- ID:
- ivo://CDS.VizieR/J/AJ/161/221
- Title:
- Photometry & spectroscopy of 4 binaries stars
- Short Name:
- J/AJ/161/221
- Date:
- 16 Mar 2022 11:53:19
- Publisher:
- CDS
- Description:
- We present the photometric and spectroscopic analysis of four W-UMa binaries J015829.5+260333 (hereinafter as J0158), J030505.1+293443 (hereinafter as J0305), J102211.7+310022 (hereinafter as J1022), and KW-Psc. The VRcIc band photometric observations are carried out with the 1.3m Devasthal Fast Optical Telescope (DFOT). For low-resolution spectroscopy, we used the 2m Himalayan Chandra Telescope (HCT) as well as the archival data from the 4m LAMOST survey. The systems J0158 and J0305 show a period increase rate of 5.26({+/-}1.72)x10^-7^days/yr and 1.78({+/-}1.52)x10^-6^days/yr, respectively. The period of J1022 is found to be decreasing with a rate of 4.22({+/-}1.67)x10^-6^days/yr. The period analysis of KW-Psc displays no change in its period. The PHOEBE package is used for the light-curve modeling and basic parameters are evaluated with the help of the GAIA parallax. The asymmetry of light curves is explained with the assumption of cool spots at specific positions on one of the components of the system. On the basis of temperatures, mass ratios, fill-out factors, and periods, the system J1022 is identified as a W-subtype system while the others show some mixed properties. To probe the chromospheric activities in these W-UMa binaries, their spectra are compared with the known inactive stars' spectra. The comparison shows emission in H{alpha}, H{beta}, and CaII. To understand the evolutionary status of these systems, the components are plotted in mass-radius and mass-luminosity planes with other well characterized binary systems. The secondary components of all the systems are away from ZAMS, which indicates that the secondary is more evolved than the primary component.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/823/58
- Title:
- Photo-reverberation mapping of 27 YSOs in LDN1688
- Short Name:
- J/ApJ/823/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Theoretical models and spectroscopic observations of newborn stars suggest that protoplanetary disks have an inner "wall" at a distance set by the disk interaction with the star. Around T Tauri stars, the size of this disk hole is expected to be on a 0.1au scale that is unresolved by current adaptive optics imaging, though some model-dependent constraints have been obtained by near-infrared interferometry. Here we report the first measurement of the inner disk wall around a solar-mass young stellar object, YLW 16B in the {rho} Ophiuchi star-forming region, by detecting the light-travel time of the variable radiation from the stellar surface to the disk. Consistent time lags were detected on two nights, when the time series in H (1.6{mu}m) and K (2.2{mu}m) bands were synchronized while the 4.5{mu}m emission lagged by 74.5+/-3.2s. Considering the nearly edge-on geometry of the disk, the inner rim should be 0.084au from the protostar on average, with an error of order 0.01au. This size is likely larger than the range of magnetospheric truncations and consistent with an optically and geometrically thick disk front at the dust sublimation radius at ~1500K. The widths of the cross-correlation functions between the data in different wavebands place possible new constraints on the geometry of the disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/L73
- Title:
- Photospheric fluxes at 24 and 70{mu}m
- Short Name:
- J/ApJ/700/L73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust in debris disks is generated by collisions among planetesimals. The existence of these planetesimals is a consequence of the planet-formation process, but the relationship between debris disks and planets has not been clearly established. Here we analyze Spitzer/MIPS 24 and 70um data for 150 planet-bearing stars, and compare the incidence of debris disks around these stars with a sample of 118 stars around which planets have been searched for, but not found. Together they comprise the largest sample ever assembled to deal with this question. The use of survival analysis techniques allows us to account for the large number of non-detections at 70um. We discovered 10 new debris disks around stars with planets and one around a star without known planets. We found that the incidence of debris disks is marginally higher among stars with planets, than among those without, and that the brightness of the average debris disk is not significantly different in the two samples. We conclude that the presence of a planet that has been detected via current radial velocity techniques is not a good predictor for the presence of a debris disk detected at infrared wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/497/497
- Title:
- Physical parameters from JHK flux
- Short Name:
- J/A+A/497/497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The effective temperature scale of FGK stars, especially at the lowest metallicities remains a major problem in the chemical abundance analysis of metal-poor stars. We present a new implementation of the infrared flux method (IRFM) using the 2MASS catalogue.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A141
- Title:
- Physical parameters of PMS in open clusters
- Short Name:
- J/A+A/531/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our aims are twofold: To determine the physical parameters of PMS members in young open clusters (YOCs), and to check and compare the performances of different model isochrones. We compare UBVRI photometric observations of eleven YOCs to theoretical isochrones in the photometric diagrams. The comparison simultaneously provides membership assignments for MS and PMS stars and estimates for the masses, ages, and spatial distribution of the candidate members. The relations found between the different cluster parameters show that the procedure applied to assign cluster membership, and to measure physical parameters for the selected members, is well founded.
