Search Publications
Herschel observations of extended atomic gas in the core of the Perseus cluster
Baum, Stefi A.; O'Dea, Christopher P.; Donahue, Megan +11 more
We present Herschel observations of the core of the Perseus cluster of galaxies. Especially intriguing is the network of filaments that surround the brightest cluster galaxy, NGC 1275, previously imaged extensively in Hα and CO. In this work, we report detections of far-infrared (FIR) lines, in particular, [C II] 158, [O I] 63, [N II] 122, [O IB] …
The Cluster of Blue Stars Surrounding the M31 Nuclear Black Hole
Green, Richard F.; Kormendy, John; Lauer, Tod R. +2 more
We obtained U 330- and B-band images of the M31 nucleus using the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The spatial resolution in the U 330 band, 0farcs03 FWHM, or 0.1 pc at M31, is sufficient to resolve the outskirts of the compact cluster (P3) of UV-bright stars…
AKARI Observations of Brown Dwarfs. III. CO, CO2, and CH4 Fundamental Bands and Physical Parameters
Yamamura, I.; Sorahana, S.
We investigate variations in the strengths of three molecular bands, CH4 at 3.3 µm, CO at 4.6 µm, and CO2 at 4.2 µm, in 16 brown dwarf spectra obtained by AKARI. Spectral features are examined along the sequence of source classes from L1 to T8. We find that the CH4 3.3 µm band is present in …
The Panchromatic Hubble Andromeda Treasury. I. Bright UV Stars in the Bulge of M31
Bell, Eric F.; Skillman, Evan D.; Williams, Benjamin F. +20 more
As part of the Panchromatic Hubble Andromeda Treasury multi-cycle program, we observed a 12' × 6farcm5 area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of ~4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify …
Study of LINER sources with broad Hα emission. Spectral energy distribution and multiwavelength correlations
Grosso, N.; Porquet, D.; Reeves, J. N. +2 more
Context. The geometry and physical properties of the accretion mode, and the radiative processes occurring in AGN-powered low ionization nuclear emission-line regions (LINERs) remain a riddle. Both a standard thin accretion disk and an inner-hot radiatively-inefficient accretion flow (RIAF) have been invoked. Models depending on only a jet have al…
Radar properties of comets: Parametric dielectric modeling of Comet 67P/Churyumov-Gerasimenko
Kofman, Wlodek; Heggy, Essam; Palmer, Elizabeth M. +3 more
In 2014, the European Space Agency’s Rosetta mission is scheduled to rendezvous with Comet 67P/Churyumov-Gerasimenko (Comet 67P). Rosetta’s CONSERT experiment aims to explore the cometary nucleus’ geophysical properties using radar tomography. The expected scientific return and inversion algorithms are mainly dependent on our understanding of the …
Electron pitch-angle diffusion in radiation belts: The effects of whistler wave oblique propagation
Krasnoselskikh, V.; Breuillard, H.; Agapitov, O. +2 more
We calculated the electron pitch-angle diffusion coefficients in the outer radiation belt for L-shell ∼4.5 taking into account the effects of oblique whistler wave propagation. The dependence of the distribution of the angle θ between the whistler wave vector and the background magnetic field on magnetic latitude is modeled after statistical resul…
Quantitative spectroscopy of Galactic BA-type supergiants. I. Atmospheric parameters
Przybilla, N.; Firnstein, M.
Context. BA-type supergiants show a high potential as versatile indicators for modern astronomy. This paper constitutes the first in a series that aims at a systematic spectroscopic study of Galactic BA-type supergiants. Various problems will be addressed, including in particular observational constraints on the evolution of massive stars and a de…
Solar cycle variations of the Cluster spacecraft potential and its use for electron density estimations
Fazakerley, A. N.; Trotignon, J. -G.; Haaland, S. +5 more
A sunlit conductive spacecraft, immersed in tenuous plasma, will attain a positive potential relative to the ambient plasma. This potential is primarily governed by solar irradiation, which causes escape of photoelectrons from the surface of the spacecraft, and the electrons in the ambient plasma providing the return current. In this paper we comb…
Neutron star masses from hydrodynamical effects in obscured supergiant high mass X-ray binaries
Walter, R.; Manousakis, A.; Blondin, J. M.
Context. A population of obscured supergiant high mass X-ray binaries has been discovered by INTEGRAL. X-ray wind tomography of IGR J17252-3616 inferred a slow wind velocity to account for the enhanced obscuration.
Aims: The main goal of this study is to understand under which conditions high obscuration could occur.
Methods: We have use…