- ID:
- ivo://CDS.VizieR/J/PASP/125/477
- Title:
- Gas Survey of Protoplanetary Systems. I.
- Short Name:
- J/PASP/125/477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris disk systems carried out using the ACS instrument on the Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey of Protoplanetary Systems), targeted ~250 young stars in narrow wavelength regions covering the [OI] fine structure line at 63um the brightest far-infrared line in such objects. A subset of the brightest targets were also surveyed in [OI]145um, [CII] at 157um, as well as several transitions of HO and high-excitation CO lines at selected wavelengths between 78 and 180um. Additionally, GASPS included continuum photometry at 70, 100 and 160um, around the peak of the dust emission.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/835/3
- Title:
- 218GHz obs. of embedded protostars in Ophiuchus
- Short Name:
- J/ApJ/835/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present APEX 218GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H_2_CO and c-C_3_H_2_ rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H_2_CO temperatures range between 16K and 124K, with the highest H_2_CO temperatures toward the hot corino source IRAS 16293-2422 (69-124K) and the sources in the {rho} Oph A cloud (23-49K) located close to the luminous Herbig Be star S1, which externally irradiates the {rho} Oph A cores. On the other hand, the c-C_3_H_2_ rotational temperature is consistently low (7-17K) in all sources. Our results indicate that the c-C_3_H_2_ emission is primarily tracing more shielded parts of the envelope whereas the H_2_CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS 16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.
- ID:
- ivo://CDS.VizieR/J/ApJ/845/44
- Title:
- 340GHz SMA obs. of 50 nearby protoplanetary disks
- Short Name:
- J/ApJ/845/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a survey at subarcsecond resolution of the 340GHz dust continuum emission from 50 nearby protoplanetary disks, based on new and archival observations with the Submillimeter Array. The observed visibility data were modeled with a simple prescription for the radial surface brightness profile. The results were used to extract intuitive, empirical estimates of the emission "size" for each disk, R_eff_, defined as the radius that encircles a fixed fraction of the total continuum luminosity, L_mm_. We find a significant correlation between the sizes and luminosities, such that R_eff_{propto}L_mm_^0.5^, providing a confirmation and quantitative characterization of a putative trend that was noted previously. This correlation suggests that these disks have roughly the same average surface brightness interior to their given effective radius, ~0.2Jy/arcsec^2^ (or 8K in brightness temperature). The same trend remains, but the 0.2dex of dispersion perpendicular to this relation essentially disappears, when we account for the irradiation environment of each disk with a crude approximation of the dust temperatures based on the stellar host luminosities. We consider two (not mutually exclusive) explanations for the origin of this size-luminosity relationship. Simple models of the growth and migration of disk solids can account for the observed trend for a reasonable range of initial conditions, but only on timescales that are much shorter than the nominal ages present in the sample. An alternative scenario invokes optically thick emission concentrated on unresolved scales, with filling factors of a few tens of percent, which is perhaps a manifestation of localized particle traps.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A131
- Title:
- Giant molecular filaments in the Milky Way
- Short Name:
- J/A+A/590/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Filamentary structures are common morphological features of the cold, molecular interstellar medium (ISM). Recent studies have discovered massive, hundred-parsec-scale filaments that may be connected to the large-scale, Galactic spiral arm structure. Addressing the nature of these giant molecular filaments (GMFs) requires a census of their occurrence and properties. We perform a systematic search of GMFs in the fourth Galactic quadrant and determine their basic physical properties. We perform a systematic search of GMFs in the fourth Galactic quadrant and determine their basic physical properties. Methods. We identify GMFs based on their dust extinction signatures in the near- and mid-infrared and the velocity structure probed by ^13^CO line emission. We use the ^13^CO line emission and ATLASGAL dust emission data to estimate the total and dense gas masses of the GMFs. We combine our sample with an earlier sample from literature and study the Galactic environment of the GMFs.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A11
- Title:
- G35.20-0.74N continuum and line data cubes
- Short Name:
- J/A+A/569/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation process of high-mass stars (with masses >8M_{sun}_) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. The advent of the Atacama Large Millimeter Array (ALMA) is expected to provide observational evidence to better constrain the theoretical scenarios. The present study aims at characterizing the high-mass star forming region G35.20-0.74N, which is found associated with at least one massive outflow and contains multiple dense cores, one of them recently found associated with a Keplerian rotating disk. We used the radio-interferometer ALMA to observe the G35.20-0.74N region in the submillimeter continuum and line emission at 350GHz. The observed frequency range covers tracers of dense gas (e.g., H^13^CO^+^, C^17^O), molecular outflows (e.g., SiO), and hot cores (e.g., CH_3_CN, CH_3_OH). These observations were complemented with infrared and centimeter data.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/33
- Title:
- GOBELINS. IV. VLBA obs. of Taurus
- Short Name:
- J/ApJ/859/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new trigonometric parallaxes and proper motions of young stellar objects in the Taurus molecular cloud complex from observations collected with the Very Long Baseline Array as part of the Gould's Belt Distances Survey. We detected 26 young stellar objects and derived trigonometric parallaxes for 18 stars with an accuracy of 0.3% to a few percent. We modeled the orbits of six binaries and determined the dynamical masses of the individual components in four of these systems (V1023 Tau, T Tau S, V807 Tau, and V1000 Tau). Our results are consistent with the first trigonometric parallaxes delivered by the Gaia satellite and reveal the existence of significant depth effects. We find that the central portion of the dark cloud Lynds 1495 is located at d=129.5+/-0.3pc, while the B216 clump in the filamentary structure connected to it is at d=158.1+/-1.2pc. The closest and remotest stars in our sample are located at d=126.6+/-1.7pc and d=162.7+/-0.8pc, yielding a distance difference of about 36pc. We also provide a new distance estimate for HL Tau that was recently imaged. Finally, we compute the spatial velocity of the stars with published radial velocity and investigate the kinematic properties of the various clouds and gas structures in this region.
