- ID:
- ivo://CDS.VizieR/J/MNRAS/491/655
- Title:
- Photometry and spectroscopy of RN LMC 1968
- Short Name:
- J/MNRAS/491/655
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive review of all observations of the eclipsing recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a probable recurrence time of 6.2+/-1.2yr and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR photometry the light curve shows high variability right from the first observation around 2 d after eruption. Therefore no colour changes can be substantiated. Outburst spectra from 2016 and 1990 are very similar and are dominated by H and He lines longward of 2000{AA}. Interstellar reddening is found to be E(B-V)=0.07+/-0.01. The super soft X-ray luminosity is lower than the Eddington luminosity and the X-ray spectra suggest the mass of the white dwarf (WD) is larger than 1.3M_{sun}_. Eclipses in the light curve suggest that the system is at high orbital inclination. On day 4 after the eruption a recombination wave was observed in FeII ultraviolet absorption lines. Narrow-line components are seen after day 6 and explained as being due to reionization of ejecta from a previous eruption. The UV spectrum varies with orbital phase, in particular a component of the HeII 1640{AA} emission line, which leads us to propose that early-on the inner WD Roche lobe might be filled with a bound opaque medium prior to the re-formation of an accretion disc. Both this medium and the ejecta can cause the delay in the appearance of the soft X-ray source.
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- ID:
- ivo://CDS.VizieR/J/AJ/144/131
- Title:
- Photometry and spectroscopy of SN 2010jl
- Short Name:
- J/AJ/144/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive optical observations of a Type IIn supernova (SN IIn) 2010jl for the first 1.5years after its discovery. The UBVRI light curves demonstrated an interesting two-stage evolution during the nebular phase, which almost flatten out after about 90days from the optical maximum. SN 2010jl has one of the highest intrinsic H{alpha} luminosities ever recorded for an SN IIn, especially at late phase, suggesting a strong interaction of SN ejecta with the dense circumstellar material (CSM) ejected by the progenitor. This is also indicated by the remarkably strong Balmer lines persisting in the optical spectra. One interesting spectral evolution about SN 2010jl is the appearance of asymmetry of the Balmer lines. These lines can be well decomposed into a narrow component and an intermediate-width component. The intermediate-width component showed a steady increase in both strength and blueshift with time until t~400days after maximum, but it became less blueshifted at t~500days, when the line profile appeared relatively symmetric again. Owing to the fact that a pure reddening effect will lead to a sudden decline of the light curves and a progressive blueshift of the spectral lines, we therefore propose that the asymmetric profiles of H lines seen in SN 2010jl are unlikely due to the extinction by newly formed dust inside the ejecta, contrary to the explanation by some early studies. Based on a simple CSM-interaction model, we speculate that the progenitor of SN 2010jl may suffer a gigantic mass loss (~30-50M_{sun}_) a few decades before explosion. Considering a slow-moving stellar wind (e.g.,~28km/s) inferred for the preexisting, dense CSM shell and the extremely high mass-loss rate (1-2M_{sun}_/yr), we suggest that the progenitor of SN 2010jl might have experienced a red supergiant stage and may explode finally as a post-red supergiant star with an initial mass above 30-40M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/150/200
- Title:
- Photometry and spectroscopy of stars in Cz 30
- Short Name:
- J/AJ/150/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric and spectroscopic data of the old open cluster Czernik 30. Wide field BVI photometry allows us to correct for the high field contamination by statistical subtraction to produce a color-magnitude diagram (CMD) that clearly reveals the cluster sequence. From spectra of stars in the cluster field obtained with the Hydra spectrograph on the Wisconsin-Indiana-Yale-NOAO 3.5m telescope we determine a mean cluster velocity of +79.9+/-1.5km/s and provide membership information that helps further define the cluster giant branch and red clump. Stellar abundances for the brighter giants in the cluster indicate a mean metallicity of [Fe/H]=-0.2+/-0.15. Fitting theoretical isochrones to the CMD we determine the following properties of Czernik 30: age=2.8+/-0.3Gyr, (m-M)_v_=14.8+/-0.1, E(B-V)=0.24+/-0.06, and E(V-I)=0.36+/-0.04. Czernik 30 is an old, sub-solar metallicity cluster located at a Galactocentric radius of R_gc_~13.3kpc. Given its age and position just beyond the transition to a flat abundance gradient seen in the open cluster population, Czernik 30 provides an interesting target for future observations.
