Search Publications
Astrophysics in 2002
Aschwanden, Markus J.; Trimble, Virginia
This has been the Year of the Baryon. Some low temperature ones were seen at high redshift, some high temperature ones were seen at low redshift, and some cooling ones were (probably) reheated. Astronomers saw the back of the Sun (which is also made of baryons), a possible solution to the problem of ejection of material by Type II supernovae (in w…
Structure and mass distribution of spiral galaxies at intermediate redshifts
Tamm, A.; Tenjes, P.
Using the HST archive WFPC2 observations and rotation curves measured by Vogt et al. (\cite{vogt1}), we constructed self-consistent light and mass distribution models for three disk galaxies at redshifts z=0.15, 0.90 and 0.99. The models consist of three components: the bulge, the disk and the dark matter. The light distribution of the galaxies in…
The stellar environment of SMC N81
Schaerer, D.; Heydari-Malayeri, M.; Charmandaris, V. +4 more
We present near infrared JHK imaging of the Small Magellanic Cloud compact H II region N81 using the ISAAC camera at the ESO Very Large Telescope (Antu). Our analysis of the stellar environment of this young massive star region reveals the presence of three new stellar populations in the surrounding field which are mainly composed of low mass star…
Nonthermal Mass Motions within the High-Temperature Plasmas above a Complex Solar Active Region
Curdt, W.; Landi, E.; Feldman, U.
We report on mass motions in high-temperature plasmas at radial distances of 1.06-1.20 Rsolar corresponding to 3.3×104-1.3×105 km above the west solar limb. The observations were conducted over a 53 hr time period while a complex active region moved across the west solar limb. We found that the nonthermal mass moti…
Extension of the ICRF for selected areas down to the 16th magnitude - II
Ducourant, C.; Le Campion, J. -F.; Teixeira, R. +3 more
In this paper we provide a major upgrade of the work presented in \citet{cam}, aiming at the extension of the ICRF at optical wavelengths in regions of special astronomical interest, using observations from the Bordeaux and Valinhos meridian circles. Along with the new fields, the main differences, when compared to the first release, are: a much l…
XMM-Newton observations of an absorbed z= 0.67 QSO: no dusty torus?
Georgakakis, A.; Georgantopoulos, I.; Griffiths, R. E. +4 more
We present XMM-Newton observations of AX J0341.4-4453, a mildly reddened AV < 7 quasi-stellar object (QSO) at a redshift of z= 0.672. The XMM-Newton spectrum shows a large obscuring column NH~ 1023 cm-2 corresponding to AV~ 70, in agreement with previous results based on the lower limit of …
How directions and helicity of erupted solar magnetic fields define geoeffectiveness of coronal mass ejections
Wang, Haimin; Yurchyshyn, Vasyl; Abramenko, Valentyna
In this study we report on the relationship between the projected speed of CMEs, measured at 20R from SOHO/LASCO images, and the hourly averaged magnitude of the southwardly directed magnetic field, B z, at the leading edge of interplanetary ejecta, as measured by the ACE magnetometer. We found that those CMEs that originate at the cent…
A search for X-ray variability in the open cluster NGC 2516
Ramsay, Gavin; Harra, Louise; Kay, Hilary
We present the results of a search for X-ray variability in the Galactic open cluster NGC 2516. This cluster has been observed on eight occasions using XMM-Newton, making it an excellent target for such a study. We find four sources that show significant variability, implying the detection of one significantly variable source every 25 ks. All sour…
Predictions for the Counts of Faint, High-Redshift Galaxies in the Mid-Infrared
Spergel, David N.; Turner, Edwin L.; Haiman, Zoltán
Deep mid-infrared (MIR) observations could reveal a population of faint, high-redshift (z>3), dusty starburst galaxies that are the progenitors of present-day spheroids or bulges and are beyond the reach of current instruments. We utilize a semianalytic galaxy formation scheme to find a range of models for the MIR galaxy counts, down to a flux …
A study of velocity fields in the transition region of ɛ Eri (K2 V)
Jordan, C.; Sim, S. A.
Analyses of the widths and shifts of optically thin emission lines in the ultraviolet spectrum of the active dwarf ɛ Eri (K2 V) are presented. The spectra were obtained using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer. The linewidths are used to find the non-thermal energy …