- ID:
- ivo://CDS.VizieR/J/AJ/150/17
- Title:
- A catalog of point sources toward NGC 1333
- Short Name:
- J/AJ/150/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present a catalog of point-source objects toward NGC 1333, resolving a wide variety of confusion about source names (and occasionally positions) in the literature. I incorporate data from optical to radio wavelengths, but focus most of the effort on being complete and accurate from J (1.25{mu}m) to 24{mu}m. The catalog encompasses 52^{deg}^<R.A.<52.5{deg} and 31{deg}<decl.<31.6{deg}. Cross-identifications include those from more than 25 papers and catalogs from 1994 to 2014, primarily those in wide use as origins of nomenclature. Gaps in our knowledge are identified, with the most important being a lack of spectroscopy for spectral types or even confirmation of youth and/or cluster membership. I fit a slope to the spectral energy distribution (SED) between 2 and 24{mu}m for the members (and candidate members) to obtain an SED classification, and I compare the resulting classes to those for the same sources in the literature, and for an SED fit between 2 and 8{mu}m. While there are certainly differences, for the majority of the sources, there is good agreement.
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- ID:
- ivo://CDS.VizieR/J/ApJ/710/597
- Title:
- Accretion in disks in Cep OB2
- Short Name:
- J/ApJ/710/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present accretion rates for a large number of solar-type stars in the Cep OB2 region, based on U-band observations. Our study comprises 95 members of the ~4Myr old cluster Tr 37 (including 20 "transition" objects (TOs)), as well as the only classical T Tauri star (CTTS) in the ~12Myr old cluster NGC 7160. The stars show different disk morphologies, with the majority of them having evolved and flattened disks. The typical accretion rates are about 1 order of magnitude lower than in regions aged 1-2Myr, and we find no strong correlation between disk morphology and accretion rates. Although half of the TOs are not accreting, the median accretion rates of normal CTTS and accreting "transition" disks are similar (~3x10^-9^ and 2x10^-9^M_{sun}_/yr, respectively). Comparison with other regions suggests that the TOs observed at different ages do not necessarily represent the same type of objects, which is consistent with the fact that the different processes that can lead to reduced IR excess/inner disk clearing (e.g., binarity, dust coagulation/settling, photoevaporation, giant planet formation) do not operate on the same timescales.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/21
- Title:
- Accretion luminosities of young stars from Pf{beta}
- Short Name:
- J/ApJ/769/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we introduce the use of HI Pfund {beta} (Pf{beta}; 4.6538{mu}m) as a tracer of mass accretion from protoplanetary disks onto young stars. Pf{beta} was serendipitously observed in NIRSPEC and CRIRES surveys of CO fundamental emission, amounting to a sample size of 120 young stars with detected Pf{beta} emission. Using a subsample of disks with previously measured accretion luminosities, we show that Pf{beta} line luminosity is well correlated with accretion luminosity over a range of at least three orders of magnitude. We use this correlation to derive accretion luminosities for all 120 targets, 65 of which are previously unreported in the literature. The conversion from accretion luminosity to accretion rate is limited by the availability of stellar mass and radius measurements; nevertheless, we also report accretion rates for 67 targets, 16 previously unmeasured. Our large sample size and our ability to probe high extinction values allow for relatively unbiased comparisons between different types of disks.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/6
- Title:
- AllWISE & NEOWISE LCs of Red MSX massive YSOs
- Short Name:
- J/ApJ/883/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We systematically investigate the mid-infrared (MIR; {lambda}>3{mu}m) time variability of uniformly selected ~800 massive young stellar objects (MYSOs) from the Red Midcourse Space Experiment Source survey. Out of the 806 sources, we obtain reliable 9yr long MIR magnitude variability data of 331 sources at the 3.4{mu}m (W1) and 4.6{mu}m (W2) bands by cross-matching the MYSO positions with ALLWISE and NEOWISE catalogs. After applying the variability selections using ALLWISE data, we identify five MIR-variable candidates. The light curves show various classes, with the periodic, plateau-like, and dipper features. Out of the obtained two color-magnitude diagram of W1 and W1-W2, one shows "bluer when brighter and redder when fainter" trends in variability, suggesting change in extinction or accretion rate. Finally, our results show that G335.9960-00.8532 has a periodic light curve, with an ~690d cycle. Spectral energy density model fitting results indicate that G335.9960-00.8532 is a relatively evolved MYSO; thus, we may be witnessing the very early stages of a hyper- or ultra-compact HII region, a key source for understanding MYSO evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/826/16
