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E+A Galaxies with Blue Cores: Active Galaxies in Transition
Zabludoff, Ann I.; Zaritsky, Dennis; Yang, Yujin +1 more
Hubble Space Telescope (HST) ACS images reveal blue cores in four E+A, or post-starburst, galaxies. Follow-up spectroscopy shows that these cores have LINER spectra. The existence of LINERs, consistent with those in many elliptical galaxies, is yet one more piece of evidence that these postmerger, post-starburst, bulge-dominated galaxies will evol…
High-metallicity, photoionized gas in intergalactic large-scale filaments
Frye, Brenda L.; Bowen, David V.; Tripp, Todd M. +3 more
We present high-resolution ultraviolet spectra of absorption-line systems towards the low-z quasi-stellar object (QSO) HS 0624+6907 (zQSO= 0.3700). Coupled with ground-based imaging and spectroscopic galaxy redshifts, we find evidence that many of these absorbers do not arise in galaxy haloes but rather are truly intergalactic gas cloud…
Near-Infrared and Optical Limits for the Central X-Ray Point Source in the Cassiopeia A Supernova Remnant
Pavlov, G. G.; Fesen, R. A.; Sanwal, D.
We set new near-infrared and optical magnitude limits for the central X-ray point source (XPS) in the Cassiopeia A supernova remnant based on HST images. Near-infrared images of the center of Cas A taken with the NICMOS 2 camera in combination with the F110W and F160W filters (~J and H bands) have magnitude limits >=26.2 and >=24.6, respecti…
MARSIS radar sounder evidence of buried basins in the northern lowlands of Mars
Stofan, Ellen R.; Clifford, Stephen M.; Safaeinili, Ali +7 more
A hemispheric dichotomy on Mars is marked by the sharp contrast between the sparsely cratered northern lowland plains and the heavily cratered southern highlands. Mechanisms proposed to remove ancient crust or form younger lowland crust include one or more giant impacts, subcrustal transport by mantle convection, the generation of thinner crust by…
On the cross-correlation of sub-mm sources and optically selected galaxies
Mobasher, Bahram; Pope, Alexandra; Scott, Douglas +1 more
Bright submillimetre (sub-mm) galaxies are expected to arise in massive highly biased haloes, and hence exhibit strong clustering. We argue that a valuable tool for measuring these clustering properties is the cross-correlation of sub-mm galaxies with faint optically selected sources. We analyse populations of sub-mm detected and optical galaxies …
Experimental and theoretical study of hydrocarbon photochemistry applied to Titan stratosphere
Vuitton, V.; Raulin, F.; Doussin, J. -F. +2 more
None of the Titan photochemical models currently available have been able to reproduce the full set of stratospheric molecular mixing ratios inferred from observations. In order to assess how well reaction sets describe hydrocarbon chemistry, theoretical modeling predictions were compared to the results of a laboratory experiment. A CH 4
A far-infrared molecular and atomic line survey of the Orion KL region
Barlow, M. J.; Cernicharo, J.; Goicoechea, J. R. +8 more
We have carried out a high spectral resolution (λ/Δλ ~ 6800-9700) line survey towards the Orion Kleinmann-Low (KL) cluster from 44 to 188 µm. The observations were taken with the Long Wavelength Spectrometer (LWS) in Fabry-Pérot mode, on board the Infrared Space Observatory (ISO). A total of 152 lines are clearly detected and a further 34 fe…
The High-Velocity Outflow of PG 1211+143 May Not Be That Fast
Kaspi, Shai; Behar, Ehud
We analyze the X-ray spectrum of the quasar PG 1211+143 observed with the CCD and grating spectrometers on board XMM-Newton. Using an ion-by-ion fitting model, we find an outflow component of about 3000 km s-1, which includes absorption lines of K and L shell ions of the astrophysically abundant elements. We also identify and include in…
Absolute motions of globular clusters. II. HST astrometry and VLT radial velocities in NGC 6397
Anderson, J.; Milone, A. P.; Bedin, L. R. +5 more
In this paper we present a new, accurate determination of the three components of the absolute space velocity of the Galactic globular cluster NGC 6397 (l≃338°, b≃-12°). We used three HST/WFPC2 fields with multi-epoch observations to obtain astrometric measurements of objects in three different fields in this cluster. The identification of 33 back…
Nature of magnetic fluctuations in Saturn's middle magnetosphere
Russell, C. T.; Dougherty, M. K.; Leisner, J. S. +2 more
The saturnian magnetosphere contains a rich array of plasma wave and MHD wave phenomena. These waves are fed by mass loading in the region of the E ring starting with Enceladus at 3.9 Saturn radii (Rs). In this paper we examine the nature of these waves in what we term to be the middle magnetosphere from just outside the mass loading at Enceladus …