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Further Evidence for Chemical Fractionation from Ultraviolet Observations of Carbon Monoxide
Andersson, B. -G.; van Dishoeck, Ewine F.; Federman, S. R. +4 more
Ultraviolet absorption from interstellar 12CO and 13CO was detected toward ρ Oph A and χ Oph. The measurements were obtained at medium resolution with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. Column density ratios, N(12CO)/N(13CO), of 125+/-23 and 117+/-35 were derived for …
Follow-Up Hubble Space Telescope/Space Telescope Imaging Spectroscopy of Three Candidate Tidal Disruption Events
Komossa, S.; Grupe, D.; Halpern, J. P. +2 more
Large-amplitude, high-luminosity, soft X-ray flares were detected by the ROSAT All-Sky Survey in several galaxies with no evidence for Seyfert activity in their ground-based optical spectra. These flares had the properties predicted for a tidal disruption event by a central supermassive black hole: soft X-ray spectrum, timescale of months, and lar…
Star cluster formation and disruption time-scales - II. Evolution of the star cluster system in the fossil starburst of M82
de Grijs, Richard; Bastian, Nate; Lamers, Henny J. G. L. M.
We obtain new age and mass estimates for the star clusters in the fossil starburst region B of M82, based on improved fitting methods. Our new age estimates confirm the peak in the age histogram attributed to the last tidal encounter with M81; we find a peak formation epoch at slightly older ages than previously published, log(tpeak yr<…
The Nearby Neutron Star RX J0720.4-3125 from Radio to X-Rays
Frail, D. A.; Kulkarni, S. R.; van Kerkwijk, M. H. +3 more
We present radio, optical, ultraviolet, and X-ray observations of the isolated, thermally emitting neutron star RX J0720.4-3125 using the Parkes radio telescope, the Very Large Array, the Hubble Space Telescope, and the Chandra X-Ray Observatory. From these data we show that the optical/UV spectrum of RX J0720.4-3125 is not well fitted by a Raylei…
Buried Alive in the Coronal Graveyard
Ayres, Thomas R.; Harper, Graham M.; Brown, Alexander
We have used the High Resolution Camera (HRC-I) of the Chandra X-Ray Observatory to search for coronal (T~106 K) emission from the archetype ``noncoronal'' red giants Arcturus (α Bootis=HD 124897, K1 III) and Aldebaran (α Tauri=HD 29139, K5 III). Our program follows up previous detections of ultraviolet coronal proxies such as C IV λ154…
Cloning Dropouts: Implications for Galaxy Evolution at High Redshift
Broadhurst, Tom; Bouwens, Rychard; Illingworth, Garth
The evolution of high-redshift galaxies in the two Hubble Deep Fields, HDF-N and HDF-S, is investigated using a cloning technique that replicates z~2-3 U dropouts to higher redshifts, allowing a comparison with the observed B and V dropouts at higher redshifts (z~4-5). We treat each galaxy selected for replication as a set of pixels that are k-cor…
The Evolution of the Galaxy Luminosity Function in the Rest-Frame Blue Band up to z=3.5
Cimatti, A.; Daddi, E.; Fontana, A. +14 more
We present an estimate of the cosmological evolution of the field galaxy luminosity function (LF) in the rest-frame 4400 Å B band up to redshift z=3.5. To this purpose, we use a composite sample of 1541 I-selected galaxies selected down to IAB=27.2 and 138 galaxies selected down to KAB=25 from ground-based and HST multicolor …
Space Velocities of Southern Globular Clusters. IV. First Results for Inner Galaxy Clusters
Girard, Terrence M.; van Altena, William F.; López, Carlos E. +1 more
We have measured the absolute proper motions of four low-latitude, inner Galaxy globular clusters. These clusters are NGC 6266 (M62), NGC 6304, NGC 6316, and NGC 6723. The proper motions are on the Hipparcos system, since no background extragalactic objects are found in these high-extinction regions. The proper-motion uncertainties range between 0…
Distances to nearby galaxies around IC 342
Dolphin, A. E.; Grebel, E. K.; Sharina, M. E. +1 more
We present an analysis of Hubble Space Telescope/WFPC2 images of six nearby galaxies in the projected vicinity of IC 342: Cas dSph, KK 35, UGCA 86, Cam A, NGC 1560, and Cam B. We derive distances to five of them from the luminosity of the tip of the red giant branch stars with a typical accuracy of ~ 10%. The galaxy distances are 0.79 Mpc (Cas dSp…
Monte Carlo simulations and generation of the SPI response
von Kienlin, A.; Shrader, C. R.; Schanne, S. +13 more
In this paper we discuss the methods developed for the production of the INTEGRAL/SPI instrument response. The response files were produced using a suite of Monte Carlo simulation software developed at NASA/GSFC based on the GEANT-3 package available from CERN. The production of the INTEGRAL/SPI instrument response also required the development of…