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Modeling the Hubble Space Telescope Ultraviolet and Optical Spectrum of Spot 1 on the Circumstellar Ring of SN 1987A
Filippenko, Alexei V.; Zhekov, Svetozar A.; Pun, Chun S. J. +18 more
We report and interpret Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) long-slit observations of the optical and ultraviolet (1150-10270 Å) emission line spectra of the rapidly brightening spot 1 on the equatorial ring of SN 1987A between 1997 September and 1999 October (days 3869-4606 after outburst). The emission is cau…
Off-limb EUV line profiles and the search for wave activity in the low corona
Harrison, R. A.; Hood, A. W.; Pike, C. D.
Two extreme-ultraviolet (EUV) observations are used to examine the off-limb characteristics of emission line widths of the million K Mg X 625 Å line. To obtain sufficient statistical accuracy, the observations were made over long periods of time and a pixel summing technique is used. The observations are made above the western limb, for quiet coro…
Boron Abundances in B-Type Stars: A Test of Rotational Depletion during Main-Sequence Evolution
Lennon, D. J.; Keenan, F. P.; Lambert, David L. +4 more
Boron abundances have been derived for seven main-sequence B-type stars from Hubble Space Telescope STIS spectra around the B III λ2066 line. In two stars, boron appears to be undepleted with respect to the presumed initial abundance. In one star, boron is detectable but is clearly depleted. In the other four stars, boron is undetectable, implying…
The Eagle's EGGs: Fertile or sterile?
Andersen, M.; McCaughrean, M. J.
We present a deep, high spatial resolution (0.35 arcsec FWHM), near-infrared (1-2.5 mu m) imaging survey of the Eagle Nebula, M 16, made with the VLT, centred on the famous elephant trunks. We compare these data with the existing HST optical images to search for evidence of ongoing or recent star formation in the trunks, and in particular in the 7…
Wind variability of B supergiants. IV. A survey of IUE time-series data of 11 B0 to B3 stars
Massa, D.; Prinja, R. K.; Fullerton, A. W.
We present the most suitable data sets available in the International Ultraviolet Explorer (IUE) archive for the study of time-dependent stellar winds in early B supergiants. The UV line profile variability in 11 B0 to B3 stars is analysed, compared and discussed, based on 16 separate data sets comprising over 600 homogeneously reduced high-resolu…
Determination of the Distance to M33 Based on Single-Epoch I-Band Hubble Space Telescope Observations of Cepheids
Sarajedini, Ata; Lee, Myung Gyoon; Gieren, Wolfgang +2 more
We have determined the distance to M33 using single-epoch I-band observations of Cepheids based on Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 (WFPC2) images of five fields in M33. Combining the HST I-band photometry and the periods determined from the ground-based observations (DIRECT) for 21 Cepheids with logP>0.8 in the sample…
Detection of a Super-Star Cluster as the Ionizing Source in the Low-Luminosity Active Galactic Nucleus NGC 4303
Leitherer, Claus; Colina, Luis; Mas-Hesse, J. Miguel +1 more
Hubble Space Telescope (HST) ultraviolet Space Telescope Imaging Spectrograph (STIS) imaging and spectroscopy of the low-luminosity active galactic nucleus (LLAGN) NGC 4303 have identified the previously detected UV-bright nucleus of this galaxy as a compact, massive, and luminous stellar cluster. The cluster with a size (FWHM) of 3.1 pc and an ul…
Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton
Parmar, A. N.; Boirin, L.; Oosterbroek, T. +1 more
We report the discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X1624-490 during an XMM-Newton observation in 2001 February. The features are identified with the Kalpha absorption lines of Fe XXV and Fe XXVI and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV and equivalent widths (EWs) of -7.5 +1.7…
HST observations of the protoplanetary nebula OH 231.8+4.2: The structure of the jets and shocks
Sahai, R.; Sánchez Contreras, C.; Alcolea, J. +1 more
We present high-resolution images obtained with the WFPC2, on board the HST, of the protoplanetary nebula (PPN) OH 231.8+4.2. Hα and NII line emission and scattered light in the continuum at 6750 and 7910 Å were observed. We also discuss NIR NICMOS images from the HST archive. The images show with high accuracy the shape and excitation state of th…
ISO ammonia line absorption reveals a layer of hot gas veiling Sgr B2
Prusti, T.; Ceccarelli, C.; Caux, E. +7 more
We report the first results of the unbiased spectral high resolution survey obtained towards Sgr B2 with the Long Wavelength Spectrometer on board ISO. The survey detected more than one hundreds lines from several molecules. Ammonia is the molecule with the largest number (21) of detected lines in the survey. We detected NH3 transitions…