- ID:
- ivo://CDS.VizieR/J/ApJS/136/631
- Title:
- IUE absorption toward 164 early-type stars
- Short Name:
- J/ApJS/136/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of Galactic interstellar AlIII, SiIV, and CIV absorption recorded in high-resolution archival ultraviolet spectra of 164 hot early-type stars observed by the International Ultraviolet Explorer (IUE) satellite. The objects studied were drawn from the list of hot stars scheduled to be observed with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite as part of observing programs designed to investigate absorption by OVI in the Galactic disk and halo. Multiple IUE echelle-mode integrations have been combined to produce a single ultraviolet (1150-1900{AA}) spectrum of each star with a spectral resolution of ~25km/s (FWHM). Selected absorption-line profiles are presented for each star along with plots of the apparent column density per unit velocity for each line of the AlIII, SiIV, and CIV doublets. We report absorption-line equivalent widths, absorption velocities, and integrated column densities based on the apparent optical depth method of examining interstellar absorption lines. We also determine column densities and Doppler parameters from single-component curve-of-growth analyses. The scientific analysis of these observations will be undertaken after the FUSE satellite produces similar measurements for absorption by interstellar OIV, FeIII, SIII, and other ions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/93/211
- Title:
- IUE survey of H I Ly{alpha} absorption. I.
- Short Name:
- J/ApJS/93/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure Galactic interstellar neutral hydrogen column densities by analyzing archival interstellar Ly{alpha} absorption line data toward 554 B2 and hotter stars observed at high resolution with the IUE satellite. This study more than doubles the number of lines of sight with measures of N(H I) based on Ly{alpha}. We have included the scattered light background correction algorithm of Bianchi and Bohlin (1984A&A...134...31B) in our data reduction. We use the correlation between the Balmer discontinuity [c_1_] index and the stellar Ly{alpha} absorption in order to assess the effects of stellar Ly alpha contamination. Approximately 40% of the B stars with measured [c_1_] index, exhibit serious stellar Ly{alpha} contamination. Table 1 contains the derived values of the interstellar N(H I) for 393 stars with at most small amounts of stellar contamination. Table 2 lists the observed values of total N(H I) for 161 stars with suspected stellar Ly alpha contamination and/or uncertain stellar parameters.
- ID:
- ivo://CDS.VizieR/J/AcA/54/347
- Title:
- IVB mag of LMC ellipsoidal variables
- Short Name:
- J/AcA/54/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the OGLE-II and OGLE-III photometry of red giants in the Large Magellanic Cloud to select and study objects revealing ellipsoidal variability. We detected 1546 candidates for long period ellipsoidal variables and 121 eclipsing binary systems with clear ellipsoidal modulation.
- ID:
- ivo://CDS.VizieR/J/AJ/149/125
- Title:
- Iybvu photometry and CCD spectroscopy of RX Gem
- Short Name:
- J/AJ/149/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained full-orbit Iybvu intermediate-band photometry and CCD spectroscopy of the long-period Algol eclipsing binary RX Geminorum. Photometric solutions using the Wilson-Devinney code give a gainer rotation (hotter, mass-accreting component) about 15 times the synchronous rate. We describe a simple technique to detect departures from uniform rotation of the hotter component. These binaries radiate double-peaked H{alpha} emission from a low-mass accretion disk around the gainer. We used an approximate non-LTE disk code to predict models in fair agreement with observations, except in the far wings of the emission profile, where the star-inner disk boundary layer emits extra radiation. Variations in H{alpha} emission derive from modulations in the transfer rate. A study of times of minima during the 20th century suggests that a perturbing third body is present near RX Gem.
- ID:
- ivo://CDS.VizieR/J/AJ/152/182
- Title:
- iz follow-up photometry of HAT-P-65 and HAT-P-66
- Short Name:
- J/AJ/152/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of the transiting exoplanets HAT-P-65b and HAT-P-66b, with orbital periods of 2.6055 and 2.9721 days, masses of 0.527+/-0.083M_J_ and 0.783+/-0.057M_J_, and inflated radii of 1.89+/-0.13R_J_ and 1.59_-0.10_^+0.16^R_J_, respectively. They orbit moderately bright (V=13.145+/-0.029 and V=12.993+/-0.052) stars of mass 1.212+/-0.050M_{Sun}_ and 1.255_-0.054_^+0.107^M_{Sun}_. The stars are at the main-sequence turnoff. While it is well known that the radii of close-in giant planets are correlated with their equilibrium temperatures, whether or not the radii of planets increase in time as their hosts evolve and become more luminous is an open question. Looking at the broader sample of well-characterized close-in transiting giant planets, we find that there is a statistically significant correlation between planetary radii and the fractional ages of their host stars, with a false-alarm probability of only 0.0041%. We find that the correlation between the radii of planets and the fractional ages of their hosts is fully explained by the known correlation between planetary radii and their present-day equilibrium temperatures; however, if the zero-age main-sequence equilibrium temperature is used in place of the present-day equilibrium temperature, then a correlation with age must also be included to explain the planetary radii. This suggests that, after contracting during the pre-main-sequence, close-in giant planets are reinflated over time due to the increasing level of irradiation received from their host stars. Prior theoretical work indicates that such a dynamic response to irradiation requires a significant fraction of the incident energy to be deposited deep within the planetary interiors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/1034
- Title:
- IZJHKL' photometry of NGC 6611
- Short Name:
- J/MNRAS/392/1034
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6611 is the massive young cluster (2-3Myr) that ionizes the Eagle Nebula. We present very deep photometric observations of the central region of NGC 6611 obtained with the Hubble Space Telescope and the following filters: ACS/WFC F775W and F850LP and NIC2 F110W and F160W, loosely equivalent to ground-based IZJH filters. This survey reaches down to I~26mag. We construct the initial mass function (IMF) from ~1.5M_{sun}_ well into the brown dwarf regime (down to ~0.02M_{sun}_). We have detected 30-35 brown dwarf candidates in this sample. The low-mass IMF is combined with a higher-mass IMF constructed from the ground-based catalogue from Oliveira et al. We compare the final IMF with those of well-studied star-forming regions: we find that the IMF of NGC 6611 more closely resembles that of the low-mass star-forming region in Taurus than that of the more massive Orion Nebula Cluster. We conclude that there seems to be no severe environmental effect in the IMF due to the proximity of the massive stars in NGC 6611.
