Search Publications
Suzaku Observations of M 82 X-1 : Detection of a Curved Hard X-Ray Spectrum
Gandhi, Poshak; Makishima, Kazuo; Miyawaki, Ryohei +5 more
A report is presented on Suzaku observations of the ultra-luminous X-ray source X-1 in the starburst galaxy M 82, made three times in 2005 October for an exposure of ∼30ks each. The XIS signals from a region of radius 3' around the nucleus defined a 2--10keV flux of 2.1 × 10-11erg s-1cm-2 attributable to point sour…
Hubble Space Telescope Images and KPNO Spectroscopy of the Binary Black Hole Candidate SDSS J153636.22+044127.0
Lauer, Tod R.; Boroson, Todd A.
We present Hubble Space Telescope WFPC2/PC images and KPNO 4 m long-slit spectroscopy of the QSO SDSS J153636.22+044127.0, which we advanced as a candidate binary supermassive black hole. The images reveal a close companion coincident with the radio source identified by Wrobel & Laor. It appears to be consistent with a Mg ~ -21.4 el…
A sporadic layer in the Venus lower ionosphere of meteoric origin
Pätzold, M.; Christou, A. A.; Bird, M. K. +4 more
The Venus Express Radio Science (VeRa) experiment aboard Venus Express has detected, by means of radio occultation, distinct, low-lying layers of electron density below the base (115 km altitude) of the ionosphere of Venus. A plausible origin of these lowest layers is ionization by the influx of meteoroids into the atmosphere. The layers appeared …
Mode width fitting with a simple Bayesian approach. Application to CoRoT targets HD 181420 and HD 49933
Appourchaux, T.; Boumier, P.; Gaulme, P.
Aims: We investigate the asteroseismology of two solar-like targets as observed with the CoRoT satellite, with particular attention paid to the mode fitting. HD 181420 and HD 49933 are typical CoRoT solar-like targets (156 and 60-day runs). The low signal-to-noise ratio (SNR) of about 3{-}10 prevents us from unambiguously identifying the individua…
Discovery of lake-effect clouds on Titan
Brown, R. H.; Baines, K. H.; Clark, R. N. +5 more
Images from instruments on Cassini as well as from telescopes on the ground reveal the presence of sporadic small-scale cloud activity in the cold late-winter north polar region of Saturn's large moon Titan. These clouds lie underneath the previously discovered uniform polar cloud attributed to a quiescent ethane cloud at ~40 km and appear confine…
The young stellar population at the center of NGC 205
Bellazzini, M.; Saviane, I.; Monaco, L. +5 more
Context: NGC 205 is a peculiar dwarf elliptical galaxy hosting in its center a population of young blue stars. Their origin is still matter of debate, the central fresh star formation activity possibly being related to dynamical interactions between NGC 205 and M 31.
Aims: The star formation history in the central 30´´ (~120 pc) around the NGC…
Metastable methane clathrate particles as a source of methane to the martian atmosphere
Chassefière, Eric
The observations of methane made by the PFS instrument onboard Mars Express exhibit a definite correlation between methane mixing ratio, water vapor mixing ratio, and cloud optical depth. The recent data obtained from ground-based telescopes seem to confirm the correlation between methane and water vapor. In order to explain this correlation, we s…
Long-term photometry and periods for 261 nearby pulsating M giants
Kjeldsen, H.; Kiss, L. L.; Bedding, T. R. +3 more
We present the results of a 5.5-yr CCD photometric campaign that monitored 261 bright, southern, semiregular variables (SRVs) with relatively precise Hipparcos parallaxes. The data are supplemented with independent photoelectric observations of 34 of the brightest stars, including 11 that were not part of the CCD survey, and a previously unpublish…
Effect of Polarimetric Noise on the Estimation of Twist and Magnetic Energy of Force-Free Fields
Gosain, Sanjay; Joshi, Jayant; Tiwari, Sanjiv Kumar +1 more
The force-free parameter α, also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global value of α for a whole active region gives the degree of twist per unit axial length. We investigate the effect of polarimetric noise on the calculation of global α value…
Variations in the dip properties of the low-mass X-ray binary XB 1254-690 observed with XMM-Newton and INTEGRAL
Díaz Trigo, M.; Parmar, A. N.; Boirin, L. +3 more
We have analysed data from five XMM-Newton observations of XB 1254-690, one of them simultaneous with INTEGRAL, to investigate the mechanism responsible for the highly variable dip durations and depths seen from this low-mass X-ray binary. Deep dips were present during two observations, shallow dips during one and no dips were detected during the …