- ID:
- ivo://CDS.VizieR/J/ApJ/801/91
- Title:
- Gould's Belt Very Large Array survey. IV. Taurus
- Short Name:
- J/ApJ/801/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-epoch radio study of the Taurus-Auriga star-forming complex made with the Karl G. Jansky Very Large Array at frequencies of 4.5GHz and 7.5GHz. We detect a total of 610 sources, 59 of which are related to young stellar objects (YSOs) and 18 to field stars. The properties of 56% of the young stars are compatible with non-thermal radio emission. We also show that the radio emission of more evolved YSOs tends to be more non-thermal in origin and, in general, that their radio properties are compatible with those found in other star-forming regions. By comparing our results with previously reported X-ray observations, we notice that YSOs in Taurus-Auriga follow a Gudel-Benz relation with {kappa}=0.03, as we previously suggested for other regions of star formation. In general, YSOs in Taurus-Auriga and in all the previous studied regions seem to follow this relation with a dispersion of ~1dex. Finally, we propose that most of the remaining sources are related with extragalactic objects but provide a list of 46 unidentified radio sources whose radio properties are compatible with a YSO nature.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/49
- Title:
- Gould's Belt VLA survey. III. Orion region
- Short Name:
- J/ApJ/790/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a high-sensitivity (60{mu}Jy), large-scale (2.26deg^2^) survey obtained with the Karl G. Jansky Very Large Array as part of the Gould's Belt Survey program. We detected 374 and 354 sources at 4.5 and 7.5GHz, respectively. Of these, 148 are associated with previously known young stellar objects (YSOs). Another 86 sources previously unclassified at either optical or infrared wavelengths exhibit radio properties that are consistent with those of young stars. The overall properties of our sources at radio wavelengths such as their variability and radio to X-ray luminosity relation are consistent with previous results from the Gould's Belt Survey. Our detections provide target lists for follow-up Very Long Baseline Array radio observations to determine their distances as YSOs are located in regions of high nebulosity and extinction, making it difficult to measure optical parallaxes.
- ID:
- ivo://CDS.VizieR/J/ApJ/805/9
- Title:
- Gould's Belt VLA Survey. II. Serpens region
- Short Name:
- J/ApJ/805/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep (~17{mu}Jy) radio continuum observations of the Serpens molecular cloud, the Serpens south cluster, and the W40 region obtained using the Very Large Array in its A configuration. We detect a total of 146 sources, 29 of which are young stellar objects (YSOs), 2 of which are BV stars, and 5 more of which are associated with phenomena related to YSOs. Based on their radio variability and spectral index, we propose that about 16 of the remaining 110 unclassified sources are also YSOs. For approximately 65% of the known YSOs detected here as radio sources, the emission is most likely non-thermal and related to stellar coronal activity. As also recently observed in Ophiuchus, our sample of YSOs with X-ray counterparts lies below the fiducial Guedel & Benz (1993ApJ...405L..63G) relation. Finally, we analyze the proper motions of nine sources in the W40 region. This allows us to better constrain the membership of the radio sources in the region.
- ID:
- ivo://CDS.VizieR/J/ApJ/775/63
- Title:
- Gould's Belt VLA Survey. I. Ophiuchus complex
- Short Name:
- J/ApJ/775/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present large-scale (~2000arcmin^2^), deep (~20{mu}Jy), high-resolution (~1") radio observations of the Ophiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array at {lambda}=4 and 6cm. In total, 189 sources were detected, 56 of them associated with known young stellar sources, and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although we also detect four objects of A/F/B types and two brown dwarf candidates. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronas characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a Gudel-Benz relation, but with a different normalization than the most radioactive types of stars. Finally, we detect a ~70mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region.
