- ID:
- ivo://CDS.VizieR/J/A+A/329/579
- Title:
- uvby photometry of theta CrB
- Short Name:
- J/A+A/329/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present differential uvby photometry of {theta} CrB obtained in 1994 and 1995, complemented by Balmer line spectroscopy. This star has been constant during this period, showing no short term periodic variability with an amplitude greater than 0.005mag., nor long term variations greater than 0.01mag. The lack of variability is associated with an inactive phase of the Be star, in which no emission features are present in the spectra. The only remarkable event observed was a fading episode on JD 2449779, with an amplitude of about 0.02 magnitudes in all bandpasses and duration of 0.2-0.3 days.
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- ID:
- ivo://CDS.VizieR/J/other/JAD/23.1
- Title:
- uvby photometry of theta Tucanae
- Short Name:
- J/other/JAD/23.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- theta Tucanae (HR 139, V=6.11, A7 IV) is a binary with a delta Scuti primary that was the subject of several photometric monitoring campaigns during the 1970s and again in the 1990s. The data presented in this paper were collected during an observing campaign from mid-September to the end of October 1993 at ESO La Silla, Chile, using the simultaneous Stroemgren uvby photometer at the SAT telescope during 25 partial nights. We present a time series of 1432 four-colour extinction-corrected magnitudes in the SAT instrumental system. This collection of data forms a homogeneous and contiguous dataset, obtained in one single instrumental setup, at one single observing site using one single observing protocol, and with centralized data reduction.
4343. uvby photometry of V Crt
- ID:
- ivo://CDS.VizieR/J/A+AS/101/49
- Title:
- uvby photometry of V Crt
- Short Name:
- J/A+AS/101/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+AS/128/251
- Title:
- uvby photometry of V3903 Sgr
- Short Name:
- J/A+AS/128/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Complete uvby light curves of the young detached double-lined massive O-type eclipsing binary V3903 Sagittarii, obtained from 1989 to 1994, are presented. The observations were obtained at two different sites and a discussion of the characteristics of both data sets is included.
- ID:
- ivo://CDS.VizieR/J/A+A/389/931
- Title:
- uvby photometry & radial velocities of R 81
- Short Name:
- J/A+A/389/931
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1.dat contains the photometric uvby data of the eclipsing binary hypergiant R81 (B2.5 Ia-O) of the Large Magellanic Cloud. The data have been obtained with the Danish 50 cm telescope at ESO, La Silla, and cover more than one orbital cycle of 74.59 days. File table2.dat contains radial velocity measurements of photospheric lines of this star. The spectra have been obtained simultaneously with the photometry. The Feros spectrograph at the ESO 1.52m telescope was used. The quoted radial velocities are averages over the best photospheric lines.
- ID:
- ivo://CDS.VizieR/J/MNRAS/363/529
- Title:
- uvby, UBV and radial velocity of WW Aur
- Short Name:
- J/MNRAS/363/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- WW Aurigae is a detached eclipsing binary composed of two metallic- lined A-type stars orbiting each other every 2.5 days. We have determined the masses and radii of both components to accuracies of 0.4% and 0.6%, respectively. From a cross-correlation analysis of high-resolution spectra we find masses of 1.964+/-0.007M_{sun}_ for the primary star and 1.814+/-0.007M_{sun}_ for the secondary star. From an analysis of photoelectric uvby and UBV light curves we find the radii of the stars to be 1.927+/-0.011R_{sun}_ and 1.841+/-0.011R_{sun}_, where the uncertainties have been calculated using a Monte Carlo algorithm. Fundamental effective temperatures of the two stars have been derived, using the Hipparcos parallax of WW Aur and published ultraviolet, optical and infrared fluxes, and are 7960+/-420 and 7670+/-410K. The masses, radii and effective temperatures of WW Aur are only matched by theoretical evolutionary models for a fractional initial metal abundance, Z, of approximately 0.06 and an age of roughly 90Myr. This seems to be the highest metal abundance inferred for a well-studied detached eclipsing binary, but we find no evidence that it is related to the metallic-lined nature of the stars. The circular orbit of WW Aur is in conflict with the circularization timescales of both the Tassoul and the Zahn tidal theories and we suggest that this is due to pre-main-sequence evolution or the presence of a circular orbit when the stars were formed.
- ID:
- ivo://CDS.VizieR/J/A+AS/123/529
- Title:
- UV-excess quasar candidates around NGC 450
- Short Name:
- J/A+AS/123/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a survey for moderately bright quasars performed in a 20.6-square-degree field around the galaxy NGC 450. The quasar candidates we re-selected on the basis of their ultraviolet excess: by comparative visual inspection of the double image of each single object on a U/B dual-exposure Schmidt photographic plate, 95 primary and 45 secondary quasar candidates were selected on the basis of their U image being too bright. The spectroscopic identification of the primary candidates led to the discovery of 59 bona fide quasars (out of which 6 were previously known). The Palomar Schmidt plate was digitised using the MAMA measuring machine and the outcoming data reduced using ad hoc procedures. A photometric calibration allowed us to derive values for the limiting magnitudes and for the U-B index selection threshold of the survey. A catalogue containing 60 quasars is presented with accurate positions, magnitudes and additional information such as redshifts. We studied the spatial distribution of the objects and detected, for the quasars of our sample, a significant deviation from randomness in the form of a propensity to cluster in pairs on the celestial sphere with a typical scale of about 10arcmin. We also formally detected a tendency towards a 3-D clustering, but this result is induced by a single pair of quasars. A forthcoming paper will deal with a similar work performed in a field around NGC 520; the latter field is located directly to the North of the present one and slightly overlaps it.
