Search Publications
A spectral analysis of the periodicity hypothesis in cratering records
Yabushita, Shin
Analysis is made of cratering records, whereby not only the crater ages, but also the sizes can be naturally taken into account. The method adopted is the periodogram analysis first discussed by Lomb. From the crater data based on Grieve's compilation, a period can be derived when a statistical weight of a crater is taken proportional to the size …
Unveiling SU Aurigae in the Near-Infrared: New High Spatial Resolution Results Using Adaptive Optics
Ge, Jian; Chakraborty, Abhijit
We present new results on the circumstellar nebulosity around SU Aurigae, a T Tauri star of about 2 Msolar and 5 Myr old at 152 pc in the J, H, and K bands using high-resolution adaptive optics imaging (0.30") with the Penn State Near-IR Imager and Spectrograph at the 100 inch (2.5 m) Mount Wilson telescope. A comparison with Hubble Spa…
ISOPHOT 95 µm observations in the Lockman Hole. The catalogue and an assessment of the source counts
Rodighiero, G.; Franceschini, A.
We report results from a new analysis of a deep 95 µm imaging survey with ISOPHOT on board the Infrared Space Observatory, over a ∼1 deg2 area within the Lockman Hole, which extends the statistics of our previous study (Rodighiero et al. \cite{Rodighiero03}). Within the survey area we detect sixty-four sources with S/N>3 (rough…
Far Ultraviolet Spectroscopic Explorer Spectroscopy of Absorption and Emission Lines from the Narrow-Line Seyfert 1 Galaxy NGC 4051
Brandt, W. N.; Kaspi, Shai; Elvis, Martin +2 more
We present three Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the narrow-line Seyfert 1 galaxy NGC 4051. The most prominent features in the far-ultraviolet (FUV) spectrum are the O VI emission and absorption lines and the H I Lyman series absorption lines, which are detected up to the Lyman edge. We also identify weak emission fro…
Two New X-Ray/Optical/Radio Supernova Remnants in M31
Gelfand, Joseph D.; Williams, Benjamin F.; Kong, Albert K. H. +3 more
We compare a deep (37 ks) Chandra ACIS-S image of the M31 bulge to Local Group Survey narrowband optical data and Very Large Array (VLA) radio data of the same region. Our precisely registered images reveal two new optical shells with X-ray counterparts. These shells have sizes, [SII]/Hα flux ratios, and X-ray spectral properties typical of supern…
Warm-hot Intergalactic Medium Emission and the Cluster Soft Excess: A Model Comparison
Bonamente, M.; Mittaz, J.; Lieu, R. +1 more
The confirmation of the cluster soft excess (CSE) by XMM-Newton has rekindled interest as to its origin. The recent detections of CSE emission at large cluster radii together with reports of O VII line emission associated with the CSE has led many authors to conjecture that the CSE is, in fact, a signature of the warm-hot intergalactic medium (WHI…
Flow in streamer boundaries, and streamer stability
Suess, S. T.; Nerney, S.
Streamers can extend to many solar radii but the closed field regions, or helmets, reach no higher than 2-4 solar radii. The brightness boundary defining streamers is therefore, a boundary between different flow regimes rather than between static plasma and expanding solar wind. It is reasonable to assume that, this boundary divides fast coronal h…
Cosmic Helium Production
Flynn, Chris
K-dwarfs are very long lived, slowly evolving stars, so that their present day helium Y and metal content (metallicity Z) is essentially the same as when they were born. K-dwarfs thus contain a fossil record of the amount of helium and metals which has been produced in successive stellar generations over the lifetime of the Galaxy. We here estimat…
Proper Motion Objects in the Hubble Deep Field
Winget, D. E.; von Hippel, Ted; Mendez, R. A. +1 more
Using the deepest and finest resolution images of the universe acquired with the Hubble Space Telescope and a similar image taken 7 yr later for the Great Observatories Origins Deep Survey, we have derived proper motions for the point sources in the Hubble Deep Field-North. Two faint blue objects, HDF 2234 and HDF 3072, are found to display signif…
Far-Ultraviolet Spectroscopy of Star-forming Regions in Nearby Galaxies: Stellar Populations and Abundance Indicators
Keel, William C.; Holberg, Jay B.; Treuthardt, Patrick M.
We present Far Ultraviolet Spectroscopic Explorer spectroscopy and supporting data for star-forming regions in nearby galaxies, to examine their massive-star content and explore the use of abundance and population indicators in this spectral range for high-redshift galaxies. New far-ultraviolet spectra are shown for four bright H II regions in M33…