- ID:
- ivo://CDS.VizieR/J/A+A/567/L5
- Title:
- W3(OH) high angular resolution 7mm images
- Short Name:
- J/A+A/567/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent high angular resolution radio observations of the ultracompact Hii region W3(OH) confirm the presence of an extremely compact (0.05"), time-variable source near its center. We use new, sensitive high angular resolution observations of radio continuum and recombination lines to study the compact source in W3(OH) and the ultracompact HII region itself. We reduced and analyzed extensive Jansky Very Large Array observations of W3(OH) in the continuum at 41.0GHz and in the H54{alpha} and He54{alpha} lines.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/331/949
- Title:
- Wolf-Rayet and O-star runaways kinematics
- Short Name:
- J/A+A/331/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Reliable systemic radial velocities are almost impossible to secure for Wolf-Rayet stars, difficult for O stars. Therefore, to study the motions - both systematic in the Galaxy and peculiar - of these two related types of hot, luminous star, we have examined the Hipparcos proper motions of some 70 stars of each type. We find that (a) both groups follow Galactic rotation in the same way, (b) both have a similar fraction of ``runaways'', (c) mean kinetic ages based on displacement and motion away from the Galactic plane tend to slightly favour the cluster ejection over the the binary supernova hypothesis for their formation, and (d) those with significant peculiar supersonic motion relative to the ambient ISM, tend to form bow shocks in the direction of the motion.
- ID:
- ivo://CDS.VizieR/J/AJ/146/162
- Title:
- Wolf-Rayet and RSG stars in M101. I. HST photometry
- Short Name:
- J/AJ/146/162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Assembling a catalog of at least 10000 Wolf-Rayet (W-R) stars is an essential step in proving (or disproving) that these stars are the progenitors of Type Ib and Type Ic supernovae. To this end, we have used the Hubble Space Telescope (HST) to carry out a deep, HeII optical narrowband imaging survey of the ScI spiral galaxy M101. Almost the entire galaxy was imaged with the unprecedented depth and resolution that only the HST affords. Differenced with archival broadband images, the narrowband images allow us to detect much of the W-R star population of M101. We describe the extent of the survey and our images, as well as our data reduction procedures. A detailed broadband-narrowband imaging study of a field east of the center of M101, containing the giant star-forming region NGC5462, demonstrates our completeness limits, how we find W-R candidates, their properties and spatial distribution, and how we rule out most contaminants. We use the broadband images to locate luminous red supergiant (RSG) candidates. The spatial distributions of the W-R and RSG stars near NGC 5462 are strikingly different. W-R stars dominate the complex core, while RSGs dominate the complex halo. Future papers in this series will describe and catalog more than a thousand W-R and RSG candidates that are detectable in our images, as well as spectra of many of those candidates.
21604. Wolf-Rayet content of M31
- ID:
- ivo://CDS.VizieR/J/ApJ/759/11
- Title:
- Wolf-Rayet content of M31
- Short Name:
- J/ApJ/759/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Wolf-Rayet (WR) stars are evolved massive stars, and the relative number of WC-type and WN-type WRs should vary with the metallicity of the host galaxy, providing a sensitive test of stellar evolutionary theory. However, past studies of the WR content of M31 have been biased toward detecting WC stars, as their emission-line signatures are much stronger than those of WNs. Here, we present the results of a survey covering all of M31's optical disk (2.2deg^2^), with sufficient sensitivity to detect the weaker-lined WN types. We identify 107 newly found WR stars, mostly of WN type. This brings the total number of spectroscopically confirmed WRs in M31 to 154, a number we argue is complete to ~95%, except in regions of unusually high reddening. This number is consistent with what we expect from the integrated H{alpha} luminosity compared to that of M33. The majority of these WRs formed in OB associations around the Population I ring, although 5% are truly isolated. Both the relative number of WC- to WN-type stars as well as the WC subtype distribution suggest that most WRs exist in environments with higher-than-solar metallicities, which is consistent with studies of M31's metallicity. Although the WC to WN ratio we find for M31 is much lower than that found by previous studies, it is still higher than what the Geneva evolutionary models predict. This may suggest that Roche-lobe overflow produces the excess of WC stars observed at high metallicity, or that the assumed rotational velocities in the models are too high.
- ID:
- ivo://CDS.VizieR/J/ApJ/655/851
- Title:
- Wolf-Rayet galaxies in the SDSS
- Short Name:
- J/ApJ/655/851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a large sample of 174 Wolf-Rayet (W-R) galaxies drawn from the Sloan Digital Sky Survey to study whether and how the slope of the stellar initial mass function depends on metallicity. We calculate for each object its oxygen abundance, according to which we divide our sample into four metallicity subsamples. For each subsample, we then measure three quantities: the equivalent width of the H{beta} emission line, the equivalent width of the W-R bump around 4650{AA}, and the W-R bump-to-Hbeta intensity ratio, and compare to the predictions of the same quantities by evolutionary synthesis models of Schaerer & Vacca (1998ApJ...497..618S).
