- ID:
- ivo://CDS.VizieR/J/ApJ/812/133
- Title:
- 1889-2015 photometry of Stingray nebula
- Short Name:
- J/ApJ/812/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Up until around 1980, the Stingray was an ordinary B1 post-AGB star, but then it suddenly sprouted bright emission lines like in a planetary nebula (PN), and soon after this the Hubble Space Telescope (HST) discovered a small PN around the star, so apparently we have caught a star in the act of ionizing a PN. We report here on a well-sampled light curve from 1889 to 2015, with unique coverage of the prior century plus the entire duration of the PN formation plus three decades of its aftermath. Surprisingly, the star anticipated the 1980s ionization event by declining from B=10.30 in 1889 to B=10.76 in 1980. Starting in 1980, the central star faded fast, at a rate of 0.20mag/yr, reaching B=14.64 in 1996. This fast fading is apparently caused by the central star shrinking in size. From 1994 to 2015, the V-band light curve is almost entirely from the flux of two bright [OIII] emission lines from the unresolved nebula, and it shows a consistent decline at a rate of 0.090mag/yr. This steady fading (also seen in the radio and infrared) has a timescale equal to that expected for ordinary recombination within the nebula, immediately after a short-duration ionizing event in the 1980s. We are providing the first direct measure of the rapidly changing luminosity of the central star on both sides of a presumed thermal pulse in 1980, with this providing a strong and critical set of constraints, and these are found to sharply disagree with theoretical models of PN evolution.
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- ID:
- ivo://CDS.VizieR/II/45
- Title:
- Photometry of strong CN stars
- Short Name:
- II/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A group of 185 late G and K giants, selected from the US Naval Observatory Catalog of Photoelectric Observations (Cat. II/4) because they had Ultraviolet deficiences, were observed with the intermediate band photometric system of the David Dunlap Observatory (defined by McClure and van den Bergh 1968AJ.....73..313M). The DDO photometry is included in Cat. II/17.
- ID:
- ivo://CDS.VizieR/J/A+A/359/597
- Title:
- Photometry of SX Phe stars in globular clusters
- Short Name:
- J/A+A/359/597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present for the first time a catalogue of SX Phe-type pulsating variables in globular clusters. In addition, SX Phe variables discovered in the Carina dwarf galaxy and other ones probably belonging to the Sagittarius dwarf galaxy are included. This catalogue is intended to be an up-dated list of all the SX Phe stars, in globular clusters and galaxies, known until now, covering information published up to January, 2000. In summary, 149 variables are presented in our list for SX Phe-type variables belonging to 18 globular clusters and 2 galaxies. Some relevant distributions are also shown. The analysis of metal abundances and mean periods shows that both parameters are correlated in the sense that the periods of the variables are longer as the metallicity of the stellar system is higher.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/1027
- Title:
- Photometry of the afterglow of GRB 130831A
- Short Name:
- J/MNRAS/455/1027
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet the nature and physical properties of their energy sources are far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray observations of GRB 130831A obtained by Swift, Chandra, Skynet, Reionization And Transients Infra-Red camera, Maidanak, International Scientific Optical-Observation Network, Nordic Optical Telescope, Liverpool Telescope and Gran Telescopio Canarias. This burst shows a steep drop in the X-ray light curve at ~10^5^ s after the trigger, with a power-law decay index of {alpha}~6. Such a rare behaviour cannot be explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at 10^5^ s, must be of "internal origin", produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must produce the X-ray flux for ~1 d in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease, and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after ~10^5^ s can be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta, and compare it with the energy of the associated supernova, SN 2013 fu.
- ID:
- ivo://CDS.VizieR/J/ApJS/192/12
- Title:
- Photometry of the blazar PKS 0537-441
- Short Name:
- J/ApJS/192/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a large collection of photometric data on the blazar PKS 0537-441 in the VRIJHK bands taken in 2004-2009. At least three flare-like episodes with months duration and >3mag amplitude are apparent. The spectral energy distribution is consistent with a power law, and no indication of a thermal component is found. We searched for short timescale variability, and an interesting event was identified in the J band, with a duration of ~25 minutes.
