Search Publications
Missions
Journals
Publication Years
Probing the brown dwarf population of the Chamaeleon I star forming region
Neuhäuser, R.; Comerón, F.; Kaas, A. A.
We present observations of a sample of 13 very low mass stars and brown dwarfs in the central region of the Chamaeleon I star forming cloud. The observations include slitless spectroscopy around Hα to identify new members, low resolution long-slit visible and near-infrared spectroscopy, deep ROSAT PSPC X-ray observations, and ISOCAM mid-infrared o…
ISO-SWS observations of OMC-1: H_2 and fine structure lines
Bertoldi, F.; Drapatz, S.; Rosenthal, D.
Using the Short-Wavelength-Spectrometer on the Infrared Space Observatory (ISO), we obtained near- and mid-infrared spectra toward the brightest H_2 emission peak of the Orion OMC-1 outflow. A wealth of emission and absorption features were detected, dominated by 56 H_2 ro-vibrational and pure rotational lines reaching from H_2 0-0 S(1) to 0-0 S(2…
Tests of the Accelerating Universe with Near-Infrared Observations of a High-Redshift Type IA Supernova
Spyromilio, J.; Filippenko, Alexei V.; Leibundgut, B. +25 more
We have measured the rest-frame B-, V-, and I-band light curves of a high-redshift type Ia supernova (SN Ia), SN 1999Q (z=0.46), using the Hubble Space Telescope (HST) and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, EB-I, a sensitive indicator of interstellar or intergalactic dust, …
Non-parametric star formation histories for four dwarf spheroidal galaxies of the Local Group
Gilmore, Gerard; Valls-Gabaud, David; Hernandez, X.
We use recent Hubble Space Telescope colour-magnitude diagrams of the resolved stellar populations of a sample of local dSph galaxies (Carina, Leo I, Leo II and Ursa Minor) to infer the star formation histories of these systems, SFR(t). Applying a new variational calculus maximum likelihood method, which includes a full Bayesian analysis and allow…
X-Ray Sources in the Hubble Deep Field Detected by Chandra
Hornschemeier, A. E.; Brandt, W. N.; Sargent, W. L. W. +11 more
We present first results from an X-ray study of the Hubble Deep Field North (HDF-N) and its environs obtained using 166 ks of data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. This is the deepest X-ray observation ever reported, and in the HDF-N itself we detect six X-ray sources down to a 0.5-8…
High-Resolution Imaging of Molecular Gas and Dust in the Antennae (NGC 4038/39): Super Giant Molecular Complexes
Wilson, Christine D.; Madden, Suzanne C.; Charmandaris, Vassilis +1 more
We present new aperture synthesis CO maps of the Antennae (NGC 4038/39) obtained with the Caltech Millimeter Array. These sensitive images show molecular emission associated with the two nuclei and a partial ring of star formation to the west of NGC 4038, as well as revealing the large extent of the extranuclear region of star formation (the ``ove…
Implications of Solar Wind Composition for Cometary X-Rays
Schwadron, N. A.; Cravens, T. E.
Solar wind composition provides a strong source of variability for cometary X-rays. Using recently constrained composition observations from the Solar Wind Ion Composition Spectrometer on the Ulysses spacecraft (SWICS/Ulysses) and information on ion-neutral charge-transfer collisions, we model cometary X-ray emission and its variability. Fast and …
A spectroscopic study of coronal dimming associated with a coronal mass ejection
Harrison, R. A.; Lyons, M.
Extreme ultraviolet spectroscopic observations of one coronal mass ejection event are used to examine the onset phase of the eruption. We find significant dimming of million K plasmas in the low corona under the ascending CME, the activation of an adjacent prominence and 2 million K `hot spots' which may be associated with the CME footpoints. In p…
The C-C-C bending modes of PAHs: a new emission plateau from 15 to 20 µm
Waters, L. B. F. M.; Hony, S.; Tielens, A. G. G. M. +9 more
We have obtained 2.5-45 mu m spectra of a sample of compact H ii regions, YSOs and evolved stars in order to study the origin and evolution of interstellar Polycyclic Aromatic Hydrocarbon molecules (PAHs). Besides the well-known, strong PAH bands at 3.3, 6.2, 7.7, 8.6, and 11.2 mu m, these spectra reveal for the first time, a ubiquitous emission p…
STIS Observations of HE II Gunn-Peterson Absorption toward Q0302-003
Tripp, Todd M.; Jenkins, Edward B.; Hubeny, Ivan +5 more
The ultraviolet spectrum (1145-1720 Å) of the distant quasar Q0302-003 (z=3.286) was observed at 1.8 Å resolution with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. A total integration time of 23,280 s was obtained. The spectrum clearly delineates the Gunn-Peterson He II absorption trough, produced by He II Lyα along …