Search Publications
Modelling Short-Term Spectral Irradiance Variations
Solanki, S. K.; Unruh, Y. C.; Fligge, M.
On time-scales of the solar rotation most of the solar irradiance variations are caused by the changing distribution of solar surface magnetic features. We model these short-term irradiance variations using calculations of sunspot and facular contrasts as a function of wavelength and limb angle on the Sun. The position of active regions on the sol…
Structural Characteristics of Faint Galaxies Serendipitously Discovered with the Hubble Space Telescope WFPC2
Impey, C. D.; Bothun, G. D.; O'Neil, Karen
Utilizing the F814W and F300W filters, Hubble Space Telescope Wide Field Planetary Camera-2 (WFPC2) images were taken of four low surface brightness galaxies in the direction of the Virgo Cluster--V7L3, V2L8, V1L4, and Malin 1. The high resolution of the WFPC2 combined with the extremely diffuse nature of the four galaxies makes them essentially t…
IRAS galaxies in the Perseus cluster
Meusinger, H.; Brunzendorf, J.; Krieg, R.
We cross-correlate the optical catalogue of galaxies in the field of the Perseus cluster (Abell 426) with IRAS PSC sources. The optical catalogue comprises data on 660 galaxies brighter than B25 ~ 19.5 (Brunzendorf & Meusinger 1999). A sample of 19 IRAS galaxies is found. According to their redshifts, 17 galaxies are likely members …
Far infrared observations of the southern Galactic star forming complex around IRAS 09002-4732
Ghosh, S. K.; Mookerjea, B.; Tandon, S. N. +2 more
The Galactic star forming region in the southern sky, associated with IRAS 09002-4732 has been mapped simultaneously in two far infrared bands (lambda eff = 148 & 209 mu m), with ~ 1 arcmin angular resolution. Fifteen sources, including IRAS 08583-4719, 08589-4714, 09002-4732 and 09014-4736 have been detected, some of which are well…
First Detection of Submillimeter [C I] Emission in the Small Magellanic Cloud
Jackson, James M.; Bolatto, Alberto D.; Zhang, Xiaolei +1 more
We report the first detection of [C I] (3P1-->3P0) emission at 609 µm in a region of the Small Magellanic Cloud (N27). Environments poor in heavy elements and dust such as the SMC are thought to be dominated by photodissociation regions (PDRs). This is the lowest metallicity source where submill…
The Ulysses Supplement to the Granat/WATCH Catalog of Cosmic Gamma-Ray Bursts
Cline, T.; Hurley, K.; Sunyaev, R. +7 more
We present third Interplanetary Network (IPN) localization data for 56 gamma-ray bursts in the Granat/WATCH catalog that occurred between 1990 November and 1994 September. These localizations are obtained by triangulation using various combinations of spacecraft and instruments in the IPN, which consisted of Ulysses, BATSE, Pioneer Venus Orbiter, …
Direct measurement of the supernova rate in starburst galaxies
Bregman, J. D.; Temi, P.; Rank, D.
Supernovae play a key role in the dynamics, structure, and chemical evolution of galaxies. The massive stars that end their lives as supernovae live for short enough times that many are still associated with dusty star formation regions when they explode, making them difficult to observe at visible wavelengths. In active star forming regions (gala…
Internal velocity dispersion in the Hyades as a test for Tycho-2 proper motions
Makarov, V. V.; Odenkirchen, M.; Urban, S.
The Hyades stars have highly coherent motions in space which reflect in the convergence of their astrometric proper motions in or about a common convergent point. The internal dispersion of the Hyades velocities is as low as about 0.3 km s-1. This is comparable with the expected uncertainty of the Tycho-2 proper motion at the distance o…
ISO far-infrared observations of rich galaxy clusters. II. Sérsic 159-03
Nørgaard-Nielsen, H. U.; Pedersen, K.; Hansen, L. +3 more
In a series of papers we investigate far-infrared emission from rich galaxy clusters. Maps have been obtained by ISO at 60 µm, 100 µm, 135 µm, and 200 µm using the PHT-C camera. Ground based imaging and spectroscopy were also acquired. Here we present the results for the cooling flow cluster Sérsic 159-03. An infrared sourc…
The Pattern Speed of the Nuclear Disk of M31 Using a Variant of the Tremaine-Weinberg Method
Sambhus, Niranjan; Sridhar, S.
The twin peaks in the nucleus of M31 have been interpreted by Tremaine as a thick, eccentric disk of stars orbiting a massive dark object; the required alignment of the apoapsides of the stellar orbits could be maintained by self-gravity, and the whole structure might be a discrete, nonlinear eigenmode. The pattern speed of this mode could, in pri…