- ID:
- ivo://CDS.VizieR/J/AJ/143/28
- Title:
- Analysis of B6-A9 stars from INES UV spectra
- Short Name:
- J/AJ/143/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Main-sequence (MS) and giant late-B and early-A type stars are the best targets for searching for nearby interstellar (IS) SiIV and CIV resonance lines because they are not able to produce them, either in atmospheric layers or in their circumstellar environment, and because many stars of these spectral types are nearby and located in the local interstellar medium (LISM). In addition, the use of certain stars hotter than B6 can lead to misinterpretations (e.g., alpha Arae). This work analyzes the reliable Short-Wavelength Prime (SWP) high-resolution UV spectra of 558 B6-A9 type stars observed by the International Ultraviolet Explorer at distances lower than 400pc from the Sun. For the first time, this work utilizes the entire INES database to extract stellar and IS information in a systematic way from homogeneous data. Stars were classified into seven groups: normal (MS and subgiant), giant, peculiar, emission line, Algols, pre-main sequence or Herbig Ae/Be, and shell stars. Only 10 normal stars, located beyond 90pc, show weak SiIV and CIV absorptions and are clustered around the direction of Sco-Cen, while 85 located closer than 90pc, as well as another 89 beyond 90pc, do not show any absorptions at all.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/700/1173
- Title:
- Analysis of broad-line regions in AGNs
- Short Name:
- J/ApJ/700/1173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A two-component model for the broad-line region (BLR) of active galactic nuclei (AGNs) has been suggested for many years but not widely accepted. This model indicates that the broad line can be described with the superposition of two Gaussian components (very broad Gaussian component (VBGC) and intermediate Gaussian component (IMGC)) which are from two physically distinct regions, i.e., very broad line region (VBLR) and intermediate line region. We select a Sloan Digital Sky Survey sample to further confirm this model and give a detailed analysis of the geometry, density, and evolution of these two regions.
- ID:
- ivo://CDS.VizieR/J/A+A/492/277
- Title:
- Analysis of Collinder 69 stars with VOSA
- Short Name:
- J/A+A/492/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The physical properties of almost any kind of astronomical object can be derived by fitting synthetic spectra or photometry extracted from theoretical models to observational data. We want to develop an automatic procedure to perform this kind of fitting to a relatively large sample of members of a stellar association and apply this methodology to the case of Collinder 69. We combine the multiwavelength data of our sources and follow a work-flow to derive the physical parameters of the sources. The key step of the work-flow is performed by a new VO-tool, VOSA. All the steps in this process are done in a VO environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/153
- Title:
- Analysis of Fermi GRB data. IV. Spectral lags
- Short Name:
- J/ApJ/865/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with logE_p_{propto}k_E_log(t+t_0_) (^{tau}{propto}k_^{tau}logE), where E_p_ is the peak photon energy in the radiation spectrum, t+t_0_ is the observer time relative to the beginning of pulse -t0, and ^{tau} is the spectral lag of photons with energy E with respect to the energy band 8-25keV. For H2S and H2S-dominated-tracking pulses, a weak correlation between k_^{tau}/W and kE is found, where W is the pulse width. We also study the spectral lag behavior with peak time t_pE_ of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with logt_pE_{propto}k_tp_logE. It is found that k_tp_ is correlated with kE. We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately high-{sigma} outflow.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/2202
- Title:
- Analysis of {gamma}-ray bursts
- Short Name:
- J/MNRAS/418/2202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To find out the astrophysical processes responsible for gamma-ray burst (GRB), it is crucial to discover and understand the relations between their observational properties. This work was performed in the GRB rest frames using a sample of 62 long Swift GRBs with known redshifts. Following the earlier analysis of the correlation between afterglow luminosity (L^*^a) and break time (T^*^a), we extend it to correlations between the afterglow and the prompt emission GRB physical parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/143/39
- Title:
- Analysis of hot Jupiters in Kepler Q2
- Short Name:
- J/AJ/143/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the results of searching the Kepler Q2 public data set for the secondary eclipses of 76 hot Jupiter planet candidates from the list of 1235 candidates published by Borucki et al., 2011, Cat. J/ApJ/736/19. This search has been performed by modeling both the Kepler pre-search data conditioned light curves and new light curves produced via our own photometric pipeline. We derive new stellar and planetary parameters for each system, while calculating robust errors for both. We find 16 systems with 1{sigma}-2{sigma}, 14 systems with 2{sigma}-3{sigma}, and 6 systems with >3{sigma} confidence level secondary eclipse detections in at least one light curve produced via the Kepler pre-search data conditioned light curve or our own pipeline; however, results can vary depending on the light curve modeled and whether eccentricity is allowed to vary or not. We estimate false alarm probabilities of 31%, 10%, and 6% for the 1{sigma}-2{sigma}, 2{sigma}-3{sigma}, and >3{sigma} confidence intervals, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/155/196
