8 research outputs found
Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third Edition - Comments and Statistics
The Catalogue, available at the Centre de Donn\'ees Stellaires de Strasbourg,
consists of 13573 records concerning the results obtained from different
methods for 7778 stars, reported in the literature. The following data are
listed for each star: identifications, apparent magnitude, spectral type,
apparent diameter in arcsec, absolute radius in solar units, method of
determination, reference, remarks. Comments and statistics obtained from CADARS
are given.Comment: A&A, in pres
Gas and dust in the inner disk of the Herbig Ae star MWC 758
In this Letter we investigate the origin of the near-infrared emission of the
Herbig Ae star MWC 758 on sub-astronomical unit (AU) scales using spectrally
dispersed low resolution (R=35) AMBER/VLTI interferometric observations both in
the H (m) and K (m) bands. We find that the K band
visibilities and closure phases are consistent with the presence of a dusty
disk inner rim located at the dust evaporation distance (0.4 AU) while the bulk
of the H band emission arises within 0.1 AU from the central star. Comparing
the observational results with theoretical model predictions, we suggest that
the H band emission is dominated by an hot gaseous accretion disk.Comment: Accepted for publication in A&
Near-infrared interferometric observation of the Herbig Ae star HD144432 with VLTI/AMBER
We study the sub-AU-scale circumstellar environment of the Herbig Ae star
HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the
structure of its inner dust disk. The interferometric observations were carried
out with the AMBER instrument in the H and K band. We interpret the measured H-
and K-band visibilities, the near- and mid-infrared visibilities from the
literature, and the SED of HD144432 by using geometric ring models and
ring-shaped temperature-gradient disk models with power-law temperature
distributions. We derived a K-band ring-fit radius of 0.17 \pm 0.01 AU and an
H-band radius of 0.18 \pm 0.01 AU (for a distance of 145 pc). This measured
K-band radius of \sim0.17 AU lies in the range between the dust sublimation
radius of \sim0.13 AU (predicted for a dust sublimation temperature of 1500 K
and gray dust) and the prediction of models including backwarming (\sim0.27
AU). We found that an additional extended halo component is required in both
the geometric and temperature-gradient modeling. In the best temperature-
gradient model, the disk consists of two components. The inner part of the disk
is a thin ring with an inner radius of \sim0.21 AU, a temperature of \sim1600
K, and a ring thickness \sim0.02 AU. The outer part extends from \sim1 AU to
\sim10 AU with an inner temperature of \sim400 K. We find that the disk is
nearly face-on with an inclination angle of < 28 degree. Our
temperature-gradient modeling suggests that the NIR excess is dominated by
emission from a narrow, bright rim located at the dust sublimation radius,
while an extended halo component contributes \sim6% to the total flux at 2
{\mu}m. The MIR model emission has a two-component structure with \sim20% flux
from the inner ring and the rest from the outer part. This two-component
structure suggests a disk gap, which is possibly caused by the shadow of a
puffed-up inner rim.Comment: 7 pages, 5 figures, accepted by A&
Synthetic and Observed Photometric Indices for Globular Clusters in the Galaxy and M31
Buzzoni's (1989) grid of synthetic spectral energy distributions,
representative of old stellar populations, was used to derive colours in
different photometric systems, and to compare the theoretical predictions with
the observational data referring to about globular clusters in the Galaxy
and to objects of the globular cluster system of M31. Synthetic and
observed indices display an overall agreement in the composite planes of
two-colour diagrams, thus in agreement with the standard evolutionary scenario
leading, for globular clusters, to old stellar populations consistent with an
age of Gyr and a Salpeter initial mass function (IMF). The two main
parameters modulating the cluster colour distributions are, as known,
metallicity and horizontal branch morphology, while IMF slope and mass loss
rate from stars in the red-giant branch and asymptotic-giant branch
evolutionary stages produce only minor, although not negligible, effects on the
integrated colours. The M31 and Galactic cluster populations are found to be
substantially similar, at least as far as the spectral energy distribution
characteristics in the spectral range are concerned.Comment: (23 pages, uuencoded and compressed PostScript, available also by
anonymous ftp at bach.mi.astro.it in /priv/users/covino as paper.ps.Z).
Accepted for publication in Astronomy and Astrophysics. FFSP-940