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- ID:
- ivo://CDS.VizieR/J/ApJ/757/112
- Title:
- Stellar diameters. II. K and M-stars
- Short Name:
- J/ApJ/757/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33 K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for ~K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B-V), (V-R), (V-I), (V-J), (V-H), and (V-K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H]=-0.5 to +0.1dex and are accurate to ~2%, ~5%, and ~4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A32
- Title:
- Sub-mm images of SSTB213 J041757.75+274105.5
- Short Name:
- J/A+A/564/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the proto brown dwarf candidate SSTB213 J041757 with the Submillimeter Array to search for CO molecular outflow emission from the source. Our CO maps do not show any outflow emission from the proto brown dwarf candidate. The non-detection implies that the molecular outflows from the source are weak; deeper observations are therefore needed to probe the outflows from the source.
- ID:
- ivo://CDS.VizieR/J/ApJ/837/139
- Title:
- SUPER GOODS. I. Ultradeep SCUBA-2 survey
- Short Name:
- J/ApJ/837/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this first paper in the SUPER GOODS series on powerfully star-forming galaxies in the two GOODS fields, we present a deep SCUBA-2 survey of the GOODS-N at both 850 and 450{mu}m (central rms noise of 0.28mJy and 2.6mJy, respectively). In the central region, the 850{mu}m observations cover the GOODS-N to near the confusion limit of ~1.65mJy, while over a wider 450arcmin^2^ region-well complemented by Herschel far-infrared imaging-they have a median 4{sigma} limit of 3.5mJy. We present >=4{sigma} catalogs of 186 850{mu}m and 31 450{mu}m selected sources. We use interferometric observations from the Submillimeter Array (SMA) and the Karl G. Jansky Very Large Array (VLA) to obtain precise positions for 114 SCUBA-2 sources (28 from the SMA, all of which are also VLA sources). We present new spectroscopic redshifts and include all existing spectroscopic or photometric redshifts. We also compare redshifts estimated using the 20cm/850{mu}m and the 250cm/850{mu}m flux ratios. We show that the redshift distribution increases with increasing flux, and we parameterize the dependence. We compute the star formation history and the star formation rate (SFR) density distribution functions in various redshift intervals, finding that they reach a peak at z=2-3 before dropping to higher redshifts. We show that the number density per unit volume of SFR>~500M_{sun}_/yr galaxies measured from the SCUBA-2 sample does not change much relative to that of lower SFR galaxies from UV selected samples over z=2-5, suggesting that, apart from changes in the normalization, the shape in the number density as a function of SFR is invariant over this redshift interval.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/158
- Title:
- Survey of Class II sources in Taurus with ALMA
- Short Name:
- J/ApJ/872/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a survey of young single and multiple systems in the Taurus-Auriga star-forming region with the Atacama Large Millimeter Array (ALMA), substantially improving both the spatial resolution and sensitivity with which individual protoplanetary disks in these systems have been observed. These ALMA observations can resolve binary separations as small as 25-30au and have an average 3{sigma} detection level of 0.35mJy, equivalent to a disk mass of 4x10^-5^M_{sun}_ for an M3 star. Our sample was constructed from stars that have an infrared excess and/or signs of accretion and have been classified as Class II. For the binary and higher-order multiple systems observed, we detect {lambda}=1.3mm continuum emission from one or more stars in all of our target systems. Combined with previous surveys of Taurus, our 21 new detections increase the fraction of millimeter-detected disks to over 75% in all categories of stars (singles, primaries, and companions) earlier than spectral type M6 in the Class II sample. Given the wealth of other information available for these stars, this has allowed us to study the impact of multiplicity with a much larger sample. While millimeter flux and disk mass are related to stellar mass as seen in previous studies, we find that both primary and secondary stars in binary systems with separations of 30-4200au have lower values of millimeter flux as a function of stellar mass than single stars. We also find that for these systems, the circumstellar disk around the primary star does not dominate the total disk mass in the system and contains on average 62% of the total mass.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A52
