- ID:
- ivo://CDS.VizieR/J/ApJ/834/142
- Title:
- Gould's Belt Distances Survey (GOBELINS). II. OMC
- Short Name:
- J/ApJ/834/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the Gould's Belt Distances Survey of young star-forming regions toward the Orion Molecular Cloud Complex. We detected 36 young stellar objects (YSOs) with the Very Large Baseline Array, 27 of which have been observed in at least three epochs over the course of two years. At least half of these YSOs belong to multiple systems. We obtained parallax and proper motions toward these stars to study the structure and kinematics of the Complex. We measured a distance of 388+/-5pc toward the Orion Nebula Cluster, 428+/-10pc toward the southern portion L1641, 388+/-10pc toward NGC 2068, and roughly ~420pc toward NGC 2024. Finally, we observed a strong degree of plasma radio scattering toward {lambda} Ori.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/818/116
- Title:
- Gould's Belt VLA survey. V. Perseus region
- Short Name:
- J/ApJ/818/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiepoch, large-scale (~2000 arcmin^2^), fairly deep (~16 {mu}Jy), high-resolution (~1") radio observations of the Perseus star-forming complex obtained with the Karl G. Jansky Very Large Array at frequencies of 4.5 and 7.5 GHz. These observations were mainly focused on the clouds NGC 1333 and IC 348, although we also observed several fields in other parts of the Perseus complex. We detect a total of 206 sources, 42 of which are associated with young stellar objects (YSOs). The radio properties of about 60% of the YSOs are compatible with a nonthermal radio emission origin. Based on our sample, we find a fairly clear relation between the prevalence of nonthermal radio emission and evolutionary status of the YSOs. By comparing our results with previously reported X-ray observations, we show that YSOs in Perseus follow a Gudel-Benz relation with {kappa}=0.03, consistent with other regions of star formation. We argue that most of the sources detected in our observations but not associated with known YSOs are extragalactic, but provide a list of 20 unidentified radio sources whose radio properties are consistent with being YSO candidates. Finally, we also detect five sources with extended emission features that can clearly be associated with radio galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A25
- Title:
- GPS radio sources multifrequency study
- Short Name:
- J/A+A/544/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gigahertz peaked spectrum (GPS) radio sources are a class of extragalactic radio sources characterized by a spectral peak in the gigahertz domain. They are a mixed class of quasars and galaxies. A large proportion of the sources studied in the literature have only few data points in the radio domain, and the determination of variability and shape of the simultaneous spectra is inadequate. Sources currently included in the GPS source lists are very heterogeneous. We present the observational results from 12 observing campaigns (carried out between 2006 and 2010) at the RATAN-600 radio telescope to obtain the simultaneous radio spectra, which is valuable and necessary to derive genuine GPS sources from flat-spectrum radio sources caught in a flaring state when their spectra are temporarily inverted. The sample contains both quasar- and galaxy-type GPS (122 sources) identified in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJ/713/671
- Title:
- Gravitational waves from pulsars
- Short Name:
- J/ApJ/713/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search, ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present updated limits on gravitational radiation from the Crab pulsar, where the measured limit is now a factor of 7 below the spin-down limit. This limits the power radiated via gravitational waves to be less than ~2% of the available spin-down power. For the X-ray pulsar J0537-6910 we reach the spin-down limit under the assumption that any gravitational wave signal from it stays phase locked to the X-ray pulses over timing glitches, and for pulsars J1913+1011 and J1952+3252 we are only a factor of a few above the spin-down limit. Of the recycled millisecond pulsars, several of the measured upper limits are only about an order of magnitude above their spin-down limits. For these our best (lowest) upper limit on gravitational wave amplitude is 2.3x10^-26^ for J1603-7202 and our best (lowest) limit on the inferred pulsar ellipticity is 7.0x10^-8^ for J2124-3358.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/1587
- Title:
- GRS/BGPS sources in Galactic Plane
- Short Name:
