- ID:
- ivo://CDS.VizieR/J/A+A/376/907
- Title:
- Near-IR Sources in the Cederblad 110 region.
- Short Name:
- J/A+A/376/907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of deep (K_s_=18.9) sub-arcsec resolution (0.3") imaging observations of the Cederblad 110 region in the Chamaeleon I dark cloud. This region (roughly 5'x5') is characterized by the presence of six ISOCAM-detected young stellar objects (YSOs). Our images have recovered all these sources at near-infrared (near-IR) wavelengths. Ced 110 IRS4, the brightest object in the region, is associated with a remarkable near-IR bipolar nebulosity. Ced 110 IRS6 is resolved in a double system IRS6a and IRS6b with a separation of ~2" (~320AU at the distance of the Cha I cloud). We have combined 1.3 mm, far and mid-IR fluxes from the literature with our JHK data and obtained the spectral energy distributions (SEDs) for three (IRS4, IRS6a and ISO-ChaI86) of the six ISOCAM sources in the region. We modelled the SEDs of IRS6a and ISO-ChaI86 with a spherically symmetric dusty envelope, using the DUSTY code. These objects are clear Class I sources of the cloud. Finally, we report the detection of three new objects in this region (NIR 72, 84 and 89) with significant near-IR excess. If these sources are associated with the cloud, the derived luminosities and masses suggest that they are candidate young brown dwarfs of Chamaeleon I.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/140/1214
- Title:
- Near-IR spectroscopic survey of class I YSOs
- Short Name:
- J/AJ/140/1214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-IR spectroscopic survey of 110 Class I protostars observed from 0.80um to 2.43um at a spectroscopic resolution of R=1200. This survey is unique in its selection of targets from the whole sky, its sample size, wavelength coverage, depth, and sample selection.
- ID:
- ivo://CDS.VizieR/J/AJ/154/195
- Title:
- New binaries in the {epsilon} Cha association
- Short Name:
- J/AJ/154/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Adaptive Optics-aided speckle observations of 47 young stars in the {epsilon} Cha association made at the 4 m Southern Astrophysical Research Telescope in the I-band. We resolved 10 new binary pairs, 5 previously known binaries, and 2 triple systems, also previously known. In the separation range between 4 and 300 au, the 30 association members of spectral types G0 and later host 6 binary companions, leading to the raw companion frequency of 0.010+/-0.04 per decade of separation, comparable to the main sequence dwarfs in the field. On the other hand, all five massive association members of spectral types A and B have companions in this range. We discuss the newly resolved and known binaries in our sample. Observed motions in the triple system {epsilon} Cha, composed of three similar B9V stars, can be described by tentative orbits with periods 13 and ~900 years and a large mutual inclination.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A21
- Title:
- New Herbig Ae/Be and classical Be stars catalog
- Short Name:
- J/A+A/638/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The intermediate-mass pre-main sequence (PMS) Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. We have applied machine learning techniques to 4150983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Halpha emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars (CBe), with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8+/-1.4% and 85.5+/-1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude.
- ID:
- ivo://CDS.VizieR/J/ApJ/478/603
- Title:
- New Herbig-Haro flows in L1448 and L1455
- Short Name:
- J/ApJ/478/603
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep narrowband H{alpha} and [S II] optical survey of a roughly 1deg^2^ region containing L1448 and L1455 in the southwestern region of the Perseus molecular cloud. We report the detection of 13 new groups of Herbig-Haro (HH) objects in this region. The L1448 core contains eight groups of Herbig-Haro objects (HH 193, HH 194, HH 195, HH 196, HH 197, HH 267, HH 268, and HH 277). Many of the new HH objects near L1448 have orientations similar to the L1448C molecular jet and L1448 IRS3 outflow. All four known infrared sources in L1448 power Herbig-Haro objects. L1448 IRS 1 is the likely source of HH 194, HH 195E, and possibly HH 268. L1448 IRS 2 drives HH 195, and L1448 IRS 3 may power HH 196 and possibly HH 193. HH 267 and HH 277 lie close to the axes of the IRS 2 and IRS 3 flows and may also be powered by one of these sources. Finally, the class 0 source L1448C powers HH 197. The L1455 core contains five new groups of HH objects (HH 278, HH 279, HH 280, HH 317, and HH 318). L1455 IRS 1 and L1455 IRS 2 are likely to power HH objects, but a unique association between each IRAS source and a specific HH object is difficult to make. Both clouds contain some HH objects whose driving sources cannot be conclusively identified. Most of the new HH objects are located near the cloud edges while some are in the interclump medium (ICM) more than 1pc from the nearest cloud core or known young stellar object. These observations provide further evidence that HH flows can extend far beyond the cloud cores containing their sources, and in some cases extend over greater distances than associated high-velocity millimeter-wavelength CO emission. Herbig-Haro objects associated with the terminal working surfaces of outflows located in the ICM can be used to probe the nature of the interclump gas in molecular clouds. The large number of HH objects found in relatively inactive star forming regions such as L1448 and L1455 indicates that shock heating and acceleration by protostellar outflows plays an important role in determining the ionization state and energetics of the ICM that surrounds low-mass star forming regions.
