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451. Radial velocities of SMC massive stars
ID:
ivo://CDS.VizieR/J/MNRAS/386/826
Title:
Radial velocities of SMC massive stars
Short Name:
J/MNRAS/386/826
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present radial velocities for 2045 stars in the Small Magellanic Cloud (SMC), obtained from the 2dF survey by Evans et al. (2004, Cat. J/MNRAS/353/601). The great majority of these stars are of OBA type, tracing the dynamics of the young stellar population. Dividing the sample into ad hoc `bar' and `wing' samples (north and south, respectively, of the line: delta=-77^{deg}50' + [4{alpha}]', where alpha is in minutes of time) we find that the velocities in the SMC bar show a gradient of 26.3+/-1.6km/s/deg at a position angle of 126+/-4deg. The derived gradient in the bar is robust to the adopted line of demarcation between the two samples. The largest redshifts are found in the SMC wing, in which the velocity distribution appears distinct from that in the bar, most likely a consequence of the interaction between the Magellanic Clouds that is predicted to have occurred 0.2Gyr ago. The mean velocity for all stars in the sample is +172.0+/-0.2km/s (redshifted by ~20km/s when compared to published results for older populations), with a velocity dispersion of 30km/s.
452. Radial velocity curves of LMC ellipsoidal variables
ID:
ivo://CDS.VizieR/J/AJ/148/118
Title:
Radial velocity curves of LMC ellipsoidal variables
Short Name:
J/AJ/148/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ellipsoidal red giant binaries are close binary systems where an unseen, relatively close companion distorts the red giant, leading to light variations as the red giant moves around its orbit. These binaries are likely to be the immediate evolutionary precursors of close binary planetary nebula and post-asymptotic giant branch and post-red giant branch stars. Due to the MACHO and OGLE photometric monitoring projects, the light variability nature of these ellipsoidal variables has been well studied. However, due to the lack of radial velocity curves, the nature of their masses, separations, and other orbital details has so far remained largely unknown. In order to improve this situation, we have carried out spectral monitoring observations of a large sample of 80 ellipsoidal variables in the Large Magellanic Cloud and we have derived radial velocity curves. At least 12 radial velocity points with good quality were obtained for most of the ellipsoidal variables. The radial velocity data are provided with this paper. Combining the photometric and radial velocity data, we present some statistical results related to the binary properties of these ellipsoidal variables.
453. Radial velocity measurements of 20 EBs in LMC
ID:
ivo://CDS.VizieR/J/ApJ/860/1
Title:
Radial velocity measurements of 20 EBs in LMC
Short Name:
J/ApJ/860/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a determination of the precise fundamental physical parameters of 20 detached, double-lined, eclipsing binary stars in the Large Magellanic Cloud (LMC) containing G- or early K-type giant stars. Eleven are new systems; the remaining nine are systems already analyzed by our team for which we present updated parameters. The catalog results from our long-term survey of eclipsing binaries in the Magellanic Clouds suitable for high-precision determination of distances (the Araucaria Project). The V-band brightnesses of the systems range from 15.4 to 17.7mag, and their orbital periods range from 49 to 773days. Six systems have favorable geometry showing total eclipses. The absolute dimensions of all eclipsing binary components are calculated with a precision of better than 3%, and all systems are suitable for a precise distance determination. The measured stellar masses are in the range 1.4 to 4.6M_{sun}_, and comparison with the MESA isochrones gives ages between 0.1 and 2.1Gyr. The systems show an age-metallicity relation with no evolution of metallicity for systems older than 0.6Gyr, followed by a rise to a metallicity maximum at age 0.5Gyr and then a slow metallicity decrease until 0.1Gyr. Two systems have components with very different masses: OGLE LMC-ECL-05430 and OGLE LMC-ECL-18365. Neither system can be fitted by a single stellar evolution isochrone, explained by a past mass transfer scenario in the case of ECL-18365 and a gravitational capture or hierarchical binary merger scenario in the case of ECL-05430. The longest-period system, OGLE LMC SC9_230659, shows a surprising apsidal motion that shifts the apparent position of the eclipses. This is a clear sign of a physical companion to the system; however, neither investigation of the spectra nor light-curve analysis indicates a third-light contribution larger than 2%-3%. In one spectrum of OGLE LMC-ECL-12669, we noted a peculiar dimming of one of the components by 65% well outside of the eclipses. We interpret this observation as arising from an extremely rare occultation event, as a foreground Galactic object covers only one component of an extragalactic eclipsing binary.
