Search Publications
HST observations of nuclear stellar disks
Jaffe, W.; Krajnović, D.
We present observations of four nearby early-type galaxies with previously known nuclear stellar disks using two instruments on-board the Hubble Space Telescope. We observed NGC 4128, NGC 4612, and NGC 5308 with the Wide Field Planetary Camera 2, and the same three galaxies, plus NGC 4570, with the Space Telescope Imaging Spectrograph. We have det…
Photometric estimates of stellar masses in high-redshift galaxies
Berta, S.; Fritz, J.; Franceschini, A. +2 more
We present a new tool for the photometric estimate of stellar masses in distant galaxies. The observed source spectral energy distributions are fitted by combining sets of various simple stellar populations, with different normalizations and different amounts of dust extinction, for a given (Salpeter) IMF. This treatment gives us the best flexibil…
XMM-Newton Observations of the Extremely Low Accretion Rate Polars SDSS J155331.12+551614.5 and SDSS J132411.57+032050.5
Anderson, Scott F.; Brinkmann, J.; Szkody, Paula +6 more
XMM-Newton observations of the polar SDSS J155331.12+551614.5 reveal that all the X-ray flux emerges at energies less than 2 keV. The best fit to the spectrum is with a thermal plasma with kT=0.8 keV plus a 20-90 eV black body, yielding a thermal X-ray luminosity of (8.0-9.5)×1028 ergs s-1. The low temperature and X-ray lumin…
Twisted accretion curtains in the intermediate polar FO Aquarii
Cropper, Mark; Hellier, Coel; Ramsay, Gavin +1 more
We report on a ~37-ks XMM-Newton observation of the intermediate polar FO Aquarii, presenting X-ray and ultraviolet data from the EPIC and OM cameras. We find that the system has changed from its previously reported state of disc-overflow accretion to one of purely disc-fed accretion. We detect the previously reported `notch' feature in the X-ray …
New properties of energy-dispersed ions in the plasma sheet boundary layer observed by Cluster
Lundin, R.; Sauvaud, J. -A.; Escoubet, C. P. +18 more
Using multipoint measurements from the Cluster ion spectrometry instruments and the research with adaptive particle imaging detectors, we identified new properties of multiple energy-dispersed ion structures in the plasma sheet boundary layer (PSBL). On 14 February 2001 at about 4.5 RE midnight local time, the PSBL was highly structured…
Observations of the Pulsating White Dwarf G 185-32
Mazeh, T.; Hansen, C. J.; Kepler, S. O. +32 more
We observed the pulsating hydrogen atmosphere white dwarf G 185-32 with the Whole Earth Telescope in 1992. We report on a weighted Fourier transform of the data detecting 18 periodicities in its light curve. Using the Hubble Space Telescope Faint Object Spectrograph time resolved spectroscopy, and the wavelength dependence of the relative amplitud…
Transient ion beamlet injections into spatially separated PSBL flux tubes observed by Cluster-CIS
Lundin, R.; Dandouras, I.; Klecker, B. +8 more
Ion measurements from Cluster-CIS were used to characterize and interpret the signatures of PSBL energy-dispersed ions and their fine structure. On 14 February 2001, several ion injections were encountered by SC 1 and SC 3, separated by ~530 km, during an outbound orbit at 4.5 RE. Both satellites recorded the same ion structures. The en…
Cluster observations of complex 3D magnetic structures at the magnetopause
Fedorov, A.; Budnik, E.; Balogh, A. +7 more
On June 30, 2001, around 0530 UT, Cluster was moving along the magnetopause with spacecraft on both sides of the discontinuity. The configuration was `quasi-ideal' with magnetic field and plasma flow almost aligned in the magnetosheath and nearly anti-parallel to the magnetospheric field. Cluster observed several perturbations with leading and tra…
Subgiants as probes of galactic chemical evolution
Gustafsson, B.; Edvardsson, B.; Thorén, P.
Chemical abundances for 23 candidate subgiant stars have been derived with the aim at exploring their usefulness for studies of galactic chemical evolution. High-resolution spectra from ESO CAT-CES and NOT-SOFIN covered 16 different spectral regions in the visible part of the spectrum. Some 200 different atomic and molecular spectral lines have be…
A young and complex binary star - HD 144432
de Winter, D.; van den Ancker, M. E.; Bopp, B. W. +1 more
The southern emission-line star HD 144432 has received considerable attention due to its relative brightness (V ∼ 8.17), its late spectral type (late A-type or perhaps early F) and its relative isolation from a bona-fide active star formation region. We present new imaging and spectroscopic data of this star, which in the past has been classified …