- J/MNRAS/431/1587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The line of sight through the Galactic plane between longitudes l=37.83{deg} and 42.50{deg} allows for the separation of Galactic Ring Survey molecular clouds into those that fall within the spiral arms and those located in the interarm regions. By matching these clouds in both position and velocity with dense clumps detected in the mm continuum by the Bolocam Galactic Plane Survey, we are able to look for changes in the clump formation efficiency (CFE), the ratio of clump to cloud mass, with Galactic environment. We find no evidence of any difference in the CFE between the interarm and spiral-arm regions along this line of sight. This is further evidence that, outside the Galactic Centre region, the large-scale structures of the Galaxy play little part in changing the dense, potentially star-forming structures within molecular clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A57
- Title:
- G328.2551-0.5321 spectra
- Short Name:
- J/A+A/632/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Classical hot cores are rich in molecular emission, and they show a high abundance of complex organic molecules (COMs). The emergence of molecular complexity that is represented by COMs, in particular, is poorly constrained in the early evolution of hot cores. We put observational constraints on the physical location of COMs in a resolved high-mass protostellar envelope associated with the G328.2551-0.5321 clump. The protostar is single down to 400au scales and we resolved the envelope structure down to this scale. High angular resolution observations using the Atacama Large Millimeter Array allowed us to resolve the structure of the inner envelope and pin down the emission region of COMs. We use local thermodynamic equilibrium modelling of the available 7.5GHz bandwidth around 345GHz to identify the COMs towards two accretion shocks and a selected position representing the bulk emission of the inner envelope. We quantitatively discuss the derived molecular column densities and abundances towards these positions, and use our line identification to qualitatively compare this to the emission of COMs seen towards the central position, corresponding to the protostar and its accretion disk. We detect emission from 10 COMs, and identify a line of deuterated water (HDO). In addition to methanol (CH_3_OH), methyl formate (CH_3_OCHO) and formamide (HC(O)NH_2_) have the most extended emission. Together with HDO, these molecules are found to be associated with both the accretion shocks and the inner envelope, which has a moderate temperature of Tkin~110K. We find a significant difference in the distribution of COMs. O-bearing COMs, such as ethanol, acetone, and ethylene glycol are almost exclusively found and show a higher abundance towards the accretion shocks with Tkin~180K. Whereas N-bearing COMs with a CN group, such as vinyl and ethyl cyanide peak on the central position, thus the protostar and the accretion disk. The molecular composition is similar towards the two shock positions, while it is significantly different towards the inner envelope, suggesting an increase in abundance of O-bearing COMs towards the accretion shocks. We present the first observational evidence for a large column density of COMs seen towards accretion shocks at the centrifugal barrier at the inner envelope. The overall molecular emission shows increased molecular abundances of COMs towards the accretion shocks compared to the inner envelope. The bulk of the gas from the inner envelope is still at a moderate temperature of Tkin~110K, and we find that the radiatively heated inner region is very compact (<1000au). Since the molecular composition is dominated by that of the accretion shocks and the radiatively heated hot inner region is very compact, we propose this source to be a precursor to a classical, radiatively heated hot core. By imaging the physical location of HDO, we find that it is consistent with an origin within the moderately heated inner envelope, suggesting that it originates from sublimation of ice from the grain surface and its destruction in the vicinity of the heating source has not been efficient yet.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/2500
- Title:
- GX 339-4 radio/X-ray flux correlation
- Short Name:
- J/MNRAS/428/2500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The existing radio and X-ray flux correlation for Galactic black holes in the hard and quiescent states relies on a sample which is mostly dominated by two sources (GX 339-4 and V404 Cyg) observed in a single outburst. In this paper, we report on a series of radio and X-ray observations of the recurrent black hole GX 339-4 with the Australia Telescope Compact Array, the Rossi X-ray Timing Explorer and the Swift satellites. With our new long-term campaign, we now have a total of 88 quasi-simultaneous radio and X-ray observations of GX 339-4 during its hard state, covering a total of seven outbursts over a 15-yr period. Our new measurements represent the largest sample for a stellar mass black hole, without any bias from distance uncertainties, over the largest flux variations and down to a level that could be close to quiescence, making GX 339-4 the reference source for comparison with other accreting sources (black holes, neutrons stars, white dwarfs and active galactic nuclei).
