Search Publications
Supersonic Downflows in a Sunspot Light Bridge
Venkatakrishnan, P.; Mathew, Shibu K.; Louis, Rohan E. +1 more
We report the discovery of supersonic downflows in a sunspot light bridge using measurements taken with the spectropolarimeter onboard the Hinode satellite. The downflows occur in small patches close to regions where the vector magnetic field changes orientation rapidly, and are associated with anomalous circular polarization profiles. An inversio…
Rotation of White-light Coronal Mass Ejection Structures as Inferred from LASCO Coronagraph
Yurchyshyn, Vasyl; Abramenko, Valentyna; Tripathi, Durgesh
Understanding the connection between the magnetic configurations of a coronal mass ejection (CME) and their counterpart in the interplanetary medium is very important in terms of space weather predictions. Our previous findings indicate that the orientation of a halo CME elongation may correspond to the orientation of the underlying flux rope. Her…
Flows and Motions in Moss in the Core of a Flaring Active Region: Evidence for Steady Heating
Warren, Harry P.; Brooks, David H.
We present new measurements of the time variability of intensity, Doppler, and nonthermal velocities in moss in an active region core observed by the EUV Imaging Spectrometer on Hinode in 2007 June. The measurements are derived from spectral profiles of the Fe XII 195 Å line. Using the 2'' slit, we repeatedly scanned 150'' by 150'' in a few minute…
X-rays from the Explosion Site: 15 Years of Light Curves of SN 1993J
Chandra, Poonam; Pooley, David; Immler, Stefan +2 more
We present a comprehensive analysis of the X-ray light curves of supernova (SN) 1993J in a nearby galaxy M81. This is the only SN other than SN 1987A, which is so extensively followed in the X-ray bands. Here, we report on SN 1993J observations with Chandra in the year 2005 and 2008, and Swift observations in 2005, 2006, and 2008. We combined thes…
A Population of Weak Metal-Line Absorbers Surrounding the Milky Way
Richter, Philipp; Charlton, Jane C.; Fangano, Alessio P. M. +2 more
We report on the detection of a population of weak metal-line absorbers in the halo or nearby intergalactic environment of the Milky Way. Using high-resolution ultraviolet absorption-line spectra of bright quasars (QSO) obtained with the Space Telescope Imaging Spectrograph (STIS), along six sight lines we have observed unsaturated, narrow absorpt…
Hubble Space Telescope Optical Imaging of the Eroding Debris Disk HD 61005
Scherer, K.; Graham, James R.; Schneider, G. +7 more
We present Hubble Space Telescope optical coronagraphic polarization imaging observations of the dusty debris disk HD 61005. The scattered light intensity image and polarization structure reveal a highly inclined disk with a clear asymmetric, swept back component, suggestive of significant interaction with the ambient interstellar medium (ISM). Th…
Early-Type Galaxies in the PEARS Survey: Probing the Stellar Populations at Moderate Redshift
Hathi, Nimish P.; Koekemoer, Anton M.; Pirzkal, Nor +10 more
Using Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample—extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z > 0…
A Spitzer Study of 21 and 30 µm Emission in Several Galactic Carbon-Rich Protoplanetary Nebulae
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce J.
We have carried out mid-infrared spectroscopy of seven Galactic protoplanetary nebulae (PPNs) using the Spitzer Space Telescope. They were observed from 10 to 36 µm at relatively high spectral resolution, R ≈ 600. The sample was chosen because they all gave some evidence in the visible of a carbon-rich chemistry. All seven of the sources sho…
Suzaku Observations of Local Ultraluminous Infrared Galaxies
Sanders, D. B.; Nakagawa, Takao; Veilleux, Sylvain +7 more
We report the results from our analysis of Suzaku X-ray Imaging Spectrometer (XIS) (0.5-10 keV) and Hard X-ray Detector (HXD)/PIN (15-40 keV) observations of five well-known local ultraluminous infrared galaxies: IRAS F05189 - 2524, IRAS F08572 + 3915, Mrk 273, PKS 1345 + 12, and Arp 220. The XIS observations of F05189 - 2524 and Mrk 273 reveal st…
Hubble Space Telescope Survey of Interstellar High-velocity Si III
Shull, J. Michael; Giroux, Mark L.; Collins, Joseph A.
We describe an ultraviolet spectroscopic survey of interstellar high-velocity cloud (HVC) absorption in the strong λ1206.500 line of Si III using the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. Because the Si III line is 4-5 times stronger than O VI λ1031.926, it provides a sensitive probe of ionized gas down to column …