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- 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/A+A/544/L3
- Title:
- Photometry of the double eclipsing binary CzeV343
- Short Name:
- J/A+A/544/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of a possible new quadruple system composed of two unresolved eclipsing binaries (EBs), CzeV343 (V~13.5mag). We obtained photometric observations of CzeV343 that completely cover the two orbital periods and we successfully model the light curves as the sum of two detached EBs. The two orbital periods, 1.20937 and 0.80693-days, are within 0.1% of a 3:2 ratio. We speculate that this might be the result of Kozai cycles and tidal friction evolution of quadruple systems.
- 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/704/898
- Title:
- Photometry of the Hercules dwarf galaxy
- Short Name:
- J/ApJ/704/898
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present imaging of the recently discovered Hercules Milky Way satellite and its surrounding regions to study its structure, star formation history and to thoroughly search for signs of disruption. We robustly determine the distance, luminosity, size, and morphology of Hercules utilizing a bootstrap approach to characterize our uncertainties. We derive a distance to Hercules via a comparison to empirical and theoretical isochrones, finding a best match with the isochrone of M92, which yields a distance of 133+/-6kpc. As previous studies have found, Hercules is very elongated, with {epsilon}=0.67+/-0.03 and a half-light radius of r_h_~230pc. Using the color-magnitude-fitting package StarFISH, we determine that Hercules is old (>12Gyr) and metal-poor ([Fe/H]~-2.0), with a spread in metallicity, in agreement with previous spectroscopic work. This result is robust with respect to slight variations in the distance to Hercules and mismatches between the observed Hercules color-magnitude diagram and theoretical isochrones. We infer a total absolute magnitude of M_V_=-6.2+/-0.4. Our innovative search for external Hercules structure both in the plane of the sky and along the line of sight yields some evidence that Hercules is embedded in a larger stream of stars. A clear stellar extension is seen to the northwest with several additional candidate stellar overdensities along the position angle of Hercules out to ~35' (~1.3kpc).
- 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/A+AS/108/571
- Title:
- Photometry of the SMC cluster NGC 330
- Short Name:
- J/A+AS/108/571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- 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.