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Solar wind stream interfaces in corotating interaction regions: SWICS/Ulysses results
Wimmer-Schweingruber, Robert F.; von Steiger, Rudolf; Paerli, Raoul
Motivated by the well-known differences in charge state and even elemental composition of the slow solar wind as compared to high-speed streams, we have analyzed observations made by the Solar Wind Ion Composition Spectrometer (SWICS)/Ulysses mass spectrometer of the series of corotating interaction regions (CIRs) encountered by Ulysses in 1992/19…
HST and Infrared Images of the Circumstellar Environment of the Cool Hypergiant IRC + 10420
Smith, Nathan; Humphreys, Roberta M.; Davidson, Kris +6 more
We present HST WFPC2 and ground-based infrared images of the very evolved, luminous OH/IR star IRC+10420. The HST optical images reveal an amazingly complex environment, with one or more distant reflection shells probably ejected during the star's previous red supergiant stage plus numerous features within two arcseconds of the star including cond…
Hubble Space Telescope Observations of Two Dynamically Young Elliptical Galaxies
Whitmore, Bradley C.; Fall, S. Michael; Miller, Bryan W. +1 more
High-resolution images of the candidate dynamically young ellipticals NGC 1700 and NGC 3610 have been obtained with the WFPC2 of the Hubble Space Telescope. NGC 1700 contains approximately a dozen dust clouds arranged in a chaotic distribution near the center of the galaxy, suggestive of a merger or accretion event. NGC 3610 contains a remarkably …
Separate Lightcurves of Pluto and Charon
Buie, Marc W.; Wasserman, Lawrence H.; Tholen, David J.
We present new Hubble Space Telescope observations of the Pluto-Charon system taken with WFPC1 (PC6) between 1992 May 21 and 1993 August 18. Our observations consist of 52 images with the F555W filter and 8 images in the F439W filter. From these data we extracted individual lightcurves, phase coefficients, and colors for Pluto and Charon. These li…
A massive black hole at the centre of the quiescent galaxy M32
van der Marel, Roeland P.; Rix, Hans-Walter; de Zeeuw, P. Tim +1 more
Massive black holes are thought to reside at the centres of many galaxies1,2, where they power quasars and active galactic nuclei. But most galaxies are quiescent, indicating that any central massive black hole present will be starved of fuel and therefore detectable only through its gravitational influence on the motions of the surroun…
Stellar Populations in the Dwarf Elliptical Galaxy NGC 147
Krist, J.; Stapelfeldt, K.; Gallagher, J. S., III +16 more
Deep V and I CCD images in a central and an outer field of the Local Group dwarf elliptical galaxy NGC 147 have been obtained with the Wide Field and Planetary Camera-2 (WFPC2) on board of the Hubble Space Telescope. The color-magnitude diagram shows a number of interesting features, including a well defined red giant branch (RGB), a red horizonta…
Observations of the Hubble Deep Field with the Infrared Space Observatory - III. Source counts and P(D) analysis
Elbaz, D.; Danese, L.; Franceschini, A. +19 more
We present source counts at 6.7 and 15 µm from our maps of the Hubble Deep Field (HDF) region, reaching 38.6 muJy at 6.7 µm and 255 muJy at 15 mum. These are the first ever extragalactic number counts to be presented at 6.7 mum, and are three decades fainter than IRAS at 12 mum. Both source counts and a P(D) analysis suggest that we ha…
Stellar Populations in the Large Magellanic Cloud:Evidence for a Significant Number of Older Stars or a Steeper IMF?
Stapelfeldt, K. R.; Clarke, J. T.; Grillmair, Carl J. +14 more
We present deep photometry obtained with the HST in an outer LMC field. A well-defined main sequence is seen down to V>26. We derive a luminosity function from the data and use it to constrain the IMF and the star formation history. We derive limits on the IMF slope, alpha (with dN/dM~ M(alpha ) ), from stars on the main sequence which are fain…
Metals in the variable DA G29-38
Koester, D.; Shipman, H. L.; Provencal, J.
We report the detection of the heavy elements Ca, Mg, Fe in the atmosphere of the variable DA white dwarf G29-38. The abundance of Ca can be understood only if accretion from interstellar matter is going on currently at a high rate. This lends support also the interpretation of the observed infrared excess as due to heated circumstellar material, …
A Comparison of Deep HST Luminosity Functions of Four Globular Clusters
Piotto, Giampaolo; Cool, Adrienne M.; King, Ivan R.
From deep color-magnitude arrays made from V and I images taken with Hubble Space Telescope's WFPC2 camera we have determined luminosity functions (LFs) down to a level that corresponds to ~ 0.13 \msun, for the low-metal-abundance globular clusters M15, M30, M92, and NGC 6397. Because of the similarity of the metallicities of these clusters, diffe…