- ID:
- ivo://CDS.VizieR/J/AJ/147/104
- Title:
- Photometry and velocities of 1SWASP J093010A and B
- Short Name:
- J/AJ/147/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among quadruples or higher multiplicity stars, only a few doubly eclipsing binary systems have been discovered. They are important targets for understanding the formation and evolution of multiple stellar systems because we can obtain accurate stellar parameters from photometric and spectroscopic studies. We present the observational results of this kind of rare object, 1SWASP J093010.78+533859.5, for which the doubly eclipsing feature had been detected previously from the SuperWASP photometric archive. Individual point-spread function photometry for two objects with a separation of about 1.9" was performed for the first time in this study. Our time-series photometric data confirms the finding of Lohr et al. that the bright object A is an Algol-type detached eclipsing binary and the fainter B is a W UMa-type contact eclipsing. Using high-resolution optical spectra, we obtained well-defined radial velocity variations of system A. Furthermore, stationary spectral lines were detected that must have originated from a further, previously unrecognized stellar component. It was confirmed by the third object contribution from the light-curve analysis. No spectral feature of system B was detected, probably due to motion blur by long exposure times. We obtained the binary parameters and the absolute dimensions of systems A and B from light-curve synthesis with and without radial velocities, respectively. The primary and secondary components of system A have a spectral type of K1 and K5 main sequences, respectively. Two components of system B have nearly the same type of K3 main sequence. Light variations for both binaries are satisfactorily modeled by using two-spot models with one starspot on each component. We estimated the distances to systems A and B individually. Two systems may have similar distances of about 70 pc and seem to be gravitationally bound with a separation of about 130 AU. In conclusion, we suggest that 1SWASP J093010.78+533859.5 is a quintuple stellar system with a hierarchical structure of a triple system A(ab)c and a binary system B(ab).
- ID:
- ivo://CDS.VizieR/J/ApJ/679/1490
- Title:
- Photometry and Velocity of 3 {zeta} Aur binaries
- Short Name:
- J/ApJ/679/1490
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived new orbits for {zeta} Aur, 32 Cyg, and 31 Cyg with observations from the Tennessee State University (TSU) Automatic Spectroscopic Telescope, and used them to identify nonorbital velocities of the cool supergiant components of these systems. Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both {zeta} Aur and 32 Cyg, at a level and phasing roughly consistent with simple theory to first order, although they seem to require moderately large gravity darkening. We point out two fundamental questions in the interpretation of these stars: (1) whether it is appropriate to model the surface brightness as gravity darkening and (2) whether much of the nonorbital velocity structure may actually represent changes in the convective flows in the stars' atmospheres.
- ID:
- ivo://CDS.VizieR/J/ApJ/903/31
- Title:
- Photometry AT 2018hyz with Swift XRT, UVOT and Swope
- Short Name:
- J/ApJ/903/31
- Date:
- 11 Mar 2022 14:12:05
- Publisher:
- CDS
- Description:
- We present the multiwavelength analysis of the tidal disruption event (TDE) AT2018hyz (ASASSN-18zj). From follow-up optical spectroscopy, we detect the first unambiguous case of resolved double-peaked Balmer emission in a TDE. The distinct line profile can be well-modeled by a low eccentricity (e~0.1) accretion disk extending out to ~100Rp and a Gaussian component originating from non-disk clouds, though a bipolar outflow origin cannot be completely ruled out. Our analysis indicates that in AT2018hyz, disk formation took place promptly after the most-bound debris returned to pericenter, which we estimate to be roughly tens of days before the first detection. Redistribution of angular momentum and mass transport, possibly through shocks, must occur on the observed timescale of about a month to create the large H{alpha}-emitting disk that comprises <~5% of the initial stellar mass. With these new insights from AT2018hyz, we infer that circularization is efficient in at least some, if not all optically bright, X-ray faint TDEs. In these efficiently circularized TDEs, the detection of double-peaked emission depends on the disk inclination angle and the relative strength of the disk contribution to the non-disk component, possibly explaining the diversity seen in the current sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/198/1
- Title:
- Photometry catalogs for the Lockman Hole
- Short Name:
- J/ApJS/198/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broadband photometry and photometric redshifts for 187611 sources located in ~0.5deg^2^ in the Lockman Hole area. The catalog includes 388 X-ray-detected sources identified with the very deep XMM-Newton observations available for an area of 0.2deg^2^. The source detection was performed on the Rc-, z'-, and B-band images and the available photometry is spanning from the far-ultraviolet to the mid-infrared, reaching in the best-case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire data set allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which are active galactic nuclei (AGNs). For normal galaxies, comparing the photometric redshifts to the 253 available spectroscopic redshifts, we achieve an accuracy of {sigma}_{Delta}z/(1+z)_=0.036, with 12.6% outliers. For the X-ray-detected sources, compared to 115 spectroscopic redshifts, the accuracy is {sigma}_{Delta}z/(1+z)_=0.069, with 18.3% outliers, where the outliers are defined as sources with |z_phot_-z_spec_|>0.15x(1+z_spec_).
