- ID:
- ivo://CDS.VizieR/J/ApJS/91/625
- Title:
- ROSAT survey of the Pleiades
- Short Name:
- J/ApJS/91/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep ROSAT images of three regions within the Pleiades open cluster. We have detected 317 X-ray sources in these ROSAT PSPC images, 171 of which we associate with certain or probable members of the Pleiades cluster. We detect nearly all Pleiades members with spectral types later than G0 and within 25 arcminutes of our three field centers where our sensitivity is highest. This has allowed us to derive for the first time the luminosity function for the G, K, and M dwarfs of an open cluster without the need to use statistical techniques to account for the presence of upper limits in the data sample. Because of our high X-ray detection frequency down to the faint limit of the optical catalog, we suspect that some of our unidentified X-ray sources are previously unknown, very low-mass members of the Pleiades.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/371/833
- Title:
- ROSAT Ultra Deep Survey
- Short Name:
- J/A+A/371/833
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ROSAT Ultra Deep Survey in the Lockman Hole consists of a sample of 94 X-ray sources reaching a limiting flux of 1.2x10-15erg/s/cm^2^ in the 0.5-2.0keV energy band. About 90% of the X-ray sources have been spectroscopically identified using low-resolution Keck spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/595/1206
- Title:
- ROSAT view of Hipparcos F stars
- Short Name:
- J/ApJ/595/1206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For a set of 11900 F stars that have uvby photometry and are in the Hipparcos (Cat. <I/239>) catalog, we have found 1980 X-ray counterparts (~17%) in the ROSAT All-Sky Surveys (RASS, Cat. <IX/10> and <IX/29>). In this paper we analyze X-ray properties of these ROSAT F stars and compare that sample with the entire set of our F stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/260/77
- Title:
- ROSAT Wide Field Camera EUV Bright Sources
- Short Name:
- J/MNRAS/260/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/554/202
- Title:
- ROSAT X-ray observations of M81
- Short Name:
- J/ApJ/554/202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the analysis of deep ROSAT HRI and PSPC observations of the spiral galaxy M81. The inferred total (0.5-2keV band) luminosity of M81 is ~3x10^40^ergs/s, excluding the contribution from identified interlopers found within the D_25_ ellipse. The nucleus of the galaxy alone accounts for about 65% of this luminosity. The rest is due to 26 other X-ray sources (contributing ~10%) and to apparently diffuse emission, which is seen across much of the galactic disk and is particularly bright in the bulge region around the nucleus. Spectral analysis further gives evidence for a soft component, which can be characterized by a two-temperature optically thin plasma with temperature at ~0.15 and 0.60keV and an absorption of the galactic foreground only. These components, accounting for ~13% of the X-ray emission from the region, apparently arise in a combination of hot gas and faint discrete sources. We find interesting spatial coincidences of luminous (10^37^-10^40^ergs/s) and variable X-ray sources with shock-heated optical nebulae. Three of them are previously classified as supernova remnant candidates. The other one is far off the main body of M81 but is apparently associated with a dense H I concentration produced most likely by the tidal interactions of the galaxy with its companions. These associations suggest that such optical nebulae may be powered by outflows from luminous X-ray binaries, which are comparable to, or more luminous than, Galactic "microquasars."
- ID:
- ivo://CDS.VizieR/J/A+A/388/100
- Title:
- ROSAT X-ray sources in LMC. II.
- Short Name:
- J/A+A/388/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 200 X-ray sources from a sample of spectrally hard ROSAT PSPC sources, given in the catalog of Haberl & Pietsch (1999, Cat. <J/A+AS/139/277>), and observed in a ~60 square degree field of the LMC during several archival pointed observations with a wide range of exposure times have been reanalyzed. For these sources accurate count rates and hardness ratios have been recalculated. In comparison to Haberl & Pietsch (1999, Cat. <J/A+AS/139/277>) we used merged data from all available observations and we derived average source parameters by investigating each source individually. From a simulation power-law spectral tracks have been derived in the HR1-HR2 plane and ~170 sources have been classified as background X-ray sources or as LMC X-ray binaries. 80% of the spectrally hard X-ray sources with more than 50 observed counts have been found to be consistent with background X-ray sources and 20% with LMC X-ray binaries (53 sources with AGN and 15 with X-ray binaries).
