Search Publications
The Mass of the MACHO-LMC-5 Lens Star
Gould, Andrew; Bennett, David P.; Alves, David R.
We combine the available astrometric and photometric data for the 1993 microlensing event MACHO-LMC-5 to measure the mass of the lens, M=0.097+/-0.016Msolar. This is the most precise direct mass measurement of a single star other than the Sun. In principle, the measurement error could be reduced as low as 10% by improving the trigonomet…
Internal Color Properties of Resolved Spheroids in the Deep Hubble Space Telescope Advanced Camera for Surveys Field of UGC 10214
Ford, H. C.; Infante, L.; Zheng, W. +31 more
We study the internal color properties of a morphologically selected sample of spheroidal galaxies taken from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Early Release Observation program of UGC 10214 (``the Tadpole''). By taking advantage of the unprecedented high resolution of the ACS in this very deep data set, we are abl…
A tale of two very different comets: ISO and MSX measurements of dust emission from 126P/IRAS (1996) and 2P/Encke (1997)
A'Hearn, M. F.; Kostiuk, T.; Grün, E. +7 more
We present the characteristics of the dust comae of two comets, 126P/IRAS, a member of the Halley family (a near-isotropic comet), and 2P/Encke, an ecliptic comet. We have primarily used mid- and far-infrared data obtained by the ISOPHOT instrument aboard the Infrared Space Observatory (ISO) in 1996 and 1997, and mid-infrared data obtained by the …
AFS dynamic evolution during the emergence of an active region
Romano, P.; Spadaro, D.; Contarino, L. +2 more
Using data acquired during an observational campaign carried out at the THEMIS telescope in IPM mode, coordinated with other ground- and space-based instruments (IOACT, TRACE, EIT/SOHO, MDI/SOHO), we have analyzed the first evolutionary phases of a recurrent active region (NOAA 10050), in order to study the morphology and dynamics of its magnetic …
X-ray flares from the ultra-luminous X-ray source in NGC 5408
Read, A. M.; Motch, C.; Soria, R. +1 more
We have studied an ultra-luminous X-ray source (ULX) in the dwarf galaxy NGC 5408 with a series of XMM-Newton observations, between 2001 July and 2003 January. We find that its X-ray spectrum is best fitted with a power law of photon index Γ ≈ 2.6-2.9 and a thermal component with blackbody temperature kTbb ≈ 0.12-0.14 keV. These spectra…
XMM-Newton and Chandra observations of three X-ray-faint early-type galaxies
O'Sullivan, E.; Ponman, T. J.
We present XMM-Newton observations of three X-ray-underluminous elliptical galaxies, NGC 3585, 4494 and 5322. All three galaxies have relatively large optical luminosities (logLB= 10.35-10.67 Lsolar) but have X-ray luminosities consistent with emission from discrete sources only. In conjunction with a Chandra observation of N…
An XMM-Newton observation of the massive, relaxed galaxy cluster ClJ1226.9+3332 at z= 0.89
Maughan, B. J.; Ebeling, H.; Jones, L. R. +1 more
A detailed X-ray analysis of an XMM-Newton observation of the high-redshift (z= 0.89) galaxy cluster ClJ1226.9+3332 is presented. After careful consideration of background subtraction issues, the X-ray temperature is found to be 11.5+1.1-0.9 keV, the highest X-ray temperature of any cluster at z > 0.6. The temperature is c…
Walén and slow-mode shock analyses in the near-Earth magnetotail in connection with a substorm onset on 27 August 2001
Balogh, A.; RèMe, H.; Vaivads, A. +6 more
We have examined Cluster spacecraft 1 (C1) magnetic field and particle observations from 27 August 2001 when the Cluster spacecraft separation was less than 0.27 RE and the spacecraft were located near the equatorial plane of the postmidnight magnetotail at xGSM ∼ -19 RE and yGSM ∼ -2.1 RE. A …
HD 108: The mystery deepens with XMM-Newton observations
Nazé, Y.; Rauw, G.; Vreux, J. -M. +1 more
In 2001, using a large spectroscopic dataset from an extensive monitoring campaign, we discovered that the peculiar Of star HD 108 displayed extreme line variations. This strange behaviour could be attributed to a variety of models, and an investigation of the high energy properties of HD 108 was needed to test the predictions from these models. O…
The Ages of Dwarf Elliptical Galaxies
Schombert, James; Rakos, Karl
We present narrowband photometry of 91 dwarf elliptical galaxies in the Coma and Fornax Clusters taken with the Strömgren (uvby) filter system. Dividing the sample by dwarf morphology into nucleated (dEN) and nonnucleated (dE) dwarfs reveals two distinct populations of early-type systems based on integrated colors. The class of dEN galaxies are re…