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Detection of an X-Ray Pulsar Wind Nebula and Tail in SNR N157B
Gotthelf, E. V.; Wang, Q. D.; Chu, Y. -H. +1 more
We report Chandra X-ray observations of the supernova remnant N157B in the Large Magellanic Cloud, which are presented together with an archival Hubble Space Telescope optical image and a radio continuum map for comparison. This remnant contains the recently discovered 16 ms X-ray pulsar PSR J0537-6910, the most rapidly rotating young pulsar known…
An Imaging and Spectroscopic Study of the zabs=3.38639 Damped Lyα System in Q0201+1120: Clues to Star Formation at High Redshift
Pettini, Max; Ellison, Sara L.; Shapley, Alice E. +1 more
We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the zabs=3.38639 damped Lyα system in the zem=3.61 quasar Q0201+1120. We find that the damped Lyα systems (DLA) is part of a concentration of matter that includes at least four galaxies (pr…
Mass-losing Semiregular Variable Stars in Baade's Windows
Genzel, R.; Alard, C.; Blommaert, J. A. D. L. +38 more
By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 µm) and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galac…
The Discovery of Circumstellar Arcs around Two Bipolar Proto-planetary Nebulae
Kwok, Sun; Hrivnak, Bruce J.; Su, Kate Y. L.
Circumstellar arcs have been discovered using the Hubble Space Telescope in two proto-planetary nebulae (PPNs), IRAS 16594-4656, and IRAS 20028+3910. This raises to five the number of PPNs in which such arcs have been detected and suggests that they are not rare and may even be common features. All five of these PPNs display a bipolar morphology, …
Oxygen Abundances in Metal-poor Stars (-2.2<[Fe/H]<-1.2) from Infrared OH Lines
Meléndez, Jorge; Barbuy, Beatriz; Spite, François
Infrared OH lines at 1.55-1.56 µm in the H band were obtained with the Phoenix high-resolution spectrograph at the 2.1 m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample stars have been carried out, deriving stellar parameters based on two methods: (a) spectroscopic paramete…
Eruption and acceleration of flare-associated coronal mass ejection loops in the low corona
Plunkett, S. P.; Thompson, B. J.; Gurman, J. B. +1 more
Observations made by the EUV imaging telescope (EIT) and the Large-Angle Spectrometric Coronagraph (LASCO) on board the Solar Heliospheric Observatory (SOHO) have been used to characterize the eruption and acceleration of flare-associated coronal mass ejections (CMEs) in the low corona. For three well-observed limb events we tracked CME loops back…
The Nuclear Cusp Slopes of Dwarf Elliptical Galaxies
Ferguson, Henry C.; Mack, Jennifer; Stiavelli, Massimo +3 more
We derive the light profiles for a sample of 25 dwarf elliptical galaxies observed by us with Hubble Space Telescope's Wide Field and Planetary Camera 2 in F555W and F814W. These profiles are fitted with Nuker, R1/4, exponential, and Sersic laws and are also used to derive the nuclear cusp slopes γ. We discuss the correlation of nuclear…
Intrinsic and Reprocessed Optical Emission from the Companion to PSR J2051-0827
Kulkarni, S. R.; van Kerkwijk, M. H.; Stappers, B. W. +1 more
Hubble Space Telescope observations of the companion to the eclipsing millisecond pulsar PSR J2051-0827 have revealed its ``dark'' side. The R magnitude at minimum is ~26, while the difference between the side heated by the impinging pulsar radiation and the unirradiated side is ~3.3 mag. For the first time, these data show that there is an asymme…
Cepheid Calibration of the Peak Brightness of Type IA Supernovae. X. SN 1991T in NGC 4527
Panagia, N.; Saha, A.; Labhardt, Lukas +5 more
Repeated imaging observations have been made of NGC 4527 with the Hubble Space Telescope between 1999 April and June, over an interval of 69 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F814W band. The galaxy hosted the Type Ia supernova SN 1991T, which showed relatively unusual behavior by having both an abn…
IRAS 09425-6040: A carbon star surrounded by highly crystalline silicate dust
Loup, C.; Yamamura, I.; Molster, F. J. +4 more
We present infrared spectroscopy and millimeter photometry and spectroscopy of the peculiar carbon star IRAS 09425-6040. The 2-15 mu m spectrum, as well as the CO millimeter line observations are typical for a (J-type) carbon star with moderate mass-loss rate. The 15-45 mu m spectrum is dominated by strong emission bands from Mg-rich and Fe-poor c…