454. Radio and UV spectra of HVC toward the MC
ID:
ivo://CDS.VizieR/J/ApJ/702/940
Title:
Radio and UV spectra of HVC toward the MC
Short Name:
J/ApJ/702/940
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the spectra of 139 early-type Large Magellanic Cloud (LMC) stars observed with Far Ultraviolet Spectroscopic Explorer and with deep radio Parkes HI 21cm observations along with those stars, we search for and analyze the absorption and emission from high-velocity gas at +90<={nu}_LSR_<=+175km/s. The HI column density of the high-velocity clouds (HVCs) along these sightlines ranges from <1018.4 to 1019.2cm^-2^. The incidence of the HVC metal absorption is 70%, significantly higher than the HI emission occurrence of 32%. We find that the mean metallicity of the HVC is [OI/HI]=-0.51+/-^0.12^_0.16_. This is the first example of a large (>10^6^M_{sun}_) HVC complex that is linked to stellar feedback occurring in a dwarf spiral galaxy.
455. Radio continuum sources behind LMC
ID:
ivo://CDS.VizieR/J/MNRAS/507/2885
Title:
Radio continuum sources behind LMC
Short Name:
J/MNRAS/507/2885
Date:
07 Feb 2022 08:00:21
Publisher:
CDS
Description:
We present a comprehensive multifrequency catalogue of radio sources behind the Large Magellanic Cloud (LMC) between 0.2 and 20GHz, gathered from a combination of new and legacy radio continuum surveys. This catalogue covers an area of ~144deg^2^ at angular resolutions from 45 arcsec to ~3 arcmin. We find 6434 discrete radio sources in total, of which 3789 are detected at two or more radio frequencies. We estimate the median spectral index ({alpha}; where S_v_~{nu}^{alpha}^) of {alpha}=-0.89 and mean of -0.88+/-0.48 for 3636 sources detected exclusively at two frequencies (0.843 and 1.384GHz) with similar resolution [full width at half-maximum (FWHM) ~40-45 arcsec]. The large frequency range of the surveys makes it an effective tool to investigate Gigahertz Peak Spectrum (GPS), Compact Steep Spectrum (CSS), and Infrared Faint Radio Source (IFRS) populations within our sample. We find 10 GPS candidates with peak frequencies near 5GHz, from which we estimate their linear size. 1866 sources from our catalogue are CSS candidates with {alpha}<-0.8. We found six candidates for High Frequency Peaker (HFP) sources, whose radio fluxes peak above 5GHz and no sources with unconstrained peaks and {alpha}>0.5. We found optical counterparts for 343 of the radio continuum sources, of which 128 have a redshift measurement. Finally, we investigate the population of 123 IFRSs found in this study.
456. Radio continuum study of the MC
ID:
ivo://CDS.VizieR/J/A+AS/111/311
Title:
Radio continuum study of the MC
Short Name:
J/A+AS/111/311
Date:
21 Oct 2021
Publisher:
CDS
Description:
From observations with the Parkes radio telescope, we present catalogues of radio sources in the Large Magellanic Cloud at four frequencies: 1.40, 2.45, 4.75 and 8.55GHz, and an additional catalogue from a source analysis of the Parkes-MIT-NRAO survey at 4.85GHz. A total of 469 sources have been detected at least one of these frequencies, 132 of which are reported here for the first time as radio sources.