- Title:
- ALMA and GeMS observations of the OMC1 region
- Short Name:
- J/ApJ/826/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ALMA observations of the Orion Nebula that cover the OMC1 outflow region. Our focus in this paper is on compact emission from protoplanetary disks. We mosaicked a field containing ~600 near-IR-identified young stars, around which we can search for sub-millimeter emission tracing dusty disks. Approximately 100 sources are known proplyds identified with the Hubble Space Telescope. We detect continuum emission at 1mm wavelengths toward ~20% of the proplyd sample, and ~8% of the larger sample of near-IR objects. The noise in our maps allows 4{sigma} detection of objects brighter than ~1.5mJy, corresponding to protoplanetary disk masses larger than 1.5M_J_ (using standard assumptions about dust opacities and gas-to-dust ratios). None of these disks are detected in contemporaneous CO(2-1) or C^18^O(2-1) observations, suggesting that the gas-to-dust ratios may be substantially smaller than the canonical value of 100. Furthermore, since dust grains may already be sequestered in large bodies in Orion Nebula cluster (ONC) disks, the inferred masses of disk solids may be underestimated. Our results suggest that the distribution of disk masses in this region is compatible with the detection rate of massive planets around M dwarfs, which are the dominant stellar constituent in the ONC.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/20
- Title:
- ALMA survey of Orion PGCCs (ALMASOP). II. 1.3mm
- Short Name:
- J/ApJS/251/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planck Galactic Cold Clumps (PGCCs) are considered to be the ideal targets to probe the early phases of star formation. We have conducted a survey of 72 young dense cores inside PGCCs in the Orion complex with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3mm (band 6) using three different configurations (resolutions ~0.35", 1.0", and 7.0") to statistically investigate their evolutionary stages and substructures. We have obtained images of the 1.3mm continuum and molecular line emission (^12^CO, and SiO) at an angular resolution of ~0.35" (~140au) with the combined arrays. We find 70 substructures within 48 detected dense cores with median dust mass ~0.093M_{sun}_ and deconvolved size ~0.27". Dense substructures are clearly detected within the central 1000au of four candidate prestellar cores. The sizes and masses of the substructures in continuum emission are found to be significantly reduced with protostellar evolution from Class 0 to Class I. We also study the evolutionary change in the outflow characteristics through the course of protostellar mass accretion. A total of 37 sources exhibit CO outflows, and 20 (>50%) show high-velocity jets in SiO. The CO velocity extents ({Delta}Vs) span from 4 to 110km/s with outflow cavity opening angle width at 400au ranging from [{Theta}_obs_]_400_~0.6"-3.9", which corresponds to 33.4{deg}-125.7{deg}. For the majority of the outflow sources, the {Delta}Vs show a positive correlation with [{Theta}_obs_]_400_, suggesting that as protostars undergo gravitational collapse, the cavity opening of a protostellar outflow widens and the protostars possibly generate more energetic outflows.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/14
- Title:
- A Pan-Carina YSO catalog
- Short Name:
- J/ApJS/194/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 1439 young stellar objects (YSOs) spanning the 1.42deg^2^ field surveyed by the Chandra Carina Complex Project (CCCP), which includes the major ionizing clusters and the most active sites of ongoing star formation within the Great Nebula in Carina. Candidate YSOs were identified via infrared (IR) excess emission from dusty circumstellar disks and envelopes, using data from the Spitzer Space Telescope (the Vela-Carina survey) and the Two-Micron All Sky Survey. We model the 1-24um IR spectral energy distributions of the YSOs to constrain physical properties. Our Pan-Carina YSO Catalog (PCYC) is dominated by intermediate-mass (2M_{sun}_<m<~10M_{sun}_) objects with disks, including Herbig Ae/Be stars and their less evolved progenitors. The PCYC provides a valuable complementary data set to the CCCP X-ray source catalogs, identifying 1029 YSOs in Carina with no X-ray detection. We also catalog 410 YSOs with X-ray counterparts, including 62 candidate protostars. Extrapolating over the stellar initial mass function scaled to the PCYC population, we predict a total population of >2x10^4^ YSOs and a present-day star formation rate (SFR) of >0.008M_{sun}_/yr. The global SFR in the Carina Nebula, averaged over the past ~5Myr, has been approximately constant.
