- ID:
- ivo://CDS.VizieR/J/ApJS/120/247
- Title:
- Supernova remnants in M33
- Short Name:
- J/ApJS/120/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using radio data to identify and optical data to confirm, we have established the largest and most complete sample of extragalactic radio-bright supernova remnants (SNRs) in the nearby spiral galaxy M33. We have identified 53 radio SNRs, doubling the size of the earlier survey by Duric et al. (1993A&AS...99..217D).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/467/785
- Title:
- SuperWASP/ROSAT periodic variable stars
- Short Name:
- J/A+A/467/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical lightcurves of 428 periodic variable stars coincident with ROSAT X-ray sources, detected using the first run of the SuperWASP photometric survey. Only 68 of these were previously recognised as periodic variables. A further 30 of these objects are previously known pre-main sequence stars, for which we detect a modulation period for the first time. Amongst the newly identified periodic variables, many appear to be close eclipsing binaries, their X-ray emission is presumably the result of RS CVn type behaviour. Others are probably BY Dra stars, pre-main sequence stars and other rapid rotators displaying enhanced coronal activity. A number of previously catalogued pulsating variables (RR Lyr stars and Cepheids) coincident with X-ray sources are also seen, but we show that these are likely to be misclassifications. We identify four objects which are probable low mass eclipsing binary stars, based on their very red colour and light curve morphology.
- ID:
- ivo://CDS.VizieR/J/A+AS/77/31
- Title:
- Survey at 408 MHz and 1420 MHz towards A 1314
- Short Name:
- J/A+AS/77/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cluster of galaxies Abell 1314 has been observed with the Penticton synthesis telescope simultaneously at 408 MHz (73.5 cm wavelength) with a sensitivity (7 rms) near 70 mJy and at 1420 MHz (21.1 cm wavelength) with a sensitivity (5 rms) near 4.3 mJy. In addition to the 3 cluster sources detected, a further 64 background radio sources have been detected at 1420 MHz (the 20P radio survey), and 169 background sources at 408 MHz (the 21P radio survey). The surveys extend to a radius of 3.7 degrees at 408 MHz, and to 1.0 degree at 1420 MHz, from the map center at RA=11h31.5m, Dec=+49d20'. The differential source count for the background radio sources, derived at 408 MHz in the flux density range 90 mJy to 3.0 Jy, shows consistency with the Cambridge 5C5 survey at 408 MHz in a direction away from clusters of galaxies. Also, the differential count derived at 1420 MHz in the flux density range 10 mJy to 330 mJy is consistent with the Westerbork LBDS survey at a nearby frequency away from clusters of galaxies. We find no candidate for very steep spectrum "relic" sources in this cluster of galaxies, nor for very flat spectrum "blue" background radio galaxies behind the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJS/155/421
- Title:
- Survey of Galactic Center region at 20cm
- Short Name:
- J/ApJS/155/421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers presenting a sensitive 20cm VLA continuum survey of the Galactic center region using new and archival data based on multiconfiguration observations taken with relatively uniform uv coverage. The high dynamic range images cover the regions within -2{deg}<l<5{deg} and -40'<b<40' with a spatial resolution of ~30" and 10". The wide field imaging technique is used to construct a low-resolution mosaic of 40 overlapping pointings. The mosaic image includes the Effelsberg observations filling the low spatial frequency uv data. We also present high-resolution images of 23 overlapping fields using DnC and CnB array configurations. These high-resolution images are sensitive to both compact and extended continuum features with a wide range of angular scales with rms noise of 0.2mJy/beam in the outer parts of the Galactic center region. The survey has resulted in a catalog of 345 discrete sources as well as 140 images revealing structural details of HII regions, supernova remnants, pulsar wind nebulae, and more than 80 linear filaments distributed toward the complex region of the Galactic center.
