- ID:
- ivo://CDS.VizieR/J/ApJ/771/129
- Title:
- Submillimetric Class II sources of Taurus
- Short Name:
- J/ApJ/771/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new "snapshot" {lambda}=1.3mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f(L_mm_), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3{sigma} depth of roughly 3mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L_mm_ and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L_mm_ and the disk mass, M_d_, we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3mm flux density of ~25mJy for 1M_{sun}_ hosts and a power-law scaling L_mm_{propto}M_{star}_^1.5-2.0^. We suggest that a reasonable treatment of dust temperature in the conversion from L_mm_ to M_d_ favors an inherently linear M_d_{prop.to}M_*_ scaling, with a typical disk-to-star mass ratio of ~0.2%-0.6%. The measured rms dispersion around this regression curve is +/-0.7dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of ~40 on the inferred M_d_ (or L_mm_) at any given host mass.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/113/10
- Title:
- Sub-mJy radio sources complete sample
- Short Name:
- J/PASP/113/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Very Large Array has been used in C configuration to map an area ~=0.3deg^2^ at 1.4GHz with 5{sigma} sensitivities of 0.305, 0.325, 0.380, and 0.450mJy/beam over four equal subareas. Radio properties are presented for 62 detected sources. Deep optical imaging to Gunn r ~=25mag using the Hale 5m telescope covering ~=0.21deg^2^ is reported for a subset of 43 sources. This optical follow-up is much deeper than that of existing larger area radio surveys of similar radio sensitivity. Archival J-, H-, and K-band photometry from the Two-Micron All Sky Survey is also presented. Using a robust likelihood ratio technique, we optically identified 26 radio sources with probability >~80%, nine with uncertain/ambiguous detections, and eight with empty fields. Comparisons with a stellar synthesis model that includes radio emission and dust reddening suggest that the near-infrared-optical emission in a small, bright subsample is reddened by "optically thin" dust with absorption A_V_~=22.5mag, regardless of morphological type. This is consistent with other, more direct determinations of absorption. The radio-optical(-near-infrared) flux ratios of early-type galaxies require significant contamination in the radio by an active galactic nucleus, consistent with the current paradigm. Using our simple modeling approach, we also discuss a potential diagnostic for selecting ultraluminous infrared galaxies to z~=1.6 from microJansky radio surveys.
- ID:
- ivo://CDS.VizieR/J/MNRAS/430/1171
- Title:
- Sub-stellar birth rate from UKIDSS
- Short Name:
- J/MNRAS/430/1171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of mid-L to mid-T dwarfs with effective temperatures of 1100-1700K selected from the UKIDSS Large Area Survey (LAS) and confirmed with infrared spectra from X-shooter/Very Large Telescope. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our programme, covering 495 square degrees of sky, complete to J=18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of masses 0.10-0.03M_{sun}_ and ages 1-10Gyr. We find that the more extreme birth rates (e.g. a halo type form) can likely be excluded as the true form of the birth rate. In addition, we find that although there is substantial scatter we find a preference for a mass function, with a power-law index {alpha} in the range -1<{alpha}<0 that is consistent (within the errors) with the studies of late T dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/155
- Title:
- Sub-stellar companions in Taurus
- Short Name:
- J/ApJ/799/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive Taurus members at ~3M_{sun}_ and low-mass stars at ~0.2M_{sun}_. We detected 74 companion candidates, 34 of these reported for the first time. Twenty-five companions are likely physically bound, partly confirmed by follow-up observations. Four candidate companions are likely unrelated field stars. Assuming physical association with their host star, estimated companion masses are as low as ~2M_Jup_. The inferred multiplicity frequency within our sensitivity limits between ~10-1500AU is 26.3_-4.9_^+6.6^%. Applying a completeness correction, 62%+/-14% of all Taurus stars between 0.7 and 1.4M_{sun}_ appear to be multiple. Higher order multiples were found in 1.8_-1.5_^+4.2^% of the cases, in agreement with previous observations of the field. We estimate a sub-stellar companion frequency of ~3.5%-8.8% within our sensitivity limits from the discovery of two likely bound and three other tentative very low-mass companions. This frequency appears to be in agreement with what is expected from the tail of the stellar companion mass ratio distribution, suggesting that stellar and brown dwarf companions share the same dominant formation mechanism. Further, we find evidence for possible evolution of binary parameters between two identified sub-populations in Taurus with ages of ~2Myr and ~20Myr, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/610/1064
- Title:
- Substellar population of lambda Ori
- Short Name:
- J/ApJ/610/1064
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By collecting optical and infrared photometry and low-resolution spectroscopy, we have identified a large number of low-mass stars and brown dwarf candidates belonging to the young cluster (~5Myr) associated with the binary star {lambda} Orionis. The lowest mass object found is an M8.5 with an estimated mass of 0.02M_{Sun}_ (~0.01M_{Sun}_ for objects without spectroscopic confirmation). For those objects with spectroscopy, the measured strength of the H{alpha} emission line follows a distribution similar to other clusters with the same age range, with larger equivalent widths for cooler spectral types.