- Title:
- Analysis of K2 LCs for members of USco & {rho} Oph
- Short Name:
- J/AJ/155/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of K2 light curves (LCs) for candidate members of the young Upper Sco (USco) association (~8 Myr) and the neighboring {rho} Oph embedded cluster (~1 Myr). We establish ~1300 stars as probable members, ~80% of which are periodic. The phased LCs have a variety of shapes which can be attributed to physical causes ranging from stellar pulsation and stellar rotation to disk-related phenomena. We identify and discuss a number of observed behaviors. The periods are ~0.2-30 days with a peak near 2 days and the rapid period end nearing breakup velocity. M stars in the young USco region rotate systematically faster than GK stars, a pattern also present in K2 data for the older Pleiades and Praesepe systems. At higher masses (types FGK), the well-defined period-color relationship for slowly rotating stars seen in the Pleiades and Praesepe systems is not yet present in USco. Circumstellar disks are present predominantly among the more slowly rotating M stars in USco, with few disks in the subday rotators. However, M dwarfs with disks rotate faster on average than FGK systems with disks. For four of these disked M dwarfs, we provide direct evidence for disk locking based on the K2 LC morphologies. Our preliminary analysis shows a relatively mass-independent spin-up by a factor of ~3.5 between USco and the Pleiades, then mass-dependent spin-down between Pleiades and Praesepe.
- ID:
- ivo://CDS.VizieR/J/ApJ/571/665
- Title:
- Analysis of the Ly{alpha} forest at z=0-5. V.
- Short Name:
- J/ApJ/571/665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Paper III (Bechtlod et al., 2002, Cat. <J/ApJS/140/143>) of our series, "A Uniform Analysis of the Ly{alpha} Forest at z=0-5", we presented a set of 270 quasar spectra from the archives of the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). A total of 151 of these spectra, yielding 906 lines, are suitable for using the proximity effect signature to measure J({nu}_0_), the mean intensity of the hydrogen-ionizing background radiation field, at low redshift.
- ID:
- ivo://CDS.VizieR/J/AJ/155/34
- Title:
- Analysis of the NIR spectra of neighboring L dwarfs
- Short Name:
- J/AJ/155/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Discrepancies between competing optical and near-infrared (NIR) spectral typing systems for L dwarfs have motivated us to search for a classification scheme that ties the optical and NIR schemes together, and addresses complexities in the spectral morphology. We use new and extant optical and NIR spectra to compile a sample of 171 L dwarfs, including 27 low-gravity {beta} and {gamma} objects, with spectral coverage from 0.6-2.4 {mu}m. We present 155 new low-resolution NIR spectra and 19 new optical spectra. We utilize a method for analyzing NIR spectra that partially removes the broad-band spectral slope and reveals similarities in the absorption features between objects of the same optical spectral type. Using the optical spectra as an anchor, we generate near-infrared spectral average templates for L0-L8, L0-L4{gamma}, and L0-L1{beta} type dwarfs. These templates reveal that NIR spectral morphologies are correlated with the optical types. They also show the range of spectral morphologies spanned by each spectral type. We compare low-gravity and field-gravity templates to provide recommendations on the minimum required observations for credibly classifying low-gravity spectra using low-resolution NIR data. We use the templates to evaluate the existing NIR spectral standards and propose new ones where appropriate. Finally, we build on the work of Kirkpatrick et al. to provide a spectral typing method that is tied to the optical and can be used when only H or K band data are available. The methods we present here provide resolutions to several long-standing issues with classifying L dwarf spectra and could also be the foundation for a spectral classification scheme for cloudy exoplanets.
- ID:
- ivo://CDS.VizieR/VIII/86
- Title:
- Analysis of the RC catalog sample.
- Short Name:
- VIII/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of paper I: 432 radio sources of the RC catalog produced in 1980-1985 at RATAN-600 radio telescope based on a deep survey of a sky strip centered on the declination of the SS433 source are identified in the region overlapping with FIRST and SDSS surveys (about 132{deg}^2^ large). The NVSS catalog was used as the reference catalog for refining the coordinates of the radio sources. The morphology is found for about 75% of the objects of the sample and the ratio of single, double and multicomponent radio sources is computed based on FIRST radio maps. The 74, 365, 1400, and 4850MHz data of the VLSS, TXS, NVSS, FIRST, and GB6 catalogs are used to analyze the shape of the spectra.