- ID:
- ivo://CDS.VizieR/J/AJ/110/1229
- Title:
- ROSAT X-ray survey in NGC 6475
- Short Name:
- J/AJ/110/1229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A ROSAT X-ray survey, with complementary optical photometry, of the open cluster NGC 6475 has enabled the detection of ~50 late-F to K0 and ~70 K/M dwarf new candidate members, providing the first reliable detection of low-mass stars in this low galactic latitude, 220Myr old cluster. The X-ray observations reported here have a typical limiting sensitivity of L_X_ ~ 10^29^erg/s. The detection frequency of early type cluster members is consistent with the hypothesis that the X-ray emitting early type stars are binary systems with an unseen, low-mass secondary producing the X-rays. The ratio between X-ray and bolometric luminosity among NGC 6475 members saturates at a spectral-type/color which is intermediate between that in much younger and in much older clusters, consistent with rotational spindown of solar-type stars upon their arrival on the ZAMS. The upper envelope of X-ray luminosity as a function of spectral type is comparable to that of the Pleiades, with the observed spread in X-ray luminosity among low-mass members being likely due to the presence of binaries and relatively rapid rotators. However, the list of X-ray selected candidate members is likely biased against low-mass, slowly rotating single stars. While some preliminary spectroscopic information is given in an appendix, further spectroscopic observations of the new candidate members will aid in interpreting the coronal activity among solar-type NGC 6475 members and their relation to similar stars in older and younger open clusters.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/465
- Title:
- ROSAT XUV Pointed Phase Source Catalogue
- Short Name:
- J/A+AS/114/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of XUV sources from observations by the Wide Field Camera (WFC) on ROSAT during the pointed phase. The ROSAT WFC is a telescope sensitive in the extreme UV range (17-210eV) which observes in parallel with the ROSAT X-Ray Telescope (XRT). The 5916 pointed observations processed are from the calibration and verification phase in June 1990 and from the period 9 Feb. 1991 to 15 July 1994. The catalogue contains 1022 independent source detections which correspond to 328 individual sources, many of which have been observed repeatedly. Each observation was done with one of four filters S1, S2, P1 and P2. Of the 328 sources 113 are new sources (they are not listed in the "2RE" catalogue) and 274 have been identified with optical counterparts. The catalogue contains coordinates, observed count rates, normalized source count rates and the proposed optical counterpart with its spectral class.
- ID:
- ivo://CDS.VizieR/J/other/RAA/9.1035
- Title:
- RV light curves of 1RXS J201607.0+251645
- Short Name:
- J/other/RAA/9.10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 1RXS J201607.0+251645 is identified as an eclipsing binary. We present preliminary observations in the V band with the 0.6-m telescope for three years and extensive observations in the V and R bands with the 0.8-m telescope for six nights, respectively. The light curve of the system is EB type. Five light minimum times were obtained and the orbital period of 0.388058d(+/-0.00044d) is determined.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A135
- Title:
- RX J0503.9-2854 spectral energy distribution
- Short Name:
- J/A+A/598/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the density of the interstellar medium (ISM) is very low, and thus the contamination of the stellar spectrum almost negligible. This allows us to identify many metal lines in a wide wavelength range from the extreme ultraviolet to the near infrared. In previous spectral analyses, many metal lines in the ultraviolet spectrum of RX J0503.9-2854 have been identified. A complete line list of observed and identified lines is presented here. We compared synthetic spectra that had been calculated from model atmospheres in non-local thermodynamical equilibrium, with observations. In total, we identified 1272 lines (279 of them were newly assigned) in the wavelength range from the extreme ultraviolet to the near infrared. 287 lines remain unidentified. A close inspection of the EUV shows that still no good fit to the observed shape of the stellar continuum flux can be achieved although He, C, N, O, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Cr, Ni Zn, Ga, Ge, As, Kr, Zr, Mo, Sn, Xe, and Ba are included in the stellar atmosphere models.