Search Publications
Element mixing in the Cassiopeia A supernova
Lagage, P. O.; Cesarsky, C. J.; Douvion, T.
Thanks to mid-infrared observations, we provide new clues to the element mixing during a supernova explosion by probing the mixing between three adjacent layers: the oxygen burning products layer (sulfur, argon,...), the silicate layer and the neon layer. The silicate and neon layers are both contaminated by sulfur and argon in a macroscopic way, …
A search for rapid oscillations in chemically peculiar A-type stars
Handler, G.; Paunzen, E.
In 1995 we initiated a Northern Hemisphere survey for rapidly oscillating Ap stars. This paper presents the results including one new roAp star (HD 122970), the confirmation of rapid oscillations of HD 99563 and apparent null results for other stars. Using Hipparcos data a statistical analysis of the absolute magnitudes and galactic distributions …
A NICMOS Search for High-Redshift Elliptical Galaxy Candidates
Stiavelli, Massimo; Treu, Tommaso
We have collected optical follow-up observations from the ground and the Hubble Space Telescope (HST) for 13.74 arcmin2 of archival images taken with the HST Near-Infrared Camera and Multiobject Spectrograph (NICMOS). We use two criteria to select E/S0 galaxy candidates at z>~1 and z>~1.5 (high-redshift elliptical candidates [HizE…
SW Ursae Majoris, CU Velorum and AH Mensae: three more accreting white dwarfs unveiled?
Gänsicke, B. T.; Koester, D.
We present IUE spectroscopy of the three cataclysmic variables SW UMa, CU Vel, and AH Men. In all three systems, a broad Lyalpha absorption profile is observed. In the two short-period dwarf novae SW UMa and CU Vel, the SWP flux is interpreted as photospheric emission from white dwarfs with effective temperatures of 16 000 K and 18 500 K, respecti…
IRAS 04296+3429: a 21 MU M source with a very strong 30 MU M emission band
Henning, Th.; Szczerba, R.; Cox, P. +2 more
We report the detection of the 30 mu m emission feature from the C-rich post-Asymptotic Giant Branch (post-AGB) star IRAS 04296+3429 based on ISO SWS observations. ISO data show that there is a clear substructure in the 30 mu m feature in the form of a plateau which extends from 26 to 27 mu m. This is confirmed by the ISO SWS data for another post…
M4-18: the planetary nebula and its WC10 central star
De Marco, Orsola; Crowther, Paul A.
We present a detailed analysis of the planetary nebula M4-18 (G146.7+07.6) and its WC10-type Wolf-Rayet (WR) central star, based on high-quality optical spectroscopy (WHT/UES, INT/IDS, WIYN/DensPak) and imaging (HST/WFPC2). From a non-LTE model atmosphere analysis of the stellar spectrum, we derive T_eff=31kK, log(Msolar/M_solaryr^-1)=-6.05, v_∞=1…
Hubble Space Telescope Faint Object Spectrograph Optical and Ultraviolet Spectroscopy of the Bow Shock HH 47A
Hartigan, Patrick; Raymond, John; Tumlinson, Jason +2 more
We present new spectra obtained with the Faint Object Spectrograph aboard the Hubble Space Telescope of the HH 47A bow shock and Mach disk that cover the entire spectral range between λλ2220 and 6810. In addition to emission lines seen previously from HH objects, we uncover over a dozen weak Fe IItransitions in the ultraviolet. The flux ratios bet…
Differences in the temporal variations of galactic cosmic ray electrons and protons: Implications from Ulysses at solar minimum
Sierks, H.; Kunow, H.; Bothmer, V. +8 more
According to standard drift dominated modulation models the intensity variations of galactic cosmic ray protons and electrons respond differently to the latitudinal extension of the heliospheric current sheet α. In an A>0 solar cycle intensities of protons should vary weakly with the latitudinal extension, whereas electrons should show a strong…
Wide-Field CCD Photometry of the Globular Cluster M30
Bolte, Michael; Hesser, James E.; Sandquist, Eric L. +2 more
We present new VI photometry for the halo globular cluster M30 (NGC 7099=C2137-174) and compute luminosity functions (LFs) in both bands for samples of about 15,000 hydrogen-burning stars from near the tip of the red giant branch (RGB) to over 4 mag below the main-sequence (MS) turnoff (TO). We confirm previously observed features of the LF that a…
Dust Formation in the Hot Massive Binary HD 192641 = WR 137 (WC7 + OB)
Moffat, Anthony F. J.; Marchenko, Sergey V.; Grosdidier, Yves
Medium band (H' and K') images of the episodic dust-forming, long-period (~13 yr) WC7 + OB binary WR 137 were obtained with the Near-Infrared Camera and Multiobject Spectrometer 2 camera of the Hubble Space Telescope during periastron passage in 1997-1998. We have resolved IR-emitting dust in the close environment of this system. The dust emission…