- ID:
- ivo://CDS.VizieR/J/A+A/550/A83
- Title:
- NIR observations of CG1 and CG2
- Short Name:
- J/A+A/550/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cometary globules CG1 and CG2 are "classical" cometary globules in the Gum Nebula region at a distance of ~300pc. The objective of this study is to examine the mass distribution and the structure of CG1 and CG2 through extinction, and to study the star formation activity in CG1 and CG2. The NIR JHKs photometry is used in creating visual extinction maps.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/741/35
- Title:
- NIR photometry and polarization in NGC 2264
- Short Name:
- J/ApJ/741/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared imaging polarimetry in the J, H, and Ks bands has been carried out for the protostellar cluster region around NGC 2264 IRS 2 in the Monoceros OB1 molecular cloud. Various infrared reflection nebula clusters (IRNCs) associated with NGC 2264 IRS 2 and the IRAS 12 S1 core, as well as local infrared reflection nebulae (IRNe), were detected. The illuminating sources of the IRNe were identified with known or new near- and mid-infrared sources. In addition, 314 point-like sources were detected in all three bands and their aperture polarimetry was studied. Using a color-color diagram, reddened field stars and diskless pre-main-sequence stars were selected to trace the magnetic field (MF) structure of the molecular cloud. The mean polarization position angle of the point-like sources is 81+/-29{deg} in the cluster core, and 58+/-24{deg} in the perimeter of the cluster core, which is interpreted as the projected direction on the sky of the MF in the observed region of the cloud. The Chandrasekhar-Fermi method gives a rough estimate of the MF strength to be about 100uG. A comparison with recent numerical simulations of the cluster formation implies that the cloud dynamics is controlled by the relatively strong MF. The local MF direction is well associated with that of CO outflow for IRAS 12 S1 and consistent with that inferred from submillimeter polarimetry. In contrast, the local MF direction runs roughly perpendicular to the Galactic MF direction.
283. NIR sources in S106
- ID:
- ivo://CDS.VizieR/J/AJ/131/1608
- Title:
- NIR sources in S106
- Short Name:
- J/AJ/131/1608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of deep near-infrared observations searching for very low mass young stellar objects (YSOs) in the massive star-forming region of S106 taken with the Subaru Telescope. The survey, whose limiting magnitude exceeds 20mag in the JHK' bands, is sensitive enough to provide unprecedented details in the two nebular lobes. In addition, it reveals a census of the stellar population down to objects below the deuterium-burning limit, a fiducial boundary between brown dwarfs and planetary-mass objects. Based on color-color diagrams, nearly 600 embedded YSO candidates with near-infrared excesses have been identified in an area of ~5'x5' that are not uniformly distributed but centrally concentrated.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/L9
- Title:
- ODISEA: Disk dust mass distributions
- Short Name:
- J/ApJ/875/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As protostars evolve from optically faint/infrared-bright (Class I) sources to optically bright/infrared-faint (Class II) the solid material in their surrounding disks accumulates into planetesimals and protoplanets. The nearby, young Ophiuchus star-forming region contains hundreds of protostars in a range of evolutionary states. Using the Atacama Large Millimeter Array to observe their millimeter continuum emission, we have measured masses of, or placed strong upper limits on, the dust content of 279 disks. The masses follow a log-normal distribution with a clear trend of decreasing mass from less to more evolved protostellar infrared class. The (logarithmic) mean Class I disk mass, M=3.8M_{Earth}_, is about 5 times greater than the mean Class II disk mass, but the dispersion in each class is so high, {sigma}_logM_~0.8-1, that there is a large overlap between the two distributions. The disk mass distribution of flat-spectrum protostars lies in between Classes I and II. In addition, three Class III sources with little to no infrared excess are detected with low disk masses, M~0.3M_{Earth}_. Despite the clear trend of decreasing disk mass with protostellar evolutionary state in this region, a comparison with surveys of Class II disks in other regions shows that masses do not decrease monotonically with age. This suggests that the cloud-scale environment may determine the initial disk mass scale or that there is substantial dust regeneration after 1Myr.
- ID:
- ivo://CDS.VizieR/J/AJ/121/1676
- Title:
- ONC low-mass stars photometry
- Short Name:
- J/AJ/121/1676
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have photometrically monitored ~3600 young, low-mass stars in four 45'x45' fields in the outer Orion Nebula cluster, surrounding but not including the Trapezium region.
- ID:
- ivo://CDS.VizieR/J/MNRAS/482/698
- Title:
- Ophiuchus DIsc Survey Employing ALMA (ODISEA). I.
