- ID:
- ivo://CDS.VizieR/J/ApJS/96/605
- Title:
- Far UV Stellar Photometry
- Short Name:
- J/ApJS/96/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 541 objects in a field centered near zeta Scorpii is presented. These data were extracted from electrographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with lambda_eff = 1375 A and lambda_eff = 1781 A. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. Fifty-eight percent of the ultraviolet objects were identified with visible stars using the SIMBAD database while another 40% of the objects are blends of early type stars too close together to separate with our resolution. Our photometry is compared with that from the TD-1, OAO 2, and ANS satellites and the S201 (Apollo 16) far-ultraviolet camera and found to agree at the level of a few tenths of a magnitude. Unlike previous studies, almost half of the identified visual counterparts to the ultraviolet objects are early B stars. A plot of distance modulus against ultraviolet color excess reveals a significant population of stars with strong ultraviolet excesses.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/104/101
- Title:
- Far-UV stellar photometry
- Short Name:
- J/ApJS/104/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Far-ultraviolet photometry is presented for 121 objects in a 20deg diameter field centered on Rho Oph and for 649 objects in a field covering the Galactic center. Broadband magnitudes with effective wavelengths of 1375A and 1781A are given. The Galactic center field overlaps two fields which were discussed in an earlier paper. Eighty- eight percent of the ultraviolet objects in the Rho Oph field were identified with visible stars using the SIMBAD database, while only 9% of the objects are blends of early-type stars too close together to separate with our resolution. The photometric calibration was studied in detail, and corrections for nonlinearity were derived for the fields analyzed earlier as well as those discussed here. For stars in common between the Galactic center field and the previous fields, a comparison of the magnitudes yielded estimates of the internal errors of the magnitudes of sigma_1375=0.13mag and sigma_1781=0.21mag. A collated list of stars in the fields covering the Galactic center and incorporating the revised calibration is presented and compared with the S201 data of the same region. The properties of the sample of ultraviolet objects in the Rho Oph field are briefly commented upon.
- ID:
- ivo://CDS.VizieR/J/PAZh/37/120
- Title:
- Fast optical variability of SS 433
- Short Name:
- J/PAZh/37/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the variability of the optical flux from the peculiar Galactic source SS 433 based on observations with the Russian-Turkish 1.5-m telescope. We describe in detail the technique of high-quality photometric measurements with a time resolution of 0.3-1s using an ordinary CCD. Through test observations of non-variable stars, we show that atmospheric turbulence introduces no significant distortions into the light curves. Therefore, such data are well suited for studying the aperiodic variability of various objects.
- ID:
- ivo://CDS.VizieR/J/A+A/384/491
- Title:
- Fast-rotating nearby solar-type stars. I.
- Short Name:
- J/A+A/384/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velocities, vsini, Li abundances and X-ray luminosities and investigate the single or binary nature of the sample stars. Such a careful analysis of our sample shows a large fraction of binaries (~62%) and of young single disk stars. In particular, at least 9 stars can be considered bona-fide PMS or ZAMS objects, and 30 stars are identified as SBs for the first time. Information on the presence of Ca II K emission and on optical variability is given for some of the stars of the sample. The photometry has been obtained at the European Southern Observatory (ESO-La silla, Chile) during several observing runs (19/11-03/12 1993, 24/11-04/12 1994, 15-28/01/1995 and 1-12/10/1995), by using the 50cm ESO telescope. The figures were published in paper II.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1205
- Title:
- Fast transients in the Fornax cluster
- Short Name:
- J/ApJ/682/1205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity gap between novae (M_R_<=-10) and supernovae (M_R_>=-14) has been well known since the pioneering research of Zwicky and Hubble. Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae. Here we present the results of a B-band survey of 23 member galaxies of the Fornax Cluster, performed at the Las Campanas 2.5m Irenee du Pont telescope. Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of M_B_=-9.3mag. We provide a detailed assessment of the transient detection efficiency and the resulting upper limits on the event rate as function of peak magnitude. Further, we discuss the discoveries of five previously unknown foreground variables which we identified as two flare stars, two W UMa-type eclipsing binaries and a candidate {delta} Scuti/SX Phe star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/313/641
- Title:
- FAUST observations in 4th Galactic Quadrant
- Short Name:
- J/MNRAS/313/641
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UV observations of FAUST are analysed in four sky fields (Dor, Cen, M81 and Tel), located in the general direction of the Fourth Galactic Quadrant, where 777 UV sources are detected, about 50% more than detected originally by Bowyer et al. (1993ApJ...415..875B). Ground-based objective-prism information for two of the fields were used to select the best-matching optical objects with which to identify the UV sources. Using this, and correlations with existing catalogues, reliable identifications are presented for about 75% of the sources. Most of the remaining sources have assigned optical counterparts but, lacking additional information, we offer only plausible identifications. FAUST is a wide-field telescope (7.6{deg} diameter) designed to image diffuse and point sources in the wavelength range 140-180nm. The experiment, the mission and the data are described in a previous paper by Bowyer et al., 1993ApJ...415..875B .