21606. Wolf-Rayet population in M83
- ID:
- ivo://CDS.VizieR/J/A+A/439/265
- Title:
- Wolf-Rayet population in M83
- Short Name:
- J/A+A/439/265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of non-nuclear regions containing Wolf-Rayet stars in the metal-rich spiral galaxy M 83 (NGC 5236). From a total of 283 candidate regions identified using He II {lambda}4686 imaging with VLT-FORS2, Multi Object Spectroscopy of 198 regions was carried out, confirming 132 WR sources. From this sub-sample, an exceptional content of ~1035+/-300 WR stars is inferred, with N(WC)/N(WN) ~ 1.2, continuing the trend to larger values at higher metallicity amongst Local Group galaxies, and greatly exceeding current evolutionary predictions at high metallicity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/3091
- Title:
- Wolf-Rayet population in NGC 5068
- Short Name:
- J/MNRAS/420/3091
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a narrow-band Very Large Telescope/Focal Reduced Low-dispersion Spectrograph #1 imaging survey of the SAB(rs)cd spiral galaxy NGC 5068, located at a distance of 5.45Mpc, from which 160 candidate Wolf-Rayet sources have been identified, of which 59 cases possess statistically significant {lambda}4686 excesses. Follow-up Gemini Multi-Object Spectrograph spectroscopy of 64 candidates, representing 40 per cent of the complete photometric catalogue, confirms Wolf-Rayet signatures in 30 instances, corresponding to a 47 per cent success rate. 21 out of 22 statistically significant photometric sources are spectroscopically confirmed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/381/418
- Title:
- Wolf-Rayet population in NGC 1313
- Short Name:
- J/MNRAS/381/418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a VLT/FORS1 survey of Wolf-Rayet (WR) stars in the spiral galaxy NGC 1313. In total, 94 WR candidate sources have been identified from narrow-band imaging. Of these, 82 have been spectroscopically observed, for which WR emission features are confirmed in 70 cases, one of which also exhibits strong nebular HeII{lambda}4686 emission. We also detect strong nebular HeII{lambda}4686 emission within two other regions of NGC 1313, one of which is a possible supernova remnant. Nebular properties confirm that NGC 1313 has a metal content log(O/H)+12=8.23+/-0.06, in good agreement with previous studies. From continuum-subtracted H{alpha} images we infer a global star formation rate of 0.6M_{sun}/yr. Using template LMC WR stars, spectroscopy reveals that NGC 1313 hosts a minimum of 84 WR stars. Our census comprises 51 WN stars, including a rare WN/C transition star plus 32 WC stars. In addition, we identify one WO star which represents the first such case identified beyond the Local Group. The bright giant HII region PES 1, comparable in H{alpha} luminosity to NGC 595 in M 33, is found to host a minimum of 17 WR stars. The remaining photometric candidates generally display photometric properties consistent with WN stars, such that we expect a global WR population of ~115 stars with N(WR)/N(O)~0.01 and N(WC)/N(WN)~0.4.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A27
- Title:
- Wolf-Rayet stars in Large Magellanic Cloud
- Short Name:
- J/A+A/565/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars, although being important building blocks of galaxies, are still not fully understood. This especially holds true for Wolf-Rayet (WR) stars with their strong mass loss, whose spectral analysis requires adequate model atmospheres. Following our comprehensive studies of the WR stars in the Milky Way, we now present spectroscopic analyses of almost all known WN stars in the LMC. For the quantitative analysis of the wind-dominated emission-line spectra, we employ the Potsdam Wolf-Rayet (PoWR) model atmosphere code. By fitting synthetic spectra to the observed spectral energy distribution and the available spectra (ultraviolet and optical), we obtain the physical properties of 107 stars. We present the fundamental stellar and wind parameters for an almost complete sample of WN stars in the LMC. Among those stars that are putatively single, two different groups can be clearly distinguished. While 12% of our sample are more luminous than 10^6^L_{sun}_ and contain a significant amount of hydrogen, 88% of the WN stars, with little or no hydrogen, populate the luminosity range between log(L/L_{sun}_)=5.3...5.8.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/L20
- Title:
- Wolf 1061 velocities and planet candidates
- Short Name:
- J/ApJ/817/L20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use archival HARPS spectra to detect three planets orbiting the M3 dwarf Wolf 1061 (GJ 628). We detect a 1.36M_{Earth}_ minimum-mass planet with an orbital period P=4.888days (Wolf 1061b), a 4.25M_{Earth}_ minimum-mass planet with orbital period P=17.867days (Wolf 1061c), and a likely 5.21M_{Earth}_ minimum-mass planet with orbital period P=67.274days (Wolf 1061d). All of the planets are of sufficiently low mass that they may be rocky in nature. The 17.867day planet falls within the habitable zone for Wolf 1061 and the 67.274day planet falls just outside the outer boundary of the habitable zone. There are no signs of activity observed in the bisector spans, cross-correlation FWHMs, calcium H & K indices, NaD indices, or H{alpha} indices near the planetary periods. We use custom methods to generate a cross-correlation template tailored to the star. The resulting velocities do not suffer the strong annual variation observed in the HARPS DRS velocities. This differential technique should deliver better exploitation of the archival HARPS data for the detection of planets at extremely low amplitudes.