- Short Name:
- J/MNRAS/482/698
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the entire population of Spitzer-selected protoplanetary discs in the Ophiuchus Molecular Cloud (~300 objects) from both millimetre continuum and CO isotopologues data. Here we present 1.3mm/230GHz continuum images of 147 targets at 0.2" (28au) resolution and a typical rms of 0.15mJy. We detect a total of 133 discs, including the individual components of 11 binary systems and 1 triple system. 60 of these discs are spatially resolved. We find clear substructures (inner cavities, rings, gaps, and/or spiral arms) in eight of the sources and hints of such structures in another four discs. We construct the disc luminosity function for our targets and perform preliminary comparisons to other regions. A simple conversion between flux and dust mass (adopting standard assumptions) indicates that all discs detected at 1.3mm are massive enough to form one or more rocky planets. In contrast, only ~50 discs (~1/3 of the sample) have enough mass in the form of dust to form the canonical 10M_{Earth}_ core needed to trigger runaway gas accretion and the formation of gas giant planets, although the total mass of solids already incorporated into bodies larger than cm scales is mostly unconstrained. The distribution in continuum disc sizes in our sample is heavily weighted towards compact discs: most detected discs have radii <15au, while only 23 discs (~15% of the targets) have radii >30au.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A29
- Title:
- Optical and near-infrared photometry in Orion A
- Short Name:
- J/A+A/564/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the recent discovery a large population of young stars in front of the Orion Nebula we carried out an observational campaign with the DECam wide-field camera covering approximately 10 square degrees centered on NGC 1980 to confirm, probe the extent, and characterize this foreground population of pre-main sequence stars. We used multi-wavelength wide field images and catalogs to identify potential foreground pre-main sequence stars using a novel probabilistic technique based on a careful selection of colors and luminosities. We confirmed the presence of a large foreground population towards the Orion A cloud. This population contains several distinct sub-groups including NGC 1980 and NGC 1981 and stretches over several degrees in front of the Orion A cloud. By comparing the location of their sequence in various color-magnitude diagrams to other clusters, we found a distance and an age of 380pc and 5 to 10Myr, in good agreement with previous estimates. Our final sample includes 2123 candidate members and is complete from below the hydrogen burning limit to about 0.3M_{sun}_ where the data starts to be limited by saturation. Extrapolating the mass function to the high masses, we estimated a total number of ~2600 members in the surveyed region.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/704
- Title:
- Optical and X-ray variability of ONC PMS
- Short Name:
- J/ApJ/660/704
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical analysis of simultaneous optical and X-ray light curves, spanning 600ks, for 814 pre-main-sequence (PMS) stars in the Orion Nebula Cluster. The aim of this study is to establish the relationship, if any, between the sites of optical and X-ray variability and thereby to elucidate the origins of X-ray production in PMS stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1542
- Title:
- Optical high-resolution spectroscopy of WTTSs
- Short Name:
- J/ApJ/723/1542
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution spectroscopic observations for a sample of 19 weak-line T Tauri stars (WTTSs). Based on these observations and data of 108 WTTSs taken from the literature, we derive lithium abundances for 127 WTTSs. Investigation of a possible relation between lithium and rotation in WTTSs shows that: (1) rapidly rotating WTTSs have comparatively lower lithium abundances than their slower rotating counterparts; (2) in the spectral-type range G0-K0, most of the WTTSs share the same Li content irrespective of their Teff; and (3) active late-type binaries do not obey the correlation between lithium abundances and rotation periods, since the tidally locked rotation of the late-type binary system leads naturally to slower lithium destruction rates.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/481
- Title:
- Optical/IR photometry of Collinder 69
- Short Name:
- J/ApJ/664/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiwavelength optical and IR photometry of 170 previously known low-mass stars and brown dwarfs of the 5Myr Collinder 69 cluster ({lambda} Orionis). The new photometry supports cluster membership for most of them, with less than 15% of the previous candidates identified as probable nonmembers. The near-IR photometry allows us to identify stars with IR excesses, and we find that the Class II population is very large, around 25% for stars (in the spectral range M0-M6.5) and 40% for brown dwarfs, down to 0.04M_{sun}_, despite the fact that the H{alpha} equivalent width is low for a significant fraction of them. In addition, there are a number of substellar objects, classified as Class III, that have optically thin disks. The Class II members are distributed in an inhomogeneous way, lying preferentially in a filament running toward the southeast. The IR excesses for the Collinder 69 members range from pure Class II (flat or nearly flat spectra longward of 1um), to transition disks with no near-IR excess but excesses beginning within the IRAC wavelength range, to two stars with excess only detected at 24um. Collinder 69 thus appears to be at an age where it provides a natural laboratory for the study of primordial disks and their dissipation.
