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Luminosity function and mass segregation in M92
Marconi, G.; Buonanno, R.; Iannicola, G. +2 more
We present WFPC2-HST observations of the lower main sequence of the galactic globular cluster M92 (NGC6341), extending down to V ~= 27. Our data, which cover a region of the cluster extending from the very center out to r ~= 380 arcsec, show that the slope of the luminosity function becomes flatter going towards the center of the cluster, as expec…
A wind accretion wake in RW Hydrae?
Schmutz, W.; Nussbaumer, H.; Schild, H. +3 more
RW Hydrae is an eclipsing detached binary star system, consisting of a mass losing M-giant and a hot white dwarf on circular orbits. We analyze UV observations of RW Hydrae. Approximately at phi = 0.78, clearly unrelated to the primary eclipse, we detect in the UV light curve an event with significantly reduced UV flux. The spectral characteristic…
Comparisons of the Tycho-2 Catalogue Proper Motions with HIPPARCOS and ACT
Makarov, V. V.; Urban, S. E.; Wycoff, G. L.
The recently released Tycho-2 Catalogue is expected to supersede the currently used catalogs based on the Tycho data, specifically, the ACT Reference Catalog and the Tycho Reference Catalogue. Here the proper motions of the newly released Tycho-2 Catalogue are compared with those of the Hipparcos Catalogue and the ACT Reference Catalog. Tycho-2 is…
Hercules X-1: Empirical Models of Ultraviolet Emission Lines
Raymond, John; Bautista, Manuel; Boroson, Bram +4 more
The UV emission lines of Hercules X-1, resolved with the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph, can be divided into broad (FWHM~750 km s-1) and narrow (FWHM~150 km s-1) components. The broad lines can be unambiguously identified with emission from an accreti…
Variable Galaxies in the Hubble Deep Field
Phillips, M. M.; Gilliland, Ronald L.; Sarajedini, Vicki L.
We present results from a study to detect variable galaxies in the Hubble Deep Field North (HDF-N). The goal of this project is to investigate the number density of active galactic nuclei (AGNs) at z~=1 through the detection of variable galaxy nuclei. The advantage of the Hubble Space Telescope is its ability to do accurate photometry within small…
Mode Identification of BPM 37093 with the HST
Kepler, S. O.; Montgomery, M. H.; Winget, D. E. +3 more
Theoretical calculations indicate that the massive pulsating white dwarf BPM 37093 has a crystallized interior (Winget et al. 1997, Kanaan 1996, Montgomery 1998). Crystallization was predicted theoretically about 40 years ago (Abrisokov 1961, Kirshnitz 1960; Salpeter 1961), but in spite of its importance in astrophysics, there is no direct observa…
The Vela pulsar (PSR B0833-45) proper motion revisited with HST astrometry
Caraveo, P. A.; De Luca, A.; Mignani, R. P.
Using all the HST WFC/WFPC2 images of the field collected so far, we have performed an accurate relative astrometry analysis to re-assess the value of the Vela pulsar proper motion. Although covering a much shorter time span, our measurement clearly confirms the previous result obtained by Nasuti et al. (1997) using ground-based optical data and n…
Far-infrared-loud quasars - I. Disturbed and quiescent quasars in the PG survey
Clements, D. L.
We use host galaxy imaging studies of the PG quasar survey to compare the far-infrared (FIR) properties of quasars with disturbed and undisturbed host galaxies. By using survival analysis, we show that the quasars with disturbed host galaxies, with morphologies classified from a homogeneous data set, have a 60-µm luminosity distribution that…
Hubble Space Telescope and Very Large Array Observations of the H2O Gigamaser Galaxy TXS 2226-184
Wilson, Andrew S.; Henkel, Christian; Falcke, Heino +2 more
We present Hubble Space Telescope/Wide-Field and Planetary Camera 2 images in Hα + [N II] λλ6548, 6583 lines and continuum radiation and a VLA map at 8 GHz of the H2O gigamaser galaxy TXS 2226-184. This galaxy has the most luminous H2O maser emission known to date. Our red continuum images reveal a highly elongated galaxy wit…
Interpreting the optical data of the Hubble Deep Field South: colors, morphological number counts and photometric redshifts
Chincarini, G.; Bolzonella, M.; Saracco, P. +1 more
We present an analysis of the optical data of the Hubble Deep Field South. We derive F300WAB, F450WAB, F606WAB and F814WAB number counts for galaxies in our catalogue (Volonteri et al. 2000): the number-counts relation has an increasing slope up to the limits of the survey in all four bands. The slope is…