- ID:
- ivo://CDS.VizieR/J/ApJ/767/36
- Title:
- APEX observations of HOPS protostars
- Short Name:
- J/ApJ/767/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument on board the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel Orion Protostar Survey (HOPS). A total of 55 new protostar candidates are detected at 70{mu}m and 160{mu}m that are either too faint (m_24_>7mag) to be reliably classified as protostars or undetected in the Spitzer/MIPS 24{mu}m band. We find that the 11 reddest protostar candidates with log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65 are free of contamination and can thus be reliably explained as protostars. The remaining 44 sources have less extreme 70/24 colors, fainter 70{mu}m fluxes, and higher levels of contamination. Taking the previously known sample of Spitzer protostars and the new sample together, we find 18 sources that have log{lambda}F_{lambda}_70/{lambda}F_{lambda}_24>1.65; we name these sources "PACS Bright Red sources," or PBRs. Our analysis reveals that the PBR sample is composed of Class 0 like sources characterized by very red spectral energy distributions (SEDs; T_bol_<45K) and large values of sub-millimeter fluxes (L_smm_/L_bol_>0.6%). Modified blackbody fits to the SEDs provide lower limits to the envelope masses of 0.2-2M_{sun}_ and luminosities of 0.7-10L_{sun}_. Based on these properties, and a comparison of the SEDs with radiative transfer models of protostars, we conclude that the PBRs are most likely extreme Class 0 objects distinguished by higher than typical envelope densities and hence, high mass infall rates.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/27
- Title:
- APOGEE-2 survey of Orion Complex (OSFC). I.
- Short Name:
- J/ApJS/236/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Orion Star-forming Complex (OSFC) is a central target for the APOGEE-2 Young Cluster Survey. Existing membership catalogs span limited portions of the OSFC, reflecting the difficulty of selecting targets homogeneously across this extended, highly structured region. We have used data from wide-field photometric surveys to produce a less biased parent sample of young stellar objects (YSOs) with infrared (IR) excesses indicative of warm circumstellar material or photometric variability at optical wavelengths across the full 420deg^2^ extent of the OSFC. When restricted to YSO candidates with H<12.4, to ensure S/N~100 for a six-visit source, this uniformly selected sample includes 1307 IR excess sources selected using criteria vetted by Koenig & Leisawitz (2014ApJ...791..131K) and 990 optical variables identified in the Pan-STARRS1 3{pi} survey: 319 sources exhibit both optical variability and evidence of circumstellar disks through IR excess. Objects from this uniformly selected sample received the highest priority for targeting, but required fewer than half of the fibers on each APOGEE-2 plate. We filled the remaining fibers with previously confirmed and new color-magnitude selected candidate OSFC members. Radial velocity measurements from APOGEE-1 and new APOGEE-2 observations taken in the survey's first year indicate that ~90% of the uniformly selected targets have radial velocities consistent with Orion membership. The APOGEE-2 Orion survey will include >1100 bona fide YSOs whose uniform selection function will provide a robust sample for comparative analyses of the stellar populations and properties across all sub-regions of Orion.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/59
- Title:
- A search for YSO candidates in IRDC G53.2
- Short Name:
- J/ApJ/802/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present star formation activity in the infrared dark cloud (IRDC) G53.2, a remarkable IRDC located at Galactic coordinates (l,b)~(53.2{deg},0.0{deg}) based on the census of young stellar object (YSO) candidates. IRDC G53.2 was previously identified as several IRDCs in mid-IR images, but it is in fact a long (>~45pc) cloud, well consistent with a CO cloud at v~23km/s (or at d~1.7kpc). We present a point-source catalog of IRDC G53.2 that contains ~370 sources from our photometry of the Spitzer MIPS 24{mu}m data and Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) Catalog. The classification of the identified sources based on their spectral index and control field analysis to remove field star contamination reveals that IRDC G53.2 is an active star-forming region with ~300 YSO candidates. We compare the YSO classification based on spectral index, mid-IR colors, and the wavelength range used, which results in consistent classification, except for flat-spectrum objects, with some ambiguity between Class I and II. Comparison of the YSO population in IRDC G53.2 with those of other nearby star-forming clusters indicates that they are similar in age; on the other hand, stronger association with mid-IR stellar sources in IRDC G53.2 compared with other IRDCs indicates that IRDC G53.2 is at a later evolutionary stage among IRDCs. Spatial distribution of the YSO candidates in IRDC G53.2 shows a good correlation with ^13^CO column density and far-IR emission, and earlier-class objects tend to be more clustered in the regions with higher density.
