Next: