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- ID:
- ivo://CDS.VizieR/J/A+A/659/A8
- Title:
- First study of four doubly eclipsing systems
- Short Name:
- J/A+A/659/A8
- Date:
- 16 Mar 2022 07:25:25
- Publisher:
- CDS
- Description:
- We present the discovery and the very first analysis of four stellar systems showing two periods of eclipses, that are the objects classified as doubly eclipsing systems. Some of them were proved to orbit each other thanks to their eclipse-timing-variations (ETVs) of both pairs, hence they really constitute rare quadruples with two eclipsing pairs. Some of them do not, as we are still waiting for more data to detect their mutual movement. Their light curves and period changes were analysed. All of them are detached and near-contact, but none of them contact; moreover, to our knowledge none of these stars can be considered as blend of two spatially unresolved close components on the sky. These systems are CzeV2647 (0.5723296+0.9637074 days), proved to orbit with 4.5-year periodicity; CzeV1645 (1.0944877+1.6594641 days), with a rather questionable detection of ETV; CzeV3436 (0.6836870+0.3833930 days); and, finally, OGLE SMC-ECL-1758 (0.9291925+3.7350826 days), proved to move on its 30-year orbit. Even more surprising is the fact that most of these systems show the ratio of their two orbital periods close to coupling near some resonant values of small integers, namely CzeV2647, with only 1% from 3:5 resonance, CzeV1645 1% from 2:3 resonance, and OGLE SMC-ECL-1758 with only 0.49% from 1:4 resonance. The nature of these near-resonant states still remains a mystery.
- ID:
- ivo://irsa.ipac/USNO/Catalog/URAT1
- Title:
- First USNO Robotic Astrometric Telescope Catalog
- Short Name:
- URAT1
- Date:
- 01 Oct 2018 20:27:21
- Publisher:
- NASA/IPAC Infrared Science Archive
- Description:
- URAT is a follow-up project to the successful UCAC project using the same astrograph but with a much larger focal plane array and a bandpass shifted further to the red. Longer integration times and more sensitive, backside CCDs allowed for a substantial increase in limiting magnitude, resulting in about 4-fold increase in the average number of stars per square degree as compared to UCAC. Additional observations with an objective grating largely extend the dynamic range to include observations of stars as bright as about 3rd magnitude. Multiple sky overlaps per year result in a significant improvement in positional precision as compared to UCAC.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2097
- Title:
- FIRST "Winged" and X-shaped radio source candidates
- Short Name:
- J/AJ/133/2097
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A small number of double-lobed radio galaxies (17 from our own census of the literature) show an additional pair of low surface brightness "wings," thus forming an overall X-shaped appearance. Using the VLA FIRST survey database, we are compiling a large sample of winged and X-shaped radio sources for such studies. As a first step toward this goal, an initial sample of 100 new candidate objects of this type are presented in this paper.
- ID:
- ivo://CDS.VizieR/J/ApJS/185/32
- Title:
- First-year SDSS-II SN results
- Short Name:
- J/ApJS/185/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04<z<0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. Within the framework of the MLCS2K2 light-curve fitting method, we use the SDSS-II SN sample to infer the mean reddening parameter for host galaxies, R_V_=2.18+/-0.14_stat_+/-0.48_syst_, and find that the intrinsic distribution of host-galaxy extinction is well fitted by an exponential function, P(A_V_)=exp(-A_V_/{tau}_V_), with {tau}_V_=0.334+/-0.088mag. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey (SNLS), the Hubble Space Telescope (HST), and a compilation of Nearby SN Ia measurements. A new feature in our analysis is the use of detailed Monte Carlo simulations of all surveys to account for selection biases, including those from spectroscopic targeting.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A199
- Title:
- Fit parameters & ephemerides of 650 mCP stars
- Short Name:
- J/A+A/622/A199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic, chemically peculiar stars are known for exhibiting surface abundance inhomogeneities (chemical spots) that lead to photometric and spectroscopic variability with the rotation period. It is commonly assumed that the surface structures are causally connected with the global magnetic field that dominates the photospheric and subphotospheric layers of these stars. As a rule, the observed magnetic fields show a simple dipole-like geometry, with the magnetic axis being noncollinear to the rotational one. The present study aims at detecting underlying patterns in the distribution of photometric spots in a sample of 650 magnetic, chemically peculiar stars and examines their link to the magnetic