- ID:
- ivo://CDS.VizieR/J/A+A/564/A99
- Title:
- Chamaeleon-MMS1 NH_3_ (1,1) and (2,2) maps
- Short Name:
- J/A+A/564/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this study is to investigate the structure and kinematics of the nearby candidate first hydrostatic core Cha-MMS1. Cha-MMS1 was mapped in the NH_3_(1,1) line and the 1.2cm continuum using the Australia Telescope Compact Array, ATCA. The angular resolution of the ATCA observations is 7" (~1000AU), and the velocity resolution is 50m/s. The core was also mapped with the 64-m Parkes telescope in the NH_3_(1,1) and (2,2) lines. Observations from Herschel Space Observatory and Spitzer Space telescope were used to help interpretation. The ammonia spectra were analysed using Gaussian fits to the hyperfine structure. A two-layer model was applied in the central parts of the core where the ATCA spectra show signs of self-absorption.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/633/A126
- Title:
- Cha-MMS1 CO 3-2 and ^13^CO 3-2 datacubes
- Short Name:
- J/A+A/633/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of its low luminosity, its chemical composition, and the absence of a large-scale outflow, the dense core Cha-MMS1 located in the Chamaeleon I molecular cloud was proposed as a first hydrostatic core (FHSC) candidate a decade ago. Our goal is to test this hypothesis by searching for a slow, compact outflow driven by Cha-MMS1 that would match the predictions of MHD simulations for this short phase of star formation. We use the Atacama Large Millimeter/submillimeter Array (ALMA) to map Cha-MMS1 at high angular resolution in CO 3-2 and ^13^CO 3-2 as well as in continuum emission. We report the detection of a bipolar outflow emanating from the central core, along a (projected) direction roughly parallel to the filament in which Cha-MMS1 is embedded and perpendicular to the large-scale magnetic field. The morphology of the outflow indicates that its axis lies close to the plane of the sky. We measure velocities corrected for inclination of more than 90km/s which is clearly incompatible with the expected properties of a FHSC outflow. Several properties of the outflow are determined and compared to previous studies of Class 0 and Class I protostars. The outflow of Cha-MMS1 has a much smaller momentum force than the outflows of other Class0 protostars. In addition, we find a dynamical age of 200-3000yr indicating that Cha-MMS1 might be one of the youngest ever observed Class 0 protostars. While the existence of the outflow suggests the presence of a disk, no disk is detected in continuum emission and we derive an upper limit of 55au to its radius. We conclude that Cha-MMS1 has already gone through the FHSC phase and is a young Class 0 protostar, but it has not brought its outflow to full power yet.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/118
- Title:
- Chandra and IR study toward IRAS 16562-3959
- Short Name:
- J/ApJ/888/118
- Date:
- 17 Jan 2022 11:46:14
- Publisher:
- CDS
- Description:
- We present the results from Chandra X-ray observations, and near- and mid-infrared analysis, using VISTA/VVV and Spitzer/GLIMPSE catalogs, of the high-mass star-forming region IRAS 16562-3959, which contains a candidate for a high-mass protostar. We detected 249 X-ray sources within the ACIS-I field of view. The majority of the X-ray sources have low count rates (<0.638cts/ks) and hard X-ray spectra. The search for YSOs in the region using VISTA/VVV and Spitzer/GLIMPSE catalogs resulted in a total of 636 YSOs, with 74 Class I and 562 Class II YSOs. The search for near- and mid-infrared counterparts of the X-ray sources led to a total of 165 VISTA/VVV counterparts, and a total of 151 Spitzer/GLIMPSE counterparts. The infrared analysis of the X-ray counterparts allowed us to identify an extra 91 Class III YSOs associated with the region. We conclude that a total of 727 YSOs are associated with the region, with 74 Class I, 562 Class II, and 91 Class III YSOs. We also found that the region is composed of 16 subclusters. In the vicinity of the high-mass protostar, the stellar distribution has a core-halo structure. The subcluster containing the high-mass protostar is the densest and the youngest in the region, and the high-mass protostar is located at its center. The YSOs in this cluster appear to be substantially older than the high-mass protostar.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/2
- Title:
- Chandra Carina Complex Project (CCCP) catalog
- Short Name:
- J/ApJS/194/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of ~14000 X-ray sources observed by the ACIS instrument on the Chandra X-ray Observatory within a 1.42deg^2^ survey of the Great Nebula in Carina, known as the Chandra Carina Complex Project (CCCP). This study appears in a special issue devoted to the CCCP. Here, we describe the data reduction and analysis procedures performed on the X-ray observations, including calibration and cleaning of the X-ray event data, point-source detection, and source extraction. The catalog appears to be complete across most of the field to an absorption-corrected total-band luminosity of ~10^30.7^erg/s for a typical low-mass pre-main-sequence star. Counterparts to the X-ray sources are identified in a variety of visual, near-infrared, and mid-infrared surveys. The X-ray and infrared source properties presented here form the basis of many CCCP studies of the young stellar populations in Carina.
