Search Publications
Hubble Space Telescope Observations of Novae in M49
Jordán, Andrés; Côté, Patrick; Ferrarese, Laura
A search for novae in M49 (NGC 4472) has been undertaken with the Hubble Space Telescope. A 55 day observing campaign in F555W (19 epochs) and F814W (five epochs) has led to the discovery of nine novae. We find that M49 may be underabundant in slow, faint novae relative to the Milky Way and M31. Instead, the decline rates of the M49 novae are rema…
Erosion Model for the Sungrazing Comets Observed with the Solar and Heliospheric Observatory
Sekanina, Zdenek
The objectives of this study are to model and interpret quantitatively the brightness variations of 27 Solar and Heliospheric Observatory (SOHO) sungrazers. The light curves, published by Uzzo et al. and by Biesecker et al., are shown to provide information on a proposed erosion process, which consists of continuous, progressive bulk fragmentation…
Tether-cutting Energetics of a Solar Quiet-Region Prominence Eruption
Moore, Ronald L.; Sterling, Alphonse C.
We study the morphology and energetics of a slowly evolving quiet-region solar prominence eruption occurring on 1999 February 8-9 in the solar north polar crown region, using soft X-ray data from the soft X-ray telescope (SXT) on Yohkoh and Fe XV EUV 284 Å data from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO). …
Evidence for Grain Growth in the Protostellar Disks of Orion
Bally, John; Throop, Henry; Shuping, R. Y. +1 more
We present a Brα (λ=4.05 µm) image of the largest silhouette proplyd in Orion (114-426) using the facility near-IR spectrometer NIRSPEC at the Keck Observatory. This is the longest wavelength observation of a silhouette disk to date. The diameter of the disk at 4 µm is only marginally smaller than that observed in the optical with the …
A Multiwavelength Approach to the Star Formation Rate Estimation in Galaxies at Intermediate Redshifts
Elbaz, D.; Koo, D. C.; Willmer, C. N. A. +4 more
We use a sample of seven starburst galaxies at intermediate redshifts (z~0.4 and 0.8) with observations ranging from the observed ultraviolet to 1.4 GHz, to compare the star formation rate (SFR) estimators that are used in the different wavelength regimes. We find that extinction-corrected Hα underestimates the SFR, and the degree of this underest…
The Variability of the Solar Coronal Helium Abundance: Polar Coronal Holes Compared to the Quiet Sun
Laming, J. Martin; Feldman, Uri
We report on measurements of the abundance ratio He/H in solar polar coronal holes and neighboring quiet coronal regions, using the SUMER spectrometer on board SOHO. In coronal holes we find He abundances smaller than or equal to the value found in the fast solar wind, 5% by number relative to H, suggesting that the flow speed of He up into the wi…
Protoplanetary Disk Mass Distribution in Young Binaries
Jensen, Eric L. N.; Akeson, Rachel L.
We present millimeter-wave continuum images of four wide (separations 210-800 AU), young stellar binary systems in the Taurus-Auriga star-forming region. For all four sources, the resolution of our observations is sufficient to determine the millimeter emission from each of the components. In all four systems, the primary star's disk has stronger …
Reconstructing a Cepheid Light Curve with Fourier Techniques. I. The Fourier Expansion and Interrelations
Tanvir, Nial R.; Ngeow, Chow-Choong; Kanbur, Shashi M. +2 more
Fourier decomposition is a well-established technique used in the study of stellar pulsation. However, the quality of reconstructed light curves using this method is reduced when the observed data have uneven phase coverage. We use simulated annealing techniques together with Fourier decomposition to improve the quality of the Fourier decompositio…
XMM-Newton Observation of the 5.25 Millisecond Transient Pulsar XTE J1807-294 in Outburst
Campana, S.; Belloni, T.; Israel, G. L. +2 more
We report on the results obtained for the millisecond transient X-ray pulsar XTE J1807-294 in a 40 minute orbital period system, based on an XMM-Newton target-of-opportunity observation carried out during 2003 March. The source was found at a luminosity level of about 2×1036 ergs s-1 in the 0.5-10 keV range (assuming a distan…
The Optical Counterpart of the Isolated Neutron Star RX J1605.3+3249
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaplan, D. L.
We have detected the optical counterpart to the nearby isolated neutron star RX J1605.3+3249 using observations from the Space Telescope Imaging Spectrometer aboard the Hubble Space Telescope. The counterpart, with m50CCD=26.84+/-0.07 mag and very blue colors, lies close to the ROSAT HRI error circle and within the Chandra error circle.…