- ID:
- ivo://CDS.VizieR/J/A+A/402/151
- Title:
- S5 0716+714 UBVRI photometry
- Short Name:
- J/A+A/402/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 4854 UBVRI photometric data on the BL Lacertae object S5 0716+71 taken from 8 Observatories in the period 1994-2001 are presented; a table for each optical band is given, containing the observation time, the source magnitude, the error on the source magnitude, and a label indicating the Observatory where the observation was done.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A115
- Title:
- SUDARE-VOICE variability-selection of AGN
- Short Name:
- J/A+A/579/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the most peculiar characteristics of active galactic nuclei (AGNs) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied in future multi-epoch surveys, complementing photometric and spectroscopic methods. In this paper, we aim to construct and characterise an AGN sample using a multi-epoch dataset in the r band from the SUDARE-VOICE survey. Our work makes use of the VST monitoring programme of an area surrounding the Chandra Deep Field South to select variable sources. We use data spanning a six-month period over an area of 2 square degrees, to identify AGN based on their photometric variability. The selected sample includes 175 AGN candidates with magnitude r<23mag. We distinguish different classes of variable sources through their lightcurves, as well as X-ray, spectroscopic, SED, optical, and IR information overlapping with our survey. We find that 12% of the sample (21/175) is represented by supernovae (SN). Of the remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs based on the available diagnostics. We estimate an upper limit to the contamination of the variability selected AGN sample =~34%, but we point out that restricting the analysis to the sources with available multi-wavelength ancillary information, the purity of our sample is close to 80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our work thus confirms the efficiency of the variability selection method, in agreement with our previous work on the COSMOS field. In addition we show that the variability approach is roughly consistent with the infrared selection.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/145
- Title:
- Sulfur isotopes in SFR with 12m ARO and 30m IRAM
- Short Name:
- J/ApJ/899/145
- Date:
- 14 Mar 2022 07:08:41
- Publisher:
- CDS
- Description:
- We present observations of 12C32S, 12C34S, 13C32S, and 12C33S J=2-1 lines toward a large sample of massive star-forming regions by using the Arizona Radio Observatory 12m telescope and the IRAM 30m. Taking new measurements of the carbon 12C/13C ratio, the 32S/34S isotope ratio was determined from the integrated 13C32S/12C34S line intensity ratios for our sample. Our analysis shows a 32S/34S gradient from the inner Galaxy out to a galactocentric distance of 12kpc. An unweighted least-squares fit to our data yields 32S/34S=(1.56{+/-}0.17)DGC+(6.75{+/-}1.22) with a correlation coefficient of 0.77. Errors represent 1{sigma} standard deviations. Testing this result by (a) excluding the Galactic center region, (b) excluding all sources with C34S opacities >0.25, (c) combining our data and old data from previous study, and (d) using different sets of carbon isotope ratios leads to the conclusion that the observed 32S/34S gradient is not an artifact but persists irrespective of the choice of sample and carbon isotope data. A gradient with rising 32S/34S values as a function of galactocentric radius implies that the solar system ratio should be larger than that of the local interstellar medium. With the new carbon isotope ratios, we indeed obtain a local 32S/34S isotope ratio about 10% below the solar system one, as expected in the case of decreasing 32S/34S ratios with time and increased amounts of stellar processing. However, taking older carbon isotope ratios based on a lesser amount of data, such a decrease is not seen. No systematic variation of 34S/33S ratios along galactocentric distance was found. The average value is 5.9{+/-}1.5, the error denoting the standard deviation of an individual measurement.
6489. SUMaC I
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/4540
- Title:
- SUMaC I
- Short Name:
- J/MNRAS/466/4540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Swift Ultraviolet Survey of the Magellanic Clouds, the highest resolution ultraviolet (UV) survey of the Magellanic Clouds yet completed. In this paper, we focus on the Small Magellanic Cloud (SMC). When combined with multiwavelength optical and infrared observations, the three near-UV filters on the Swift Ultraviolet/Optical Telescope are conducive to measuring the shape of the dust extinction curve and the strength of the 2175{AA} dust bump. We divide the SMC into UV-detected star-forming regions and large 200-arcsec (58pc) pixels and then model the spectral energy distributions using a Markov-chain Monte Carlo method to constrain the ages, masses, and dust curve properties. We find that the majority of the SMC has a 2175{AA} dust bump, which is larger to the north-east and smaller to the south-west, and that the extinction curve is predominantly steeper than the Galactic curve. We also derive a star formation history and find evidence for peaks in the star formation rate at 6-10, 30-80, and 400Myr, the latter two of which are consistent with previous work.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/4
- Title:
- SuperBoRG: search HST parallel imaging data
- Short Name:
- J/ApJS/253/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope (HST) has been providing tremendous survey efficiency via its pure-parallel mode by observing another field in parallel with the primary instrument in operation for the primary observation. In this study, we present a new archival project, SuperBoRG, which aims at compiling data taken in extragalactic parallel programs of HST with the Wide Field Camera 3 in the past decade, including pure-parallel (BoRG, HIPPIES, and COS-GTO) and coordinated-parallel (CLASH and RELICS) programs. The total effective area reaches ~0.41deg^2^ from 4.1Ms, or 47days, of observing time, which is the largest collection of optical-to-near-infrared imaging data of HST for extragalactic science. We reduce all data in a consistent manner with an updated version of our data reduction pipeline, including a new sky background subtraction step. When available, imaging data from the Spitzer Space Telescope are also included in photometric analyses. The data set consists of 316 independent sight lines and is highly effective for identification of high-z luminous sources (M_UV_<~-20mag) at z~7-12, helping to minimize the effects of cosmic variance. As a demonstration, we present three new z>~7 source candidates, including one luminous galaxy candidate at z_phot_~10.4 with M_UV_~-21.9mag; the best-fit spectral energy distribution implies a large amount of stellar mass (logM_*_/M_{sun}_~10) and moderate dust attenuation (A_V_~1.4mag), though the possibility of it being a low-z interloper cannot be completely rejected (~23%) with the current data set. The data set presented in this study is also suited for intermediate- and low-z science cases.