- ID:
- ivo://CDS.VizieR/J/MNRAS/324/580
- Title:
- FAUST sources in NGC 4038-39 and 6752 direction
- Short Name:
- J/MNRAS/324/580
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Analysis of ultraviolet (UV) observations with the FAUST shuttle-borne telescope toward the Antennae and NGC 6752 celestial regions resulted in the detection of 46 and 221 candidate sources respectively, for a signal-to-noise ratio of 8. We discuss the source detection process and the identification of UV sources with optical counterparts. Using correlations with existing catalogues, we present reliable identifications for approximately 60 per cent of the sources. We find that most identified objects are B, A and F stars. The remaining identified objects are galaxies, a white dwarf in a binary system, and two K-type stars. Nearly all of the remaining unidentified objects have assigned optical counterparts but, lacking additional information, we give these only as best estimates. With help from new diagnostic diagrams, we suggest that these unclassified objects are main-sequence (or giant) stars within the local spiral arm or halo; or other hot evolved objects within the local spiral arm. We discuss the nature of the objects found and compare our results with those predicted from spectral and Galactic models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/332/441
- Title:
- FAUST UV sources towards Ophiuchus
- Short Name:
- J/MNRAS/332/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour-colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars. Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos/Tycho (<I/239>) information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A35
- Title:
- FBS 0117+396 pulsating sdB star photometry
- Short Name:
- J/A+A/559/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims to discover subdwarf-B stars with massive compact companions such as overmassive white dwarfs (M>1.0M_{sun}_), neutron stars or black holes. From the 127 subdwarfs with substantial radial-velocity variations discovered in the initial survey, a number of interesting objects have been selected for extensive follow-up. After an initial photometry run with BUSCA revealed that FBS0117+396 is photometrically variable both on long and short timescales, we chose it as an auxiliary target during a 6-night multi-color photometry run with Ultracam. Spectroscopy was obtained at a number of observatories in order to determine the binary period and obtain a radial-velocity amplitude. After establishing an orbital period of P=0.252d, and removing the signal associated with the irradiated hemisphere of the M-dwarf companion, we were able to detect ten pulsation periods in the Fourier spectrum of the light curve. Two pulsation modes are found to have short periods of 337 and 379s, and at least eight modes are found with periods between 45-min and 2.5h. This establishes that FBS0117+396 is an sdB+dM reflection binary, in which the primary is a hybrid pulsator, and the first one found with this particular melange of flavours.
- ID:
- ivo://CDS.VizieR/J/other/Ap/45.322
- Title:
- FBS 13th list of late M and carbon stars
- Short Name:
- J/other/Ap/45.32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The thirteenth list of faint late M and carbon type stars detected on the plates of the First Byurakan Spectral Sky Survey in zone +1{deg}<={delta}<=+13{deg} covering about 3118 sq. degrees is presented. From 285 stars, 161 are newly detected objects: they are 17 carbon stars, 25 carbon star candidates, and 117 M-type stars. The spectral type of two objects is assumed to be between M8 - M9 or late N-subtypes. Among 161 objects, 85 (66 PSC + 19 FSC) are unclassified IRAS sources. Accurate positions, spectral classes, red magnitudes, and color indices are given using several astronomical databases. Finding charts from DSS are given for the most interesting objects.