- ID:
- ivo://CDS.VizieR/J/AJ/159/17
- Title:
- Physical properties of SFRs in NGC 3395/NGC 3396
- Short Name:
- J/AJ/159/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report long-slit spectroscopy of the early major merger galaxies NGC 3395/NGC 3396. The spectra are consistent with those for star-forming galaxies, but there is some indication of LINER-like active galactic nucleus activity in the center of NGC 3396. The total star formation rate in the regions observed is 2.83 M_{sun}_/yr, consistent with estimates for the entire galaxies. The highest abundances are in the centers of the galaxies, with the abundances decreasing with distance. There is a correlation between high abundance and high ionization parameter, both of which can be attributed to the presence of massive stars. Modeling with SB 99 indicates the star-forming regions are younger than 10 Myr. There are 1000-2000 WNL stars in the system, along with several thousand O stars, consistent with the ages of the star-forming regions. The highest electron densities are found in young regions with high star formation rates. The electron temperatures are higher than results for non-interacting galaxies, which is probably due to shock waves produced by the galaxy-galaxy interaction, the outflow of gas from massive stars, and/or collisions between gas clouds in the galaxies. There is star formation in the bridge of material between the galaxies. These regions are among the youngest in the system and have low abundances, suggesting the gas was pulled from the outer parts of the galaxies. X-ray point sources, probably high-mass X-ray binaries, are associated with several star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/539/A119
- Title:
- Pismis 24 stars with X-ray emission
- Short Name:
- J/A+A/539/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Circumstellar disks are expected to evolve quickly in massive young clusters harboring many OB-type stars. Two processes have been proposed to drive the disk evolution in such cruel environments: (1) gravitational interaction between circumstellar disks and nearby passing stars (stellar encounters), and (2) photoevaporation by UV photons from massive stars. The relative importance of both mechanisms is not well understood. Studies of massive young star clusters can provide observational constraints on the processes of driving disk evolution. We investigate the properties of young stars and their disks in the NGC 6357 complex, concentrating on the most massive star cluster within the complex: Pismis 24.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/154
- Title:
- Planck cold clump G108.37-01.06 YSO candidates
- Short Name:
- J/ApJ/864/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Planck Galactic Cold Clumps (PGCCs) are possible representations of the initial conditions and very early stages of star formation. With the objective of understanding better the star and star cluster formation, we probe the molecular cloud associated with PGCC G108.37-01.06 (hereafter PG108.3), which can be traced in a velocity range of -57 to -51km/s. The INT Photometric H{alpha} Survey images reveal H{alpha} emission at various locations around PG108.3, and optical spectroscopy of the bright sources in those zones of H{alpha} emission discloses two massive ionizing sources with spectral type O8-O9V and B1V. Using the radio continuum, we estimate ionizing gas parameters and find the dynamical ages of HII regions associated with the massive stars in the range of 0.5-0.75Myr. Based on the stellar surface density map constructed from the deep near-infrared Canada-France-Hawaii Telescope observations, we find two prominent star clusters in PG108.3; of these, the cluster associated with H ii region S148 is moderately massive (~240M_{sun}_). A careful inspection of James Clerk Maxwell telescope ^13^CO (3-2) molecular data exhibits that the massive cluster is associated with a number of filamentary structures. Several embedded young stellar objects (YSOs) are also identified in PG108.3 along the length and junction of filaments. We find evidence of a velocity gradient along the length of the filaments. Along with kinematics of the filaments and the distribution of ionized, molecular gas and YSOs, we suggest that the cluster formation is most likely due to the longitudinal collapse of the most massive filament in PG108.3.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A106
- Title:
- Planck submillimetre sources in Virgo Cluster
- Short Name:
- J/A+A/562/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We cross-correlate the Planck Catalogue of Compact Sources (PCCS) with the fully sampled 84deg^2^ Herschel Virgo Cluster Survey (HeViCS) fields. We search for and identify the 857 and 545GHz PCCS sources in the HeViCS fields by studying their FIR/submm and optical counterparts. We find 84 and 48 compact Planck sources in the HeViCS fields at 857 and 545GHz, respectively. Almost all sources correspond to individual bright Virgo Cluster galaxies. The vast majority of the Planck detected galaxies are late-type spirals, with the Sc class dominating the numbers, while early-type galaxies are virtually absent from the sample, especially at 545GHz. We compare the HeViCS SPIRE flux densities for the detected galaxies with the four different PCCS flux density estimators and find an excellent correlation with the aperture photometry flux densities, even at the highest flux density levels. We find only seven PCCS sources in the HeViCS fields without a nearby galaxy as obvious counterpart, and conclude that all of these are dominated by Galactic cirrus features or are spurious detections. No Planck sources in the HeViCS fields seem to be associated to high-redshift proto-clusters of dusty galaxies or strongly lensed submm sources. Finally, our study is the first empirical confirmation of the simulation-based estimated completeness of the PCCS, and provides a strong support of the internal PCCS validation procedure.
- ID:
- ivo://CDS.VizieR/J/AJ/154/134
- Title:
- Planetary-mass brown dwarfs in the Taurus SFR
- Short Name:
- J/AJ/154/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results from a survey for planetary-mass brown dwarfs in the Taurus star-forming region. We have identified brown dwarf candidates in Taurus using proper motions and photometry from several ground- and space- based facilities. Through spectroscopy of some of the more promising candidates, we have found 18 new members of Taurus. They have spectral types ranging from mid-M to early-L, and they include the four faintest known members in extinction-corrected K_s_, which should have masses as low as ~4-5 M_Jup_ according to evolutionary models. Two of the coolest new members (M9.25, M9.5) have mid-IR excesses that indicate the presence of disks. Two fainter objects with types of M9-L2 and M9-L3 also have red mid-IR colors relative to photospheres at =<L0, but since the photospheric colors are poorly defined at >L0, it is unclear whether they have excesses from disks. We also have obtained spectra of candidate members of the IC 348 and NGC 1333 clusters in Perseus that were identified by Luhman et al. Eight candidates are found to be probable members, three of which are among the faintest and least-massive known members of the clusters (~5 M_Jup_).
