- 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/A+A/599/A23
- Title:
- Accretion-rotation connection in NGC 2264
- Short Name:
- J/A+A/599/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The low spin rates measured for solar-type stars at an age of a few Myr (~10% of the break-up velocity) indicate that some mechanism of angular momentum regulation must be at play in the early pre-main sequence. This may be associated with magnetospheric accretion and star-disk interaction, as suggested by observations that disk-bearing objects (CTTS) are slower rotators than diskless sources (WTTS) in young star clusters. We characterize the rotation properties for members of the star-forming region NGC 2264 (~3Myr) as a function of mass, and investigate the accretion-rotation connection at an age where about 50% of the stars have already lost their disks. We examined a sample of 500 cluster members (40% with disks, 60% without disks), distributed in mass between ~0.15 and 2M_{sun}_, whose photometric variations were monitored in the optical for 38 consecutive days with the CoRoT space observatory. Light curves were analyzed for periodicity using three different techniques: the Lomb-Scargle periodogram, the autocorrelation function and the string-length method. Periods were searched in the range between 0.17-days (i.e., 4h, twice the data sampling adopted) and 19-days (half the total time span). Period detections were confirmed using a variety of statistical tools (false alarm probability, Q-statistics), as well as visual inspection of the direct and phase-folded light curves.
- ID:
- ivo://CDS.VizieR/J/ApJS/125/161
- Title:
- A database of dense cores mapped in ammonia
- Short Name:
- J/ApJS/125/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a database of 264 cores mapped in the (J,K)=(1,1) and (2,2) lines of NH_3_. We list the core gas properties-peak positions, total ammonia column densities, intrinsic line widths, kinetic temperatures, volume densities, core sizes, aspect ratios, and velocity gradients, as well as the properties of associated young stellar objects (YSOs)-associated IRAS sources along with their luminosities and core-YSO distances, outflow velocities, and SIMBAD and cluster associations. We also present the results of our statistical analysis and enumerate important pairwise correlations among the various gas and YSO properties.
- ID:
- ivo://CDS.VizieR/J/MNRAS/502/6117
- Title:
- A faint companion around CrA-9
- Short Name:
- J/MNRAS/502/6117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Understanding how giant planets form requires observational input from directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to search for companions in the transition disc of 2MASS J19005804-3645048 (hereafter CrA-9), an accreting M0.75 dwarf with an estimated age of 1-2Myr. We found a faint point source at ~0.7-arcsec separation from CrA-9 (~108au projected separation). Our 3-epoch astrometry rejects a fixed background star with a 5{sigma} significance. The near-IR absolute magnitudes of the object point towards a planetary-mass companion. However, our analysis of the 1.0-3.8um spectrum extracted for the companion suggests it is a young M5.5 dwarf, based on both the 1.13um Na index and comparison with templates of the Montreal Spectral Library. The observed spectrum is best reproduced with high effective temperature (3057^+119^_-36_K) BT-DUSTY and BT-SETTL models, but the corresponding photometric radius required to match the measured flux is only 0.60^+0.01^_-0.04_ Jovian radius. We discuss possible explanations to reconcile our measurements, including an M-dwarf companion obscured by an edge-on circum-secondary disc or the shock-heated part of the photosphere of an accreting protoplanet. Follow-up observations covering a larger wavelength range and/or at finer spectral resolution are required to discriminate these two scenarios.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A43
- Title:
- AFGL 2591 multi-wavelength maps
- Short Name:
- J/A+A/551/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While it is currently unclear from a theoretical standpoint which forces and processes dominate the formation of high-mass stars, and hence determine the mode in which they form, much of the recent observational evidence suggests that massive stars are born in a similar manner to their low-mass counterparts. This paper aims to investigate the hypothesis that the embedded luminous star AFGL 2591-VLA 3 (2.3E+5L_{sun}_ at 3.33kpc) is forming according to a scaled-up version of a low-mass star formation scenario. We present multi-configuration Very Large Array 3.6cm and 7mm, as well as Combined Array for Research in Millimeter Astronomy C^18^O and 3mm continuum observations to investigate the morphology and kinematics of the ionized gas, dust, and molecular gas around AFGL 2591. We also compare our results to ancillary Gemini North near-IR images, and model the near-IR to sub-mm Spectral Energy distribution (SED) and Two Micron All Sky Survey (2MASS) image profiles of AFGL 2591 using a Monte-Carlo dust continuum radiative transfer code. The observed 3.6 cm images uncover for the first time that the central powering source AFGL 2591-VLA 