- ID:
- ivo://jvo/isas/darts/halca/halca_vsop_correlated_data
- Title:
- HALCA VSOP (the VLBI Space Observatory Programme) Correlated Data
- Short Name:
- HALCA
- Date:
- 19 Oct 2021 07:12:04
- Publisher:
- JVO
- Description:
- The VSOP (VLBI Space Observatory Programme) mission was led by the Institute of Space and Astronautical Science, in collaboration with the National Astronomical Observatory of Japan with international collaboration with NSAS, CSA, JIVE and the world radio telescopes in 14 countries. This mission provided a dedicated space radio telescope "HALCA" launched in February 1997, and carried out high-resolution observations at 1.6, 5.0, and 22 GHz with ground radio observatories to perform Very Long Baseline Interferometry (VLBI) on baselines of up to 2.6 Earth diameters. The observations are continued till 2003, and HALCA finished its operation in 2005.
- ID:
- ivo://CDS.VizieR/VIII/7A
- Title:
- Hat Creek High-Latitude H I Survey
- Short Name:
- VIII/7A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This survey consists of H I 21-cm spectra covering the entire northern sky with absolute Galactic latitude |b|>10 degrees and declination dec>-30degrees. The observations were made with the Hat Creek 85-foot telescope between 1968 and 1970. The individual spectra were obtained with a bank of 100 filters covering the velocity range from -92km/s to +75km/s. The velocity resolution was 2 km/sec (except at the ends of the spectra) and the beamwidth was 36arcmin. The spacing between points observed on the sky is (0.3deg/cosb) in Galactic longitude and (0.6deg) in Galactic latitude. A FITS version of the survey was derived at the Astrophysics Data Facility (NASA/GSFC) from the original catalog of spectra. The approximately 130,000 good spectra in the catalog (i.e., those with status code 1 and which have flat baselines) were interpolated to a uniform channel width in frequency, shifted as appropriate to take into account the proper central velocities, then interpolated onto a regular grid in Galactic coordinates. For the latter interpolation, the cos(b) corrections for longitude offsets were taken into account; no interpolation was done across gaps in coverage greater than 2 deg. Latitude-velocity slices were written in FITS format for each 30 arcmin of longitude. Separate files were written for the negative latitude (b < -10 deg ) and positive latitude (b > 10 deg) ranges. Slices containing no spectra, primarily negative latitude spectra in the fourth Galactic quadrant, were not written. A longitude-latitude map, integrated over all velocities, was also written in FITS format to illustrate the coverage of the individual latitude-velocity slices.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/1910
- Title:
- H-ATLAS NGP LOFAR radio catalogue
- Short Name:
- J/MNRAS/462/1910
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Low-Frequency Array (LOFAR) High-Band Array observations of the Herschel-ATLAS North Galactic Pole survey area. The survey we have carried out, consisting of four pointings covering around 142deg^2^ of sky in the frequency range 126-173MHz, does not provide uniform noise coverage but otherwise is representative of the quality of data to be expected in the planned LOFAR wide-area surveys, and has been reduced using recently developed 'facet calibration' methods at a resolution approaching the full resolution of the data sets (~10x6 arcsec) and an rms off-source noise that ranges from 100{mu}Jy beam^-1^ in the centre of the best fields to around 2mJy/beam at the furthest extent of our imaging. We describe the imaging, cataloguing and source identification processes, and present some initial science results based on a 5{sigma} source catalogue. These include (i) an initial look at the radio/far-infrared correlation at 150 MHz, showing that many Herschel sources are not yet detected by LOFAR; (ii) number counts at 150MHz, including, for the first time, observational constraints on the numbers of star-forming galaxies; (iii) the 150-MHz luminosity functions for active and star-forming galaxies, which agree well with determinations at higher frequencies at low redshift, and show strong redshift evolution of the star-forming population; and (iv) some discussion of the implications of our observations for studies of radio galaxy life cycles.
