Search Publications
Hubble Space Telescope Observations of Ultraviolet Oscillations in WZ Sagittae During the Decline from Outburst
Szkody, Paula; Sion, Edward M.; Godon, Patrick +4 more
We present a time series analysis of Hubble Space Telescope observations of WZ Sge obtained in 2001 September, October, November, and December as WZ Sge declined from its 2001 July superoutburst. Previous analysis of these data showed the temperature of the white dwarf decreased from ~29,000 to ~18,000 K. In this study we binned the spectra over w…
`Hyper-parameters' approach to joint estimation: applications to Cepheid-calibrated distances and X-ray clusters
Lahav, Ofer; Ettori, Stefano; Erdogdu, Pirin
We use a generalized procedure for the combined likelihood analysis of different cosmological probes, the `hyper-parameters' method, that allows freedom in the relative weights of the raw measurements. We perform a joint analysis of the Cepheid-calibrated data from the Hubble Space Telescope Key Project and the baryon mass fraction in clusters to …
Hydrogen atom lifetimes in the three-dimensional heliosphere over the solar cycle
Pryor, Wayne R.; Ajello, Joseph M.; Tobiska, W. Kent +2 more
The three-dimensional (3-D) structure of the heliosphere is investigated using in situ and remote sensing measurements. The 3-D structure of both neutral interplanetary gas and solar wind ions are affected by the solar latitude variation of the solar radiation fields (solar wind and solar EUV). Neutral hydrogen atom lifetimes against charge-exchan…
Chromospheric activity and unique solution of SZ Psc
Kang, Young Woon; Lee, Woo-Baik; Kim, Ho-il +1 more
We have confirmed that the MgII h and k emission lines of SZ Psc are mainly enhanced by the K subgiant component of the system, using the radial velocities reduced from the emission lines. The intensity variation of the emission line is correlated with the orbital phase of SZ Psc. The shape of light curves of SZ Psc were changing every season. The…
Hubble Space Telescope observations of sulfur ions in the Io plasma torus: New constraints on the plasma distribution
Schneider, Nicholas M.; Hendrix, Amanda R.; Herbert, Floyd +1 more
During the Io plasma torus crossings by the Galileo spacecraft in late 1999 and early 2000 we observed the dawn ansa of the torus using the Hubble Space Telescope (HST). Here we analyze 74 FUV HST/Space Telescope Imaging Spectrograph observations (1150 ≤ λ ≤ 1720 Å) of the dawn ansa of the Io plasma torus made during Galileo's C23, I24, and I27 to…
Inversion of the intensity-magnetic field relationship in solar active regions
Fludra, A.; Ireland, J.
We discuss the relationship between the EUV spectral line intensities and the photospheric magnetic flux in solar active regions. Since the histograms of the magnetic flux density in active region plages can be approximated by an exponential function, the equation describing how the observed total line intensity integrated over an active region ar…
Star-Forming Knots in the UV-Bright Interacting Galaxies NGC 3395 and NGC 3396
Hancock, Mark; Nelson, Charles H.; Weistrop, Donna +1 more
We have obtained ultraviolet and visible wavelength images for the central regions of the interacting galaxies NGC 3395 and NGC 3396, using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The images show many isolated sources of ultraviolet emission produced by young star-forming regions (knots). The FWHM of most of the kno…
Early-Type Stars: Most Favorable Targets for Astrometrically Detectable Planets in the Habitable Zone
Fischer, Debra A.; Gould, Andrew; Ford, Eric B.
Early-type stars appear to be a difficult place to look for planets astrometrically. First, they are relatively heavy, and for fixed planetary mass the astrometric signal falls inversely as the stellar mass. Second, they are relatively rare (and so tend to be more distant), and for fixed orbital separation the astrometric signal falls inversely as…
[C II] emission and star formation in late-type galaxies. II. A model
Völk, H. J.; Pierini, D.; Leech, K. J.
We study the relationship between gas cooling via the [C II] (lambda = 158 µm) line emission and dust cooling via the far-IR continuum emission on the global scale of a galaxy in normal (i.e. non-AGN dominated and non-starburst) late-type systems. It is known that the luminosity ratio of total gas and dust cooling, LC II/ LFI…
Sharp boundary between the inner magnetosphere and active outer plasma sheet
Sauvaud, J. -A.; Balogh, A.; Zong, Q. -G. +6 more
We report observations of a sharp spatial boundary between the outer plasma sheet and the inner magnetosphere. It was successively crossed by the Cluster spacecraft in their pearl-on-string configuration near the perigee (~4 Re) at midnight during a substorm expansion phase. Being mapped presumably to 8-10 Re in the equatorial tail, this boundary …