3 has a compact core plus collimated jet morphology, extending 4000AU eastward from the central source with an opening angle of <10{deg} at this radius. However, at 7mm VLA 3 does not show a jet morphology, but instead compact (< 500AU) emission, some of which (<0.57mJy of 2.9mJy) is estimated to be from dust emission. The spectral index of AFGL 2591-VLA 3 between 3.6cm and 7mm was found to be between 0.4 and 0.5, similar to that of an ionized wind. If the 3.6cm emission is modelled as an ionized jet, the jet has almost enough momentum to drive the larger-scale flow. However, assuming a shock efficiency of 10%, the momentum rate of the jet is not sufficient to ionize itself via only shocks, and thus a significant portion of the emission is instead likely created in a photoionized wind. The C18O emission uncovers dense entrained material in the outflow(s) from these young stars. The main features of the SED and 2MASS images of AFGL 2591-VLA 3 are also reproduced by our model dust geometry of a rotationally flattened envelope with and without a disk. The above results are consistent with a picture of massive star formation similar to that seen for low-mass protostars. However, within its envelope, AFGL 2591-VLA 3 contains at least four other young stars, constituting a small cluster. Therefore it appears that AFGL 2591-VLA 3 may be able to source its accreting material from a shared gas reservoir while still exhibiting the phenomena expected during the formation of low-mass stars.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A84
- Title:
- AFGL 2591-VLA 3 IRAM/NOEMA datacubes
- Short Name:
- J/A+A/655/A84
- Date:
- 10 Mar 2022 07:32:39
- Publisher:
- CDS
- Description:
- Increasing evidence suggests that, similar to their low-mass counterparts, high-mass stars form through a disk-mediated accretion process. At the same time, formation of high-mass stars still necessitates high accretion rates, and hence, high gas densities, which in turn can cause disks to become unstable against gravitational fragmentation. We study the kinematics and fragmentation of the disk around the high-mass star forming region AFGL 2591-VLA 3 which was hypothesized to be fragmenting based on the observations that show multiple outflow directions. We use a new set of high-resolution (0.19-arcsec) IRAM/NOEMA observations at 843 micron towards VLA 3 which allow us to resolve its disk, characterize the fragmentation, and study its kinematics. In addition to the 843 micron continuum emission, our spectral setup targets warm dense gas and outflow tracers such as HCN, HC_3_N and SO_2_, as well as vibrationally excited HCN lines. The high resolution continuum and line emission maps reveal multiple fragments with subsolar masses within the inner 1000AU of VLA 3. Furthermore, the velocity field of the inner disk observed at 843 micron shows a similar behavior to that of the larger scale velocity field studied in the CORE project at 1.37mm. We present the first observational evidence for disk fragmentation towards AFGL 2591-VLA 3, a source that was thought to be a single high-mass core. While the fragments themselves are low-mass, the rotation of the disk is dominated by the protostar with a mass of 10.3+/-1.8M_{sun}_. These data also show that NOEMA Band 4 can obtain the highest currently achievable spatial resolution at (sub-)mm wavelengths in observations of strong northern sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/868/32
- Title:
- A large moving group within the LCC association
- Short Name:
- J/ApJ/868/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Scorpius-Centaurus is the nearest OB association, and its hundreds of members are divided into subgroups, including the Lower Centaurus Crux (LCC). Here we study the dynamics of the LCC area. We report the revelation of a large moving group containing more than 1800 intermediate- and low-mass young stellar objects and brown dwarfs that escaped identification until Gaia DR2 allowed a kinematic and photometric selection to be performed. We investigate the stellar and substellar content of this moving group using the Gaia DR2 astrometric and photometric measurements. The median distance of the members is 114.5pc, and 80% lie between 102 and 135pc from the Sun. Our new members cover a mass range of 0.02-5M_{sun}_ and add up to a total mass of about 700M_{sun}_. The present-day mass function follows a log-normal law with m_c_=0.22M_{sun}_ and {sigma}=0.64. We find more than 200 brown dwarfs in our sample. The star formation rate had its maximum of 8x10^-5^M_{sun}_/yr about 9Myr ago. We grouped the new members into four denser subgroups, which have increasing age from 7 to 10Myr, surrounded by "free-floating" young stars with mixed ages. Our isochronal ages, now based on accurate parallaxes, are compatible with several earlier studies of the region. The whole complex is presently expanding, and the expansion started between 8 and 10Myr ago. Two hundred members show infrared excess compatible with circumstellar disks from full to debris disks. This discovery provides a large sample of nearby young stellar and substellar objects for disk and exoplanet studies.
- 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.