field topology. Photometric time-series observations from the ASAS-3 archive were employed to inspect the light-curve morphology of our sample stars and divide them into representative classes described using a principal component analysis. Theoretical light curves were derived from numerous simulations assuming different spot parameters and following the symmetry of a simple dipole magnetic field. These were subsequently compared with the observed light curves. The results from our simulations are in contradiction with the observations and predict a much higher percentage of double-wave light curves than is actually observed. We thereby conclude that the distribution of the chemical spots does not follow the magnetic field topology, which indicates that the role of the magnetic field in the creation and maintenance of the surface structures may be more subsidiary than what is predicted by theoretical studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/151
- Title:
- Fitted jet components in BL Lacertae
- Short Name:
- J/ApJ/787/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at a position angle of -166.6{deg} that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical two-dimensional relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock (RCS). Because of this, and the close analogy to the jet feature HST-1 in M87, we identify the standing feature in BL Lac as an RCS. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in which the slowest moving feature is a slow-mode wave, and the fastest feature is a fast-mode wave. In the model, the beam has Lorentz factor {Gamma}_beam_^gal^~3.5 in the frame of the host galaxy and the fast mode wave has Lorentz factor {Gamma}_Fwave_^beam^~1.6 in the frame of the beam. This gives a maximum apparent speed for the moving features, {beta}_app_=v_app_/c=10. In this model the Lorentz factor of the pattern in the galaxy frame is approximately three times larger than that of the beam itself.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A118
- Title:
- Fitted orbits and parameters of 51 Eridani b
- Short Name:
- J/A+A/624/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 51 Eridani observations were performed with the VLT exoplanet imager SPHERE for 3 years in order to monitor the orbital motion of the known giant planet and refine its orbital parameters. We carried out an orbital analysis using three complementary approaches (LSMC, MCMC, Bayesian rejection sampling) and found broadly similar results. The data suggest a period of 23-49yr (i.e. semi-major axis of 10-16au), an inclination of 126-147{deg}, an eccentricity of 0.30-0.55, and an argument at periastron of 57-121{deg} (mod 180{deg}). The time at periastron and the longitude of node exhibit bimodal distributions.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A95
- Title:
- Fitted proper motions for the DR solution
- Short Name:
- J/A+A/559/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose new estimates of the secular aberration drift, mainly due to the rotation of the Solar System about the Galactic center, based on up-to-date VLBI observations and and improved method of outlier elimination. We fit degree-2 vector spherical harmonics to extragalactic radio source proper motion field derived from geodetic VLBI observations spanning 1979-2013. We pay particular attention to the outlier elimination procedure to remove outliers from (i) radio source coordinate time series and (ii) the proper motion sample. We obtain more accurate values of the Solar system acceleration compared to those in our previous paper. The acceleration vector is oriented towards the Galactic center within ~7{deg}. The component perpendicular to the Galactic plane is statistically insignificant. We show that an insufficient cleaning of the data set can lead to strong variations in the dipole amplitude and orientation, and statistically biased results.
- ID:
- ivo://CDS.VizieR/J/MNRAS/399/432
- Title:
- Fitted UBV magnitude for MS stars
- Short Name:
- J/MNRAS/399/432
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We fit the colour-magnitude diagrams of stars between the zero-age main-sequence and terminal-age main sequence in young clusters and associations. The ages we derive are a factor of 1.5-2 longer than the commonly used ages for these regions, which are derived from the positions of pre-main-sequence stars in colour-magnitude diagrams. From an examination of the uncertainties in the main-sequence and pre-main-sequence models, we conclude that the longer age scale is probably the correct one, which implies that we must revise upwards the commonly used ages for young clusters and associations. Such a revision would explain the discrepancy between the observational lifetimes of protoplanetary discs and theoretical calculations of the time to form planets. It would also explain the absence of clusters with ages between 5 and 30Myr.