- ID:
- ivo://CDS.VizieR/J/MNRAS/406/420
- Title:
- UV/far-IR data of infrared excess sources
- Short Name:
- J/MNRAS/406/420
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the nature of Infrared Excess sources (IRX), which are proposed as candidates for luminous [LX(2-10keV)>10^43^erg/s] Compton thick (NH>2x10^24^cm^-2^) QSOs at z~~2. Lower redshift, z~~1, analogues of the distant IRX population are identified by first redshifting to z=2 the spectral energy distributions (SEDs) of all sources with secure spectroscopic redshifts in the AEGIS (6488) and the GOODS-North (1784) surveys and then selecting those that qualify as IRX sources at that redshift. A total of 19 galaxies are selected. The mean redshift of the sample is z~~1. We do not find strong evidence for Compton thick QSOs in the sample. For nine sources with X-ray counterparts, the X-ray spectra are consistent with Compton thin active galactic nucleus (AGN). Only three of them show tentative evidence for Compton thick obscuration. The SEDs of the X-ray undetected population are consistent with starburst activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/879/131
- Title:
- UV-FIR obs. of post-starburst galaxies & dust masses
- Short Name:
- J/ApJ/879/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive dust masses (M_dust_) from the spectral energy distributions of 58 post-starburst galaxies (PSBs). There is an anticorrelation between specific dust mass (M_dust_/M_*_) and the time elapsed since the starburst ended, indicating that dust was either destroyed, expelled, or rendered undetectable over the ~1Gyr after the burst. The M_dust_/M_*_ depletion timescale, 205_-37_^+58^Myr, is consistent with that of the CO-traced M_H2_/M_*_, suggesting that dust and gas are altered via the same process. Extrapolating these trends leads to the M_dust_/M_*_ and M_H2_/M_*_ values of early-type galaxies (ETGs) within 1-2Gyr, a timescale consistent with the evolution of other PSB properties into ETGs. Comparing Mdust and M_H2_ for PSBs yields a calibration, log M_H2_=0.45logM_dust_+6.02, that allows us to place 33 PSBs on the Kennicutt-Schmidt (KS) plane, {Sigma}SFR-{Sigma}M_H2_. Over the first ~200-300Myr, the PSBs evolve down and off of the KS relation, as their star formation rate (SFR) decreases more rapidly than M_H2_. Afterwards, M_H2_ continues to decline whereas the SFR levels off. These trends suggest that the star formation efficiency bottoms out at 10^-11^/yr and will rise to ETG levels within 0.5-1.1Gyr afterwards. The SFR decline after the burst is likely due to the absence of gas denser than the CO-traced H2. The mechanism of the M_dust_/M_*_ and M_H2_/M_*_ decline, whose timescale suggests active galactic nucleus/low-ionization nuclear emission-line region feedback, may also be preventing the large CO-traced molecular gas reservoirs from collapsing and forming denser star-forming clouds.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/13
- Title:
- UV-IR photometry of SMC stars
- Short Name:
- J/ApJ/771/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nature of the progenitors of Type Ia supernovae (SNe Ia) is still a mystery. While plausible candidates are known for both the single-degenerate and double-degenerate models, the observed numbers fall significantly short of what is required to reproduce the SNe Ia rate. Some of the most promising single-degenerate Type Ia progenitors are recurrent novae and super-soft sources (SSS). White dwarfs (WDs) with higher mass transfer rates can also be SN Ia progenitors. For these rapidly accreting white dwarfs (RAWDs), more material than is needed for steady burning accretes on the WD, and extends the WD's photosphere. Unlike SSS, such objects will likely not be detectable at soft X-ray energies, but will be bright at longer wavelengths, such as the far-ultraviolet (UV). Possible examples include LMC N66 and the V Sagittae stars. We present a survey using multi-object spectrographs looking for RAWDs in the central core of the Small Magellanic Cloud (SMC), from objects selected to be bright in the far-UV and with blue far UV-V colors. While we find some unusual objects, and recover known planetary nebula and Wolf-Rayet (WR) stars, we detect no candidate RAWD. The upper limits from this non-detection depend on our expectations of what an RAWD should look like, as well assumptions about the internal extinction of the SMC. Assuming they resemble LMC N66 or fainter versions of WR stars we set an upper limit of 10-14 RAWDs in the SMC. However, our survey is unlikely to detect objects like V Sge, and hence we cannot set meaningful upper limits if RAWDs generally resemble V Sge.