- ID:
- ivo://CDS.VizieR/J/ApJ/526/788
- Title:
- Survey of infall motions toward starless cores
- Short Name:
- J/ApJ/526/788
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a survey of 220 starless cores selected primarily by their optical obscuration and observed in CS (2-1), N_2_H^+^ (1-0), and C^18^O (1-0) using the Northeast Radio Observatory Corporation (NEROC) Haystack 37 m telescope. We have detected 163 out of 196 sources observed in CS, 72 out of 142 in N_2_H^+^, and 30 out of 30 in C18O. In total, 69 sources were detected in both CS and N_2_H^+^. The isolated component of the N_2_H^+^ (1-0) spectrum (F_1_F = 0,1-1,2) usually shows a weak symmetric profile that is optically thin. In contrast, a significant fraction of the CS spectra show non-Gaussian shapes, which we interpret as arising from a combination of self-absorption due to lower excitation gas in the core front and kinematics in the core. The distribution of the normalized velocity difference ({delta}V_CS_) between the CS and N_2_H^+^ peaks appears significantly skewed to the blue (V_CS_ < 0), as was found in a similar study of dense cores with embedded young stellar objects (YSOs). The incidence of sources with blue asymmetry tends to increase as the total optical depth or the integrated intensity of the N_2_H^+^ line increases.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/44
- Title:
- Survey of SiO maser emission in oxygen-rich stars
- Short Name:
- J/ApJS/253/44
- Date:
- 01 Mar 2022 00:16:35
- Publisher:
- CDS
- Description:
- Circumstellar environments of oxygen-rich stars are among the strongest SiO maser emitters. Physical processes such as collisions, infrared pumping, and overlaps favor the inversion of level population and produce maser emission at different vibrational states. Despite numerous observational and theoretical efforts, we still do not have a unified picture including all of the physical processes involved in SiO maser emission. The aim of this work is to provide homogeneous data in a large sample of oxygen-rich stars. We present a survey of 67 oxygen-rich stars from 7 to 1mm, in their rotational transitions from J=1-0 to J=5-4, for vibrational numbers v from 0 to 6 in the three main SiO isotopologs. We have used one of the 34 m NASA antennas at Robledo and the IRAM 30m radio telescope. The first tentative detection of a v=6 line is reported, as well as the detection of new maser lines. The highest vibrational levels seem confined to small volumes, presumably close to the stars. The J=1-0, v=2 line flux is greater than the corresponding v=1 in almost half of the sample, which may confirm a predicted dependence on the pulsation cycle. This database is potentially useful in models which should consider most of the physical agents, time dependency, and mass-loss rates. As a by-product, we report detections of 27 thermal rotational lines from other molecules, including isotopologs of SiS, H_2_S, SO, SO_2_, and NaCl.
- ID:
- ivo://CDS.VizieR/J/A+AS/35/23
- Title:
- Survey of the Galactic Plane at 4.875 GHz
- Short Name:
- J/A+AS/35/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey of the galactic plane was made with the Effelsberg 100-m telescope at a frequency of 4.875 GHz with a beamwidth of 2.6 arcmin. Table 1 is a list of 1186 radio sources in the surveyed area l = 357.5 to 60 deg, b = -1 to +1 deg. The primary calibration source was NGC 7027, which was assumed to have a flux density of 5.9 Jy (1 Jy = 10^-26^W.m-2.Hz-1). The uncertainty in day-to-day thermal calibration was +/- 5 to 10%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/2747
- Title:
- S4 1030+61 VLBA observations, 2009-2014
- Short Name:
- J/MNRAS/462/2747
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the parsec-scale multifrequency properties of the quasar S4 1030+61 during a prolonged radio and {gamma}-ray activity. Observations were performed within Fermi {gamma}-ray telescope, Owens Valley Radio Observatory 40-m telescope and MOJAVE Very Long Baseline Array (VLBA) monitoring programmes, covering five years from 2009. The data are supplemented by four-epoch VLBA observations at 5, 8, 15, 24 and 43GHz, which were triggered by the bright {gamma}-ray flare, registered in the quasar in 2010. The S4 1030+61 jet exhibits an apparent superluminal velocity of (6.4+/-0.4)c and does not show ejections of new components in the observed period, while