- Title:
- SVS13-A Class I IRAM-NOEMA images
- Short Name:
- J/A+A/654/A52
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Recent results in astrochemistry have revealed that some molecules, such as interstellar complex organic species and deuterated species, can serve as valuable tools in the investigation of star-forming regions. Sulphuretted species can also be used to follow the chemical evolution of the early stages of a Sun-like star formation process. The goal is to obtain a census of S-bearing species using interferometric images towards SVS13-A, a Class I object associated with a hot corino that is rich in interstellar complex organic molecules. To this end, we used the NGC1333 SVS13-A data at 3mm and 1.4mm obtained with the IRAM-NOEMA interferometer in the framework of the SOLIS (Seeds of Life in Space) Large Program. The line emission of S-bearing species was imaged and analyzed using local thermodynamic equilibrium (LTE) and large velocity gradient (LVG) approaches. We imaged the spatial distribution on <=300au scale of the line emission of ^32^SO, ^34^SO, C^32^S, C^34^S, C^33^S, OCS, H_2_C^32^S, H_2_C^34^S, and NS. The low excitation (9K) ^32^SO line traces: (i) the low-velocity SVS13-A outflow and (ii) the fast (up to 100km/s away from the systemic velocity) collimated jet driven by the nearby SVS13-B Class 0 object. Conversely, the rest of the lines are confined in the inner SVS13-A region, where complex organics were previously imaged.More specifically, the non-LTE LVG analysis of SO, SO_2_, and H_2_CS indicates a hot corino origin (size in the 60-120au range). Temperatures between 50K and 300K, as well as volume densities larger than 10^5^cm^-3^ have been derived. The abundances of the sulphuretted are in the following ranges: 0.3-6x10^-6^ (CS), 7x10^-9^-1x10^-7^ (SO), 1-10x10^-7^ (SO_2_), a few 10^-10^ (H_2_CS and OCS), and 10^-10^-10^-9^ (NS). The N(NS)/N(NS+) ratio is larger than 10, supporting the assessment that the NS+ ion is mainly formed in the extended envelope. The [H_2_CS]/[H_2_CO] ratio, once measured at high-spatial resolutions, increases with time (from Class 0 to Class II objects) by more than one order of magnitude (from <=10^-2^ to a few 10^-1^). This suggests that [S]/[O] changes along the process of Sun-like star formation. Finally, the estimate of the [S]/[H] budget in SVS13-A is 2%-17% of the Solar System value (1.8x10^-5^), which is consistent with what was previously measured towards Class 0 objects (1%-8%). This finding supports the notion that the enrichment of the sulphuretted species with respect to dark clouds remains constant from the Class 0 to the Class I stages of lowmass star formation. The present findings stress the importance of investigating the chemistry of star-forming regions using large observational surveys as well as sampling regions on the scale of the Solar System.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/27
- Title:
- The ATLBS Extended Source Sample
- Short Name:
- J/ApJS/199/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the Australia Telescope Low Brightness Survey (ATLBS) we present a sample of extended radio sources and derive morphological properties of faint radio sources. One hundred nineteen radio galaxies form the ATLBS Extended Source Sample (ATLBS-ESS) consisting of all sources exceeding 30" in extent and integrated flux densities exceeding 1mJy. We give structural details along with information on galaxy identifications and source classifications. The ATLBS-ESS, unlike samples with higher flux-density limits, has almost equal fractions of FR-I and FR-II radio galaxies, with a large fraction of the FR-I population exhibiting 3C31-type structures. Significant asymmetry in lobe extents appears to be a common occurrence in the ATLBS-ESS FR-I sources compared with FR-II sources. We present a sample of 22 FR-Is at z>0.5 with good structural information. The detection of several giant radio sources, with size exceeding 0.7Mpc, at z>1 suggests that giant radio sources are not less common at high redshifts. The ESS also includes a sample of 28 restarted radio galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1646
