- ID:
- ivo://CDS.VizieR/J/AJ/120/2638
- Title:
- CCD speckle obs. of binary stars. II.
- Short Name:
- J/AJ/120/2638
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Speckle observations of 145 double stars and suspected double stars are presented and discussed. On the basis of multiple observations, a total of 280 position angle and separation measures are determined, as well as 23 high-quality nondetections. All observations were taken with the (unintensified) Rochester Institute of Technology fast-readout CCD camera mounted on the Lowell-Tololo 61 cm telescope at the Cerro Tololo Inter-American Observatory during 1999 October. We find that the measures, when judged as a whole against ephemeris positions of binaries with very well-known orbits, have root mean square deviations of 18+/-03{deg} in position angle and 13+/-2mas in separation. Eleven double stars discovered by Hipparcos were also successfully observed, and the change in position angle and/or separation since the Hipparcos observations was substantial in three cases.
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- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/431/773
- Title:
- CHARM2, an updated of CHARM catalog
- Short Name:
- J/A+A/431/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update of the Catalog of High Angular Resolution Measurements (CHARM, Richichi & Percheron, 2002, Cat. <J/A+A/386/492>), which includes results available until July 2004. CHARM2 is a compilation of direct measurements by high angular resolution methods, as well as indirect estimates of stellar diameters. Its main goal is to provide a reference list of sources which can be used for calibration and verification observations with long-baseline optical and near-IR interferometers. Single and binary stars are included, as are complex objects from circumstellar shells to extragalactic sources. The present update provides an increase of almost a factor of two over the previous edition. Additionally, it includes several corrections and improvements, as well as a cross-check with the valuable public release observations of the ESO Very Large Telescope Interferometer (VLTI). A total of 8231 entries for 3238 unique sources are now present in CHARM2. This represents an increase of a factor of 3.4 and 2.0, respectively, over the contents of the previous version of CHARM.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/1615
- Title:
- CH_3_OH maser survey of EGOs
- Short Name:
- J/ApJ/702/1615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a high angular resolution Very Large Array (VLA) Class I 44GHz and Class II 6.7GHz CH_3_OH maser survey of a sample of ~20 massive young stellar object (MYSO) outflow candidates selected on the basis of extended 4.5um emission in Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire images. These 4.5um selected candidates are referred to as extended green objects (EGOs), for the common coding of this band as green in three-color Infrared Array Camera images. The detection rate of 6.7GHz Class II CH_3_OH masers, which are associated exclusively with massive YSOs, toward EGOs is >~64% - nearly double the detection rate of surveys using other MYSO selection criteria. The detection rate of Class I 44GHz CH_3_OH masers, which trace molecular outflows, is ~89% toward EGOs associated with 6.7GHz CH_3_OH masers.
- ID:
- ivo://CDS.VizieR/J/A+A/639/L13
- Title:
- 4C 41.17 IRAM/NOEMA data cubes
- Short Name:
- J/A+A/639/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new, spatially resolved [CI]1-0, [CI]2-1, CO(7-6), and dust continuum observations of 4C 41.17 at z=3.8. This is one of the best-studied radio galaxies in this epoch and is arguably the best candidate of jet-triggered star formation at high redshift currently known in the literature. 4C 41.17 shows a narrow ridge of dust continuum extending over 15kpc near the radio jet axis. Line emission is found within the galaxy in the region with signatures of positive feedback. Using the [CI]1-0 line as a molecular gas tracer, and multifrequency observations of the far-infrared dust heated by star formation, we find a total gas mass of 7.6x10^10^M_{sun}_, which is somewhat greater than that previously found from CO(4-3). The gas mass surface density of 10^3^M_{sun}_/yr/pc^2^ and the star formation rate surface density of 10M_{sun}_/yr/kpc^2^ were derived over the 12 kpc8 kpc area, where signatures of positive feedback have previously been found. These densities are comparable to those in other populations of massive, dusty star-forming galaxies in this redshift range, suggesting that the jet does not currently enhance the efficiency with which stars form from the gas. This is consistent with expectations from simulations, whereby radio jets may facilitate the onset of star formation in galaxies without boosting its efficiency over longer timescales, in particular after the jet has broken out of the interstellar medium, as is the case in 4C 41.17. The release includes Gaussian line fits to the [CI]1-0, [CI]2-1, and CO(7-6) emission lines in the radio galaxy 4C 41.17 at z=3.8, as well as the interferometric data cubes.