- ID:
- ivo://CDS.VizieR/J/PASJ/55/635
- Title:
- Chandra observations of Monoceros R2
- Short Name:
- J/PASJ/55/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of the Chandra ACIS-I observation on the central region of the Monoceros R2 cloud (Mon R2), a high-mass star-forming region (SFR) at a distance of 830pc. With a deep exposure of ~100ks, we detected 368 X-ray sources, ~80% of which were identified with the near-infrared (NIR) counterparts. We systematically analyzed the spectra and time variability of most of the X-ray emitting sources and provided a comprehensive X-ray source catalog for the first time. Using the J-, H- and K-bands magnitudes of the NIR counterparts, we estimated the evolutionary phase (classical T Tauri stars and weak-lined T Tauri stars) and the mass of the X-ray emitting sources, and analyzed the X-ray properties as a function of the age and mass.
- ID:
- ivo://CDS.VizieR/J/A+A/463/275
- Title:
- Chandra obs. of Serpens star-forming region
- Short Name:
- J/A+A/463/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study the properties of X-ray emission from young stellar objects (YSOs) through their evolution from Class I to Class III and determine whether Class 0 protostars emit X-rays. A deep Chandra X-ray observation of the Serpens star-forming region was obtained. The Serpens Cloud Core is ideally suited for this type of investigation, being populated by a dense and extremely young cluster whose members are found in all evolutionary stages, including six well-studied Class 0 sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/696/47
- Title:
- Chandra study of Rosette star-forming complex. II.
- Short Name:
- J/ApJ/696/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore here the young stellar populations in the Rosette Molecular Cloud (RMC) region with high spatial resolution X-ray images from the Chandra X-ray Observatory, which are effective in locating weak-lined T Tauri stars as well as disk-bearing young stars. A total of 395 X-ray point sources are detected, 299 of which (76%) have an optical or near-infrared (NIR) counterpart identified from deep FLAMINGOS images. From X-ray and mass sensitivity limits, we infer a total population of ~1700 young stars in the survey region. Based on smoothed stellar surface density maps, we investigate the spatial distribution of the X-ray sources and define three distinctive structures and substructures within them. Structures B and C are associated with previously known embedded IR clusters, while structure A is a new X-ray-identified unobscured cluster. A high-mass protostar RMCX 89=IRAS 06306+0437 and its associated sparse cluster are studied.
- ID:
- ivo://CDS.VizieR/J/AJ/155/241
- Title:
- Chandra X-ray detection of YSOs in Serpens South
- Short Name:
- J/AJ/155/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Chandra study of the deeply embedded Serpens South star-forming region, examining cluster structure and disk properties at the earliest stages. In total, 152 X-ray sources are detected. Combined with Spitzer and 2MASS photometry, 66 X-ray sources are reliably matched to an IR counterpart. We identify 21 class I, 6 flat spectrum, 16 class II, and 18 class III young stars; 5 were unclassified. Eighteen sources were variable in X-rays, 8 exhibiting flare-like emission and one source being periodic. The cluster's X-ray luminosity distance was estimated: the best match was to the nearer distance of 260 pc for the front of the Aquila Rift complex. The ratio of N_H_ to A_K_ is found to be ~0.68x10^22^, similar to that measured in other young low-mass regions, but lower than that measured in the interstellar medium and high-mass clusters (~(1.6-2)x10^22^). We find that the spatial distribution closely follows that of the dense filament from which the stars have formed, with the class II population still strongly associated with the filament. There are four subclusters in the field, with three forming knots in the filament, and a fourth to the west, which may not be associated but may be contributing to the distributed class III population. A high percentage of diskless class IIIs (upper limit 30% of classified X-ray sources) in such a young cluster could indicate that processing of disks is influenced by the cluster environment and is not solely dependent on timescale.
- ID:
- ivo://CDS.VizieR/J/PASJ/55/653
- Title:
- Chandra X-ray flares in rho Ophiuchi
- Short Name:
- J/PASJ/55/653
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of a systematic study of X-ray flares from low-mass young stellar objects, using two deep exposure Chandra observations of the main region of the {rho} Ophiuchi star-forming cloud. From 195 X-ray sources, including class I-III sources and some young brown dwarfs, we detected a total of 71 X-ray flares.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/71
- Title:
- CHARA array obs. of 13 AB Dor moving group stars
- Short Name:
- J/ApJ/858/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interferometric measurements obtained with the CHARA Array of 13 adolescent-age stars in nearby moving groups. The motivation was to spatially resolve the largest stars and to search for binary companions. Nine stars have diameters smaller than the resolution limit and no evidence for companions within 0.5-50mas and {Delta}H<2.0mag. The diameters of three stars were spatially resolved: GJ 159 (0.582+/-0.016mas) and GJ 393 (0.564+/-0.021mas) in the AB Dor moving group, and former member HD 89744 (0.556+/-0.032mas). Combining the angular diameters with their distances and bolometric fluxes, we measured radii and effective temperatures. The temperatures of GJ 159 (6286+/-123K) and GJ 393 (3515+/-68K) are consistent with spectroscopic measurements. Comparisons with evolutionary models show that HD 89744 has evolved off the main sequence. GJ 159 and GJ 393 lie within 1.5{sigma} of the zero-age main sequence, complicating their age estimates because it is unclear whether the stars are contracting or expanding. GJ 159 has a mass of 1.2+/-0.1M_{sun}_ with an age spanning 0.021-3.0Gyr. Its debris disk and lithium abundance favor a young age. GJ 393 has a mass of 0.42+/-0.03M_{sun}_ and a lower limit on its age 0.06Gyr. This overlaps with the age of the moving group; however, an older age would be more consistent with its slow rotation, low activity, and luminosity, suggesting that GJ 393 is a kinematic interloper.