457. Radio continuum study of the MC
ID:
ivo://CDS.VizieR/J/A+AS/127/119
Title:
Radio continuum study of the MC
Short Name:
J/A+AS/127/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
By comparing Parkes telescope radio surveys with the X-ray ROSAT All-Sky Survey (RASS) we have found 71 discrete sources of both radio and X-ray emission in the Large Magellanic Cloud (LMC). These 71 sources are mainly supernova remnants (SNRs) and SNR candidates (36), and background sources (27). For six of the sources we have no proposed identification and the other two are HII regions. A source-intensity comparison of the radio and X-ray sources shows very little correlation, but we note that the strongest SNRs at both radio and X-ray frequencies are young SNRs from Population I. Six new LMC SNR candidates are proposed. From the radio flux density of the SNRs we have estimated the SNR birth rate to be one every 100 (+/-20) yr and the star-formation rate (SFR) to be 0.7 (+/-0.2)M_{sun}_/yr. A similar comparison was undertaken for the Small Magellanic Cloud (SMC), but instead of the RASS we used a roster of pointed observations made with the ROSAT Position Sensitive Proportional Counter (PSPC). This comparison resulted in 27 sources in common between the Parkes radio and ROSAT PSPC surveys. Two new SMC sources are proposed for SNR candidates. The SMC SNR birth rate was estimated to be one every 350 (+/-70)yr and the SFR was estimated to be 0.15 (+/-0.05)M_{sun}_/yr.
458. Radio continuum study of the MC
ID:
ivo://CDS.VizieR/J/A+AS/120/77
Title:
Radio continuum study of the MC
Short Name:
J/A+AS/120/77
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new catalogue of radio sources in the Large Magellanic Cloud (LMC) based on observations at 2.30GHz with the Parkes radio telescope. A total of 119 sources have been detected. We compare positions and flux densities of these sources with previously published radio results and find no significant positional displacement or flux discrepancies.
459. Radio continuum study of the MC
ID:
ivo://CDS.VizieR/J/A+AS/130/421
Title:
Radio continuum study of the MC
Short Name:
J/A+AS/130/421
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of discrete radio sources in the Magellanic Clouds (MCs) using the latest large-scale radio surveys made with the Parkes radio telescope between 1.4 and 8.55GHz. These surveys achieved higher sensitivity than previous surveys done with the Parkes telescope and so the number of discrete radio sources detected towards the MCs has increased by factor of five. Also, we have obtained improved positions, flux densities and radio spectral indices for all of these sources. A total of 483 sources towards the Large Magellanic Cloud (LMC) and 224 towards the Small Magellanic Cloud (SMC) have been detected at at least one radio frequency. Most of the MC's sources have been classified in one of three groups: SNRs, HII regions or background sources according to classification criteria established here. In total, 209 discrete radio sources in the LMC and the 37 sources in the SMC are classified here to be either HII regions or SNRs. We investigate their luminosity functions as well as the statistics of background sources behind the MCs. Also, we examine the distribution of SNRs and HII regions in the MCs.
460. Radio Survey of X-ray sources
ID:
ivo://CDS.VizieR/J/MNRAS/298/692
Title:
Radio Survey of X-ray sources
Short Name:
J/MNRAS/298/692
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a radio survey of X-ray sources in the Large and Small Magellanic clouds with the Australia Telescope Compact Array at 6.3 and 3.5 cm. Specifically, we have observed the fields of five LMC and two SMC supersoft X-ray sources, the X-ray binaries LMC X-1, X-2, X-3 & X-4, the X-ray transient Nova SMC 1992, and the soft gamma-ray repeater SGR 0525-66. None of the targets are detected as point sources at their catalogued positions. In particular, the proposed supersoft jet source RXJ 0513-69 is not detected, placing constraints on its radio luminosity compared to Galactic jet sources. Limits on emission from the black hole candidate systems LMC X-1 and X-3 are consistent with the radio behaviour of persistent Galactic black hole X-ray binaries, and a previous possible radio detection of LMC X-1 is found to almost certainly be due to nearby field sources. The SNR N49 in the field of SGR 0525-66 is mapped at higher resolution than previously, but there is still no evidence for any enhanced emission or disruption of the SNR at the location of the X-ray source. No radio point sources were detected at any wavelength at the catalogued locations of the target sources. In most cases a noise level of 50 microJy or so was achieved, making the 3-sigma upper limits very stringent indeed. The noise levels for LMC X-1 and SGR 0525-66 are considerably worse, due to their locations in radio-bright regions.