- ID:
- ivo://CDS.VizieR/J/ApJ/734/67
- Title:
- Circumstellar emission measures with Keck
- Short Name:
- J/ApJ/734/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Keck Interferometer Nuller (KIN) was used to survey 25 nearby main-sequence stars in the mid-infrared, in order to assess the prevalence of warm circumstellar (exozodiacal) dust around nearby solar-type stars. The KIN measures circumstellar emission by spatially blocking the star but transmitting the circumstellar flux in a region typically 0.1-4AU from the star. We find one significant detection ({eta} Crv), two marginal detections ({gamma} Oph and {alpha} Aql), and 22 clear non-detections. Using a model of our own solar system's zodiacal cloud, scaled to the luminosity of each target star, we estimate the equivalent number of target zodis needed to match our observations. Our three zodi detections are {eta} Crv (1250+/-260), {gamma} Oph (200+/-80), and {alpha} Aql (600+/-200), where the uncertainties are 1{sigma}. The 22 non-detected targets have an ensemble weighted average consistent with zero, with an average individual uncertainty of 160 zodis (1{sigma}). These measurements represent the best limits to date on exozodi levels for a sample of nearby main-sequence stars. A statistical analysis of the population of 23 stars not previously known to contain circumstellar dust (excluding {eta} Crv and {gamma} Oph) suggests that, if the measurement errors are uncorrelated (for which we provide evidence) and if these 23 stars are representative of a single class with respect to the level of exozodi brightness, the mean exozodi level for the class is <150 zodis (3{sigma} upper limit, corresponding to 99% confidence under the additional assumption that the measurement errors are Gaussian). We also demonstrate that this conclusion is largely independent of the shape and mean level of the (unknown) true underlying exozodi distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A33
- Title:
- Class 0 sources continuum subtracted UV-tables
- Short Name:
- J/A+A/590/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300AU is still poorly constrained. While molecular line observations demonstrate the presence of disks with Keplerian rotation toward a handful of sources, others show no hints of rotation. Determining the structure on small scales (few 100AU) is crucial for understanding the physical and chemical evolution from cores to disks. To determine the presence and characteristics of compact, disk-like structures in deeply-embedded low-mass protostars. A related goal is to investigate how the derived structure affects the determination of gas-phase molecular abundances on hot-core scales. Two models of the emission, a Gaussian disk intensity distribution and a parametrized power-law disk model, are fitted to sub-arcsecond resolution interferometric continuum observations of five Class 0 sources, including one source with a confirmed Keplerian disk. Prior to fitting the models to the de-projected real visibilities, the estimated envelope from an independent model and any companion source are subtracted. For reference, a spherically symmetric single power-law envelope is fitted to the larger scale (~1000AU) emission and investigated further for one of the sources on smaller scales.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/127
- Title:
- CLASSy: CARMA obs. in L1451 region of Perseus
- Short Name:
- J/ApJ/830/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 3mm spectral line and continuum survey of L1451 in the Perseus Molecular Cloud. These observations are from the CARMA Large Area Star Formation Survey (CLASSy), which also imaged Barnard 1, NGC1333, Serpens Main, and Serpens South. L1451 is the survey region with the lowest level of star formation activity-it contains no confirmed protostars. HCO^+^, HCN, and N_2_H^+^ (J=1->0) are all detected throughout the region, with HCO^+^ being the most spatially widespread, and molecular emission seen toward 90% of the area above N(H_2_) column densities of 1.9x10^21^cm^-2^. HCO^+^ has the broadest velocity dispersion, near 0.3km/s on average, compared with ~0.15km/s for the other molecules, thus representing a range of subsonic to supersonic gas motions. Our non-binary dendrogram analysis reveals that the dense gas traced by each molecule has a similar hierarchical