- ID:
- ivo://CDS.VizieR/J/ApJ/742/113
- Title:
- Photometry during the 2010 eruption of U Sco
- Short Name:
- J/ApJ/742/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The eruption of the recurrent nova U Scorpii on 2010 January 28 is now the all-time best observed nova event. We report 36776 magnitudes throughout its 67 day eruption, for an average of one measure every 2.6 minutes. This unique and unprecedented coverage is the first time that a nova has had any substantial amount of fast photometry. With this, two new phenomena have been discovered: the fast flares in the early light curve seen from days 9-15 (which have no proposed explanation) and the optical dips seen out of eclipse from days 41-61 (likely caused by raised rims of the accretion disk occulting the bright inner regions of the disk as seen over specific orbital phases). The expanding shell and wind cleared enough from days 12-15 so that the inner binary system became visible, resulting in the sudden onset of eclipses and the turn-on of the supersoft X-ray source. On day 15, a strong asymmetry in the out-of-eclipse light points to the existence of the accretion stream. The normal optical flickering restarts on day 24.5. For days 15-26, eclipse mapping shows that the optical source is spherically symmetric with a radius of 4.1R_{sun}_. For days 26-41, the optical light is coming from a rim-bright disk of radius 3.4R_{sun}_. For days 41-67, the optical source is a center-bright disk of radius 2.2R_{sun}_. Throughout the eruption, the colors remain essentially constant. We present 12 eclipse times during eruption plus five just after the eruption.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1825
- Title:
- Photometry identification of cool white dwarfs
- Short Name:
- J/AJ/128/1825
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the use of a narrowband DDO51 filter for photometric identification of cool white dwarfs. We report photometric observations of 30 known cool white dwarfs with temperatures ranging from 10,000K down to very cool temperatures (<=3500K). Follow-up spectroscopic observations of a sample of objects selected using this filter and our photometric observations show that DDO51 filter photometry can help select cool white dwarf candidates for follow-up multiobject spectroscopy by rejecting 65% of main-sequence stars with the same broadband colors as the cool white dwarfs. This technique is not selective enough to efficiently feed single-object spectrographs. We present the white dwarf cooling sequence using this filter. Our observations show that very cool white dwarfs form a sequence in the r-DDO versus r-z color-color diagram and demonstrate that significant improvements are needed in white dwarf model atmospheres.
- ID:
- ivo://CDS.VizieR/J/A+A/389/439
- Title:
- Photometry in field of RX J004404.8+411820
- Short Name:
- J/A+A/389/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose the first association of an optical counterpart with a luminous supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July 1991. The PSPC position is at 1.644 angular distance from a candidate nova in outburst in September of 1990. This is interesting because the incidence of classical novae among supersoft X-ray sources is an open question. The proposed optical counterpart was measured at R~=17.7 in September of 1990, and it had faded to R>19.2 when it was observed again after 70 days. The light curve was too sparsely monitored for definite conclusions on the speed class of the nova. No other variable objects with V<23.5 were found in the ROSAT spatial error box. We evaluate that the probability that a classical or recurrent nova was in outburst in the ROSAT error box in the few years preceding the observation is very small, so the proposed identification is meaningful. We also show evidence that the associated supersoft X-ray source turned off in the third year after the outburst.