- ID:
- ivo://CDS.VizieR/J/A+A/448/189
- Title:
- IzJHK photometry of IC4665
- Short Name:
- J/A+A/448/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the young (30-100Myr) open cluster IC4665 with the aim to determine the shape of the mass function well into the brown dwarf regime. We photometrically select 691 low-mass and 94 brown dwarf candidate members over an area of 3.82 square degrees centred on the cluster. K-band follow-up photometry and Two-Micron All-Sky Survey (<II/246>) data allow a first filtering of contaminant objects from our catalogues. A second filtering is performed for the brightest stars using proper motion data provided by the Tycho-2 (<I/259>) and UCAC2 (<I/289>) public catalogues. Contamination by the field population for the lowest mass objects is estimated using same latitude control fields. We fit observed surface densities of various cluster populations with King profiles and find a consistent tidal radius of 1.0 degree. The presence of possible mass segregation is discussed. In most respects investigated, IC4665 is similar to other young open clusters of similar age: (1) an estimate of the mass function in the low-mass regime and crossing the hydrogen burning limit results in a power law description with slope -0.6, (2) a fraction of BD to total members between 10-19%, (3) a cusp in the mass function is seen at about the substellar boundary, (4) the best-fit lognormal function to the full mass distribution shows an average member mass of 0.32M_{sun}_ if IC4665 has an age of 50Myr.
- ID:
- ivo://CDS.VizieR/J/A+A/450/147
- Title:
- IzJHKs photometry of Collinder 359
- Short Name:
- J/A+A/450/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first deep, optical, wide-field imaging survey of the young open cluster Collinder 359, complemented by near-infrared follow-up observations. This study is part of a large programme aimed at examining the dependence of the mass function on environment and time. We have surveyed 1.6 square degrees in the cluster, in the I and z filters, with the CFH12K camera on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection limits in both filters of 22.0 and 24.0mag, respectively. Based on their location in the optical (I-z,I) colour-magnitude diagram, we have extracted new cluster member candidates in Collinder 359 spanning 1.3-0.03M_{sun}_, assuming an age of 60Myr and a distance of 450pc for the cluster. We have used the 2MASS database as well as our own near-infrared photometry to examine the membership status of the optically-selected cluster candidates. Comparison of the location of the most massive members in Collinder 359 in a (B-V,V) diagram with theoretical isochrones suggests that Collinder 359 is older than Alpha Per but younger than the Pleiades. We discuss the possible relationship between Collinder 359 and IC 4665 as both clusters harbour similar parameters, including proper motion, distance, and age.
- ID:
- ivo://CDS.VizieR/J/A+A/522/A112
- Title:
- i'z' photometry of L5 and later dwarf candidates
- Short Name:
- J/A+A/522/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to recent and ongoing large scale surveys, hundreds of brown dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam camera on the Canada-France-Hawaii Telescope. Our objectives are to find ultracool brown dwarfs and to constrain the field brown-dwarf luminosity function and the mass function from a large and homogeneous sample of L and T dwarfs. We identify candidates in CFHT/MegaCam i' and z' images and follow them up with pointed near infrared (NIR) imaging on several telescopes. Halfway through our survey we found ~50 T dwarfs and ~170 L or ultra cool M dwarfs drawn from a larger sample of 1400 candidates with typical ultracool dwarfs i'-z' colours, found in 780 square degrees.
- ID:
- ivo://CDS.VizieR/J/A+A/400/891
- Title:
- IZ photometry of Pleiades brown dwarfs
- Short Name:
- J/A+A/400/891
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 6.4 square degrees imaging survey of the Pleiades cluster in the I and Z-bands. The survey extends up to 3{deg} from the cluster center and is 90% complete down to I~=22. It covers a mass range from 0.03M_{sun}_ to 0.48M_{sun}_ and yields 40 brown dwarf candidates (BDCs) of which 29 are new. The spatial distribution of BDCs is fitted by a King profile in order to estimate the cluster substellar core radius. The Pleiades mass function is then derived across the stellar-substellar boundary and we find that, between 0.03M_{sun}_ and 0.48M_{sun}_, it is well represented by a single power-law, dN/dM{prop.to}M^-{alpha}^, with an index alpha=0.60+/-0.11. Over a larger mass domain, however, from 0.03M_{sun}_ to 10M_{sun}_, the mass function is better fitted by a log-normal function. We estimate that brown dwarfs represent about 25% of the cluster population which nevertheless makes up less than 1.5% of the cluster mass. The early dynamical evolution of the cluster appears to have had little effect on its present mass distribution at an age of 120Myr. Comparison between the Pleiades mass function and the Galactic field mass function suggests that apparent differences may be mostly due to unresolved binary systems.