- Title:
- The Galactic Center region at 330MHz
- Short Name:
- J/AJ/128/1646
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a wide-field, subarcminute-resolution VLA image of the Galactic center region at 330MHz. With a resolution of ~7"x12" and an rms noise of 1.6mJy/beam, this image represents a significant increase in resolution and sensitivity over the previously published VLA image at this frequency. The improved sensitivity has more than tripled the census of small-diameter sources in the region, has resulted in the detection of two new nonthermal filaments (NTFs), 18 NTF candidates, and 30 pulsar candidates, reveals previously known extended sources in greater detail, and has resulted in the first detection of Sagittarius A* in this frequency range.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/4048
- Title:
- The H{alpha} rotation curve of M33
- Short Name:
- J/MNRAS/449/4048
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a long-term project to revisit the kinematics and dynamics of the large disc galaxies of the Local Group, we present the first deep, wide-field (~42arcmin x 56arcmin) 3D-spectroscopic survey of the ionized gas disc of Messier 33. Fabry-Perot interferometry has been used to map its H{alpha} distribution and kinematics at unprecedented angular resolution (~<3 arcsec) and resolving power (~12600), with the 1.6 m telescope at the Observatoire du Mont Megantic. The ionized gas distribution follows a complex, large-scale spiral structure, unsurprisingly coincident with the already-known spiral structures of the neutral and molecular gas discs. The kinematical analysis of the velocity field shows that the rotation centre of the H{alpha} disc is distant from the photometric centre by ~168 pc (sky-projected distance) and that the kinematical major-axis position angle and disc inclination are in excellent agreement with photometric values. The H{alpha} rotation curve agrees very well with the HI rotation curves for 0<R<6.5 kpc, but the H{alpha} velocities are 10^-20^ km/s higher for R>6.5 kpc. The reason for this discrepancy is not well understood. The velocity dispersion profile is relatively flat around 16 km/s, which is at the low end of velocity dispersions of nearby star-forming galactic discs. A strong relation is also found between the H{alpha} velocity dispersion and the H{alpha} intensity. Mass models were obtained using the H{alpha} rotation curve but, as expected, the dark matter halo's parameters are not very well constrained since the optical rotation curve only extends out to 8 kpc.
- ID:
- ivo://CDS.VizieR/J/AJ/156/286
- Title:
- The LEECH exoplanet imaging survey
- Short Name:
- J/AJ/156/286
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the largest L' (3.8 {mu}m) direct imaging survey for exoplanets to date, the Large Binocular Telescope Interferometer Exozodi Exoplanet Common Hunt (LEECH). We observed 98 stars with spectral types from B to M. Cool planets emit a larger share of their flux in L' compared to shorter wavelengths, affording LEECH an advantage in detecting low-mass, old, and cold-start giant planets. We emphasize proximity over youth in our target selection, probing physical separations smaller than other direct imaging surveys. For FGK stars, LEECH outperforms many previous studies, placing tighter constraints on the hot-start planet occurrence frequency interior to ~20 au. For less luminous, cold-start planets, LEECH provides the best constraints on giant-planet frequency interior to ~20 au around FGK stars. Direct imaging survey results depend sensitively on both the choice of evolutionary model (e.g., hot- or cold-start) and assumptions (explicit or implicit) about the shape of the underlying planet distribution, in particular its radial extent. Artificially low limits on the planet occurrence frequency can be derived when the shape of the planet distribution is assumed to extend to very large separations, well beyond typical protoplanetary dust-disk radii (~<50 au), and when hot-start models are used exclusively. We place a conservative upper limit on the planet occurrence frequency using cold-start models and planetary population distributions that do not extend beyond typical protoplanetary dust-disk radii. We find that ~<90% of FGK systems can host a 7-10 M_Jup_ planet from 5 to 50 au. This limit leaves open the possibility that planets in this range are common.
