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Neutral hydrogen absorption observations of the central region of NGC 5929
Mundell, C. G.; Holloway, A. J.; Pedlar, A. +2 more
We present 0.15-arcsec (25-pc) resolution MERLIN observations of neutral hydrogen absorption detected towards the nuclear region of the type 2 Seyfert galaxy NGC 5929. Absorption is detected only towards the north-eastern radio component with a column density of (6.5+/-0.6)x10^21cm^-2. Based on comparison with an HST WFPC2 continuum image, we prop…
HST imaging of the globular clusters in the Fornax cluster: NGC1379
Forbes, Duncan A.; Brodie, Jean P.; Grillmair, Carl J. +3 more
We present B and I photometry for ~300 globular cluster candidates in NGC1379, an E0 galaxy in the Fornax cluster. Our data are from both Hubble Space Telescope (HST) and ground-based observations. The HST photometry (B only) is essentially complete and free of foreground/background contamination to ~2 mag fainter than the peak of the globular clu…
Emission lines of [NeIV] in the optical and ultraviolet spectra of gaseous nebulae
Feibelman, W. A.; Keenan, F. P.; Espey, B. R. +5 more
Recent R-matrix calculations of electron impact excitation rates in Ne IV are used to calculate emission line ratio-ratio diagrams involving both the ultraviolet (1602, 2422 and 2424 A) and optical (4714, 4716, 4724 and 4726 A) [Ne IV] transitions, for a range of electron temperatures (T_e=10 000-30 000 K) and electron densities (N_e=10^2-10^6.5 c…
ISO observations of molecular hydrogen in the DR21 bipolar outflow
Smith, Michael D.; Davis, Christopher J.; Eisloffel, Jochen
We demonstrate that a wide range of molecular hydrogen excitation can be observed in protostellar outflows at wavelengths in excess of 5 mum. Cold H_2 in DR21 is detected through the pure rotational transitions in the ground vibrational level (0-0). Hot H_2 is detected in pure rotational transitions within higher vibrational levels (1-1, 1-2, etc.…
The separation of the stars in the binary nucleus of the planetary nebula Abell 35
Marsh, T. R.; Lynas-Gray, A. E.; Drew, J. E. +2 more
Using the Planetary Camera on board the Hubble Space Telescope, we have measured the projected separation of the binary components in the nucleus of the planetary nebula Abell 35 to be larger than 0.08 arcsec but less than 0.14 arcsec. The system has been imaged in three filters centred at 2950, 3350 and 5785 Angstroms. The white dwarf primary sta…
A search for hidden white dwarfs in theROSATEUV survey - II. Discovery of a distant DA+F6/7V binary system in a direction of low-density neutral hydrogen
Barstow, M. A.; Holberg, J. B.; Burleigh, M. R.
The ROSAT Wide Field Camera (WFC) survey of the extreme ultraviolet (EUV) has provided us with evidence for the existence of a previously unidentified sample of hot white dwarfs in unresolved, detached binary systems. These stars are invisible at optical wavelengths due to the close proximity of their much more luminous companions (spectral type K…
Eclipsing phenomena of the symbiotic star CH Cygni
Iijima, Takashi
Eclipsing phenomena of the inner binary with a period of 756 d in the triple symbiotic system CH Cyg may have been detected in detailed spectrophotometric observations. The eclipse of the hot component by the red giant started on 1994 October 11 and finished between 1995 January 8 and 18. The ingress duration was less than one day. The radius of t…
Lyalpha absorption in the nearby Universe: the sightline to Q1821+643
Bowen, David V.; Pettini, Max; Boyle, Brian J.
We present the first results of a survey designed to understand the origin of Lyalpha-forest absorption systems at low redshift. Using the WYFFOS and HYDRA multifibre spectrographs on the William Herschel and Wisconsin Indiana Yale NOAO (WIYN) telescopes, we have identified 51 galaxies brighter than b_j:=:18.5 within 30 arcmin of the sightline of …
TRIFFID Photometry of Globular Cluster Cores - I. Photometric Techniques and Variable Stars in M15
Morris, P. W.; Shearer, A.; Butler, R. F. +6 more
The Galway/DIAS Image Sharpening Camera, TRIFFID, has been used to make observations in two colours of the centre of the post-core-collapse globular cluster M15. We present here our analysis of the photometry in B over two seasons. We have combined the complementary qualities of the HST's high astrometric precision and TRIFFID's extended coverage …
The absolute magnitudes of Cepheids and the extragalacticdistance scale
Feast, Michael
It is pointed out that a Cepheid period-luminosity relation with a zero-point from Hipparcos trigonometrical parallaxes and a consistent reddening system zero-point implies that some recent estimates of H_0 based on the Cepheid scale should be increased by ~8 per cent. This result avoids using the distance to the Large Magellanic Cloud (LMC) as an…