structure, and that gas surrounding the candidate first hydrostatic core (FHSC), L1451-mm, and other previously detected single-dish continuum clumps has similar hierarchical structure; this suggests that different subregions of L1451 are fragmenting on the pathway to forming young stars. We determined that the three-dimensional morphology of the largest detectable dense-gas structures was relatively ellipsoidal compared with other CLASSy regions, which appeared more flattened at the largest scales. A virial analysis shows that the most centrally condensed dust structures are likely unstable against collapse. Additionally, we identify a new spherical, centrally condensed N_2_H^+^ feature that could be a new FHSC candidate. The overall results suggest that L1451 is a young region starting to form its generation of stars within turbulent, hierarchical structures.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/25
- Title:
- 6 & 1.3cm deep VLA obs. toward 58 high-mass SFRs
- Short Name:
- J/ApJS/227/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-sensitivity radio continuum survey at 6 and 1.3cm using the Karl G. Jansky Very Large Array toward a sample of 58 high-mass star-forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC-IRs and CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the 1mJy level. Due to the improvement in the continuum sensitivity of the Very Large Array, this survey achieved map rms levels of ~3-10{mu}Jy/beam at sub-arcsecond angular resolution. We extracted 70 continuum sources associated with 1.2mm dust clumps. Most sources are weak, compact, and prime candidates for high-mass protostars. Detection rates of radio sources associated with the millimeter dust clumps for CMCs, CMC-IRs, and HMCs are 6%, 53%, and 100%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC-IRs occur close to the dust clump centers, with a median offset from it of 12000au and 4000au, respectively. We calculated 5-25GHz spectral indices using power-law fits and obtained a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A155
- Title:
- CO+[CI] emission in distant galaxies
- Short Name:
- J/A+A/641/A155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of multiple carbon monoxide CO line transitions with ALMA in a few tens of infrared-selected galaxies on and above the main sequence at z=1.1-1.7. We reliably detected the emission of CO(5-4), CO(2-1), and CO(7-6)+[CI](2-1) in 50, 33, and 13 galaxies, respectively, and we complemented this information with available CO(4-3) and [CI](1-0) fluxes for part of the sample, and by modeling of the optical-to-millimeter spectral energy distribution. We retrieve a quasi-linear relation between LIR and CO(5-4) or CO(7-6) for main-sequence galaxies and starbursts, corroborating the hypothesis that these transitions can be used as star formation rate (SFR) tracers. We find the CO excitation to steadily increase as a function of the star formation efficiency (SFE), the mean intensity of the radiation field warming the dust (<U>), the surface density of SFR (SigmaSFR), and, less distinctly, with the distance from the main sequence. This adds to the tentative evidence for higher excitation of the CO+[CI] spectral line energy distribution (SLED) of starburst galaxies relative to that for main-sequence objects, where the dust opacities play a minor role in shaping the high-J CO transitions in our sample. However, the distinction between the average SLED of upper main-sequence and starburst galaxies is blurred, driven by a wide variety of intrinsic shapes. Large velocity gradient radiative transfer modeling demonstrates the existence of a highly excited component that elevates the CO SLED of high-redshift main-sequence and starbursting galaxies above the typical values observed in the disk of the Milky Way. This excited component is dense and it encloses ~50% of the total molecular gas mass in main-sequence objects. We interpret the observed trends involving the CO excitation as to be mainly determined by a combination of large SFRs and compact sizes, as a large SigmaSFR is naturally connected with enhanced dense molecular gas fractions and higher dust and gas temperatures, due to increasing ultraviolet radiation fields, cosmic ray rates, as well as dust and gas coupling. We release the full data compilation and the ancillary information to the community.