decomposition of the radio light curve reveals nine prominent flares. The measured variability parameters of the source show values typical for Fermi-detected quasars. Combined analysis of radio and {gamma}-ray emission implies a spatial separation between emitting regions at these bands of about 12pc and locates the {gamma}-ray emission within a parsec from the central engine. We detected changes in the value and direction of the linear polarization and the Faraday rotation measure. The value of the intrinsic brightness temperature of the core is above the equipartition state, while its value as a function of distance from the core is well approximated by the power law. Altogether these results show that the radio flaring activity of the quasar is accompanied by injection of relativistic particles and energy losses at the jet base, while S4 1030+61 has a stable, straight jet well described by standard conical jet theories.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A12
- Title:
- S5 0716+714 VLBI K- and Q-band variability
- Short Name:
- J/A+A/601/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study aims to search for the existence of intraday variability (IDV) of BL Lac object S5 0716+714 at high radio frequencies for which the interstellar scintillation effect is not significant. Using the 21-m radio telescope of the Korean VLBI Network (KVN), we present results of multi-epoch simultaneous dual-frequency radio observations. Single-dish observations of S5 0716+714 were simultaneously conducted at 21.7GHz (K-band) and 42.4GHz (Q-band), with a high cadence of 30-60min intervals. We observed four epochs between December 2009 and June 2010. Over the whole set of observation epochs, S5 0716+714 showed significant inter-month variations in flux density at both the K- and Q-bands, with modulation indices of approximately 19% for the K-band and approximately 36% for the Q-band. In all epochs, no clear intraday variability was detected at either frequency. The source shows monotonic flux density increase in epochs 1 and 3 and monotonic flux density decrease in epochs 2 and 4. In the flux density increasing phases, the flux densities at the Q-band increase more rapidly. In the decreasing phase, no significant flux density difference is seen at the two frequencies. The situation could be different close to flux density peaks that we did not witness in our observations. We find an inverted spectrum with mean spectral indices, {bar}{alpha}(S_{nu}_{prop.to}{nu}^-{alpha}^), of -0.57+/-0.13 in epoch 1 and -0.15+/-0.11 in epoch 3. On the other hand, we find relatively steep indices of +0.24+/-0.14 and +0.17+/-0.18 in epochs 2 and 4, respectively. We conclude that the frequency dependence of the variability and the change of the spectral index are caused by source-intrinsic effects rather than by any extrinsic scintillation effect.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/3265
- Title:
- Swift J1745-26 polarized jet
- Short Name:
- J/MNRAS/437/3265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Swift J1745-26 is an X-ray binary towards the Galactic Centre that was detected when it went into outburst in 2012 September. This source is thought to be one of a growing number of sources that display `failed outbursts', in which the self-absorbed radio jets of the transient source are never fully quenched and the thermal emission from the geometrically thin inner accretion disc never fully dominates the X-ray flux. We present multifrequency data from the Very Large Array, Australia Telescope Compact Array and Karoo Array Telescope (KAT-7) radio arrays, spanning the entire period of the outburst. Our rich data set exposes radio emission that displays a high level of large-scale variability compared to the X-ray emission and deviations from the standard radio-X-ray correlation that are indicative of an unstable jet and confirm the outburst's transition from the canonical hard state to an intermediate state. We also observe steepening of the spectral index and an increase of the linear polarization to a large fraction (~50%) of the total flux, as well as a rotation of the electric vector position angle. These are consistent with a transformation from a self-absorbed compact jet to optically thin ejecta - the first time such a discrete ejection has been observed in a failed outburst - and may imply a complex magnetic field geometry.
