrared survey with the VISTA telescope that covers the entire extent of the Carina nebula complex. Complementing the VISTA near-infrared catalog with Spitzer IRAC mid-infrared photometry improves the situation of the background contamination considerably. We find that a (J-H) versus (Ks-[4.5]) color-color diagram is well suited to tracing the population of YSO-candidates (cYSOs) by their infrared excess. We identify 8781 sources with strong infrared excess, which we consider as cYSOs. This sample is used to investigate the spatial distribution of the cYSOs with a nearest-neighbor analysis. The surface density distribution of cYSOs agrees well with the shape of the clouds as seen in our Herschel far-infrared survey. The strong decline in the surface density of excess sources outside the area of the clouds supports the hypothesis that our excess-selected sample consists predominantly of cYSOs with a low level of background contamination.
- ID:
- ivo://CDS.VizieR/J/A+A/379/564
- Title:
- Vega-type and PMS stars UBVRI photo-polarimetry
- Short Name:
- J/A+A/379/564
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table presents optical UBVRI broadband photo-polarimetry of the EXPORT sample obtained at the 2.5m Nordic Optical Telescope. The database consists of multi-epoch photo-polarimetry of 68 pre-main-sequence and main-sequence stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/676/1109
- Title:
- Velocities of stars in the Orion Nebula Cluster
- Short Name:
- J/ApJ/676/1109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 1351 high-resolution spectra of 1215 stars in the Orion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We confirmed 1111 stars as members, based on their radial velocity and/or H{alpha} emission. The radial velocity distribution of members shows a dispersion of {sigma}=3.1km/s. We found a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution, similar to that seen in the molecular gas in the region. We also identified several binary and high velocity stars, a region exhibiting signs of triggered star formation, and a possible foreground population of stars somewhat older than the ONC.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A13
- Title:
- Very low mass objects in ONC
- Short Name:
- J/A+A/515/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Angular momentum (J) loss requires magnetic interaction between the forming star and both the circumstellar disk and the magnetically driven outflows. In order to test these predictions many authors have investigated a rotation-disk connection in pre-main sequence objects with masses larger than about 0.4M_{sun}_. For brown dwarfs (BDs) this connection was not investigated as yet because there are very few samples available. We aim to extend this investigation well down into the substellar regime for our large sample of ~~80 BDs in the Orion Nebula Cluster, for which we have recently measured rotational periods.