- ID:
- ivo://CDS.VizieR/J/PAZh/22/764
- Title:
- Photometry of the globular cluster NGC 6139
- Short Name:
- J/PAZh/22/764
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photographic BV photometry has been performed for stars in the southern globular cluster NGC 6139. Equatorial coordinates have been determined for the ten variables recognized in NGC 6139.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/L33
- Title:
- Photometry of the Ic supernova PTF12gzk
- Short Name:
- J/ApJ/760/L33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our light curves show a rise of 0.8mag within 2.5hr. Power-law fits (f(t){prop.to}(t-t_0_)^n^) to these data constrain the explosion date to within one day. We cannot rule out a quadratic fireball model, but higher values of n are possible as well for larger areas in the fit parameter space. Our bolometric light curve and a dense spectral sequence are used to estimate the physical parameters of the exploding star and of the explosion. We show that the photometric evolution of PTF12gzk is slower than that of most SNe Ic. The high ejecta expansion velocities we measure (~30000km/s derived from line minima four days after explosion) are similar to the observed velocities of broad-lined SNe Ic associated with gamma-ray bursts (GRBs) rather than to normal SN Ic velocities. Yet, this SN does not show the persistent broad lines that are typical of broad-lined SNe Ic. The host-galaxy characteristics are also consistent with GRB-SN hosts, and not with normal SN Ic hosts. By comparison with the spectroscopically similar SN 2004aw, we suggest that the observed properties of PTF12gzk indicate an initial progenitor mass of 25-35M_{sun}_ and a large ((5-10)x10^51^erg) kinetic energy, the later being close to the regime of GRB-SN properties.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/120
- Title:
- Photometry of the tidal disruption event PS18kh
- Short Name:
- J/ApJ/880/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of PS18kh, a tidal disruption event discovered at the center of SDSS J075654.53+341543.6 (d~322Mpc) by the Pan-STARRS Survey for Transients. Our data set includes pre-discovery survey data from Pan-STARRS, the All-sky Automated Survey for Supernovae, and the Asteroid Terrestrial-impact Last Alert System as well as high-cadence, multiwavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from T~12000K to T~25000K and it peaked at a luminosity of L~8.8x10^43^erg/s. PS18kh radiated E=(3.45+/-0.22)x10^50^erg over the period of observation, with (1.42+/-0.20)x10^50^erg being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked H{alpha} emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the H{alpha} line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from r_in_~60r_g_ to an outer radius of r_out_~1400r_g_ and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/46
- Title:
- Photometry of the transient event iPTF16fnl
- Short Name:
- J/ApJ/844/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based and Swift observations of iPTF16fnl, a likely tidal disruption event (TDE) discovered by the intermediate Palomar Transient Factory (iPTF) survey at 66.6Mpc. The light curve of the object peaked at an absolute mag M_g_=-17.2. The maximum bolometric luminosity (from optical and UV) was L_p_~(1.0+/-0.15)x10^43^erg/s, an order of magnitude fainter than any other optical TDE discovered so far. The luminosity in the first 60 days is consistent with an exponential decay, with L{propto}e^-(t-t_0_)/{tau}^, where t_0_=57631.0 (MJD) and {tau}~15 days. The X-ray shows a marginal detection at L_X_=2.4_-1.1_^1.9^x10^39^erg/s (Swift X-ray Telescope). No radio counterpart was detected down to 3{sigma}, providing upper limits for monochromatic radio luminosities of {nu}L_{nu}_<2.3x10^36^erg/s and {nu}L_{nu}_<1.7x10^37^erg/s (Very Large Array, 6.1 and 22GHz). The blackbody temperature, obtained from combined Swift UV and optical photometry, shows a constant value of 19000K. The transient spectrum at peak is characterized by broad HeII and H{alpha} emission lines, with FWHMs of about 14000km/s and 10000km/s, respectively. HeI lines are also detected at {lambda}{lambda}5875 and 6678. The spectrum of the host is dominated by strong Balmer absorption lines, which are consistent with a post-starburst (E+A) galaxy with an age of ~650Myr and solar metallicity. The characteristics of iPTF16fnl make it an outlier on both luminosity and decay timescales, as compared to other optically selected TDEs. The discovery of such a faint optical event suggests a higher rate of tidal disruptions, as low-luminosity events may have gone unnoticed in previous searches.
- ID:
- ivo://CDS.VizieR/J/AJ/158/186
- Title:
- Photometry of 12 totally eclipsing W UMa stars
- Short Name:
- J/AJ/158/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric observations of 12 totally eclipsing W UMa binaries (NSVS 3325547, V646 Lac, V1320 Cas, V539 Dra, V816 Cep, NSVS 9045055, V1115 Cas, V902 Cep, V596 Peg, NSVS 1768818, V619 Peg, and NSVS 3198272) are presented. We found that the longer (in phase units) the flat eclipses are, the smaller the mass ratios (or the reciprocal values) are. The mass ratios of five targets turned out close to the lower-mass ratio limit. We found that the periods of V1115 Cas and V646 Lac increase, while that of V596 Peg decreases. Masses, radii, and luminosities of the target components were calculated by the light-curve solutions and Gaia distances. In order to perform more reliable statistical analysis of the results we added to the sample of 12 targets from this paper another 29 totally eclipsing W UMa stars studied by us earlier. As a result we found the following trends: (a) the radius and luminosity of the target components increase with their mass but the dependencies are different from those of main-sequence (MS) stars; (b) the temperatures of stellar components whose masses are above 1 M_{sun}_ tend to be lower than those of the corresponding MS stars, while the temperatures of stellar components whose masses are below 1 M_{sun}_ tend to be higher than those of the corresponding MS stars; (c) there is no relationship between the fillout factor and mass ratio; and (d) 11 of the 41 targets are of A subtype, 24 are of W subtype, and 6 systems are with equal-temperature components.