256. New Ori OB1 members
- ID:
- ivo://CDS.VizieR/J/AJ/129/907
- Title:
- New Ori OB1 members
- Short Name:
- J/AJ/129/907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a large-scale, multi-epoch optical survey of the Orion OB1 association, carried out with the QUEST camera at the Venezuela National Astronomical Observatory (CIDA). We identify for the first time the widely spread low-mass, young population in the Ori OB1a and OB1b subassociations. Candidate members were picked up by their variability in the V band and position in color-magnitude diagrams. We obtained spectra to confirm membership. In a region spanning ~68{deg}^2^, we found 197 new young stars; of these, 56 are located in the Ori OB1a subassociation and 141 in Ori OB1b.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/2737
- Title:
- New PMS K/M Stars in Upper Scorpius
- Short Name:
- J/MNRAS/448/2737
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 237 new spectroscopically confirmed pre-main-sequence K- and M-type stars in the young Upper Scorpius subgroup of the Sco-Cen association, the nearest region of recent massive star formation. Using the Wide-Field Spectrograph at the Australian National University 2.3 m telescope at Siding Spring, we observed 397 kinematically and photometrically selected candidate members of Upper Scorpius, and identified new members by the presence of lithium absorption. The HR-diagram of the new members shows a spread of ages, ranging from ~3 to 20Myr, which broadly agrees with the current age estimates of ~5-10Myr. We find a significant range of Li 6708 equivalent widths among the members, and a minor dependence of HR-diagram position on the measured equivalent width of the Li 6708{AA} line, with members that appear younger having more lithium. This could indicate the presence of either populations of different age, or a spread of ages in Upper Scorpius. We also use Wide-Field Infrared Survey Explorer data to infer circumstellar disc presence in 25 of the members on the basis of infrared excesses, including two candidate transition discs. We find that 11.2+/-3.4% the M0-M2 spectral type (0.4-0.8M_{sun}_) Upper Sco stars display an excess that indicates the presence of a gaseous disc.
- ID:
- ivo://CDS.VizieR/J/A+A/375/130
- Title:
- New PMS spectroscopic binaries in Orion
- Short Name:
- J/A+A/375/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 2 contains the heliocentric radial velocity data versus Heliocentric Julian Day for six X-ray selected double-lined spectroscopic binaries in Orion. Of these, the four systems RXJ 0529.4+0041, RXJ 0530.7-0434, RXJ 0532.1-0732, and RXJ 0541.4-0324 are pre-main sequence systems. Table 3 contains the radial velocity data for the third components of the spectroscopic systems RXJ 0441.0-0839, RXJ 0529.4+0041, and RXJ 0532.1-0732
- ID:
- ivo://CDS.VizieR/J/AJ/134/1162
- Title:
- 11 new T dwarfs in 2MASS
- Short Name:
- J/AJ/134/1162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of 11 new T dwarfs, found during the course of a photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog and from a proper-motion-selected sample of ultracool dwarfs in the 2MASS Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph, we obtained low-resolution (R~150) spectroscopy, allowing us to derive near-infrared spectral types of T2-T8. We also present improved signal-to-noise ratio SpeX low-resolution spectroscopy of the near-infrared T0 standard SDSS J120747.17+024424.8 and T1 standard SDSSp J083717.22-000018.3. One of these new T dwarfs, 2MASS J13243559+6358284, was also discovered independently by Metchev et al.
- ID:
- ivo://CDS.VizieR/J/A+A/312/439
- Title:
- New T Tauri stars in Taurus-Auriga
- Short Name:
- J/A+A/312/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of the ROSAT All-Sky-Survey, a study of the Taurus-Auriga star forming region has been performed in order to search for hitherto undiscovered T Tauri stars. Our study covers an area of about 280 square degrees, located between 4^h^ and 5^h^ in right ascension and between 15deg and 34deg in declination. Identification of ROSAT All-Sky Survey sources in this area by means of optical spectroscopy revealed 2 new classical T Tauri stars (CTTS) and 66 new weak-line-T Tauri stars (WTTS) with W_{lambda}_(H{alpha})<=10A. Additional pointed ROSAT observations led to the identification of 6 more WTTS and 2 CTTS, giving a total of 76 new T Tauri stars. The large area of our study, as compared with previous works, allows us to study the spatial distribution of WTTS in this star forming region. We find the WTTS of our survey to be distributed over the whole region investigated. There is a noticeable decline of the surface density from south to north within our study area, but the spatial distribution extends most probably beyond our study region. No clustering towards the population of T Tauri stars known prior to ROSAT in Taurus-Auriga could be observed. We suggest that the WTTS found in our study might in part be somewhat older than the previously known T Tauri stars in Taurus-Auriga, and that their broad spatial distribution is due to the typical velocity dispersion of a few km/s measured for Taurus T Tauri stars, in which case for some of our WTTS an age on the order of 10^7^years would be required for reaching the observed distances from the Taurus dark clouds. We estimate a WTTS/CTTS ratio of about 6 within our study area, but conclude that because of the different spatial distribution of WTTS and CTTS this ratio will be most probably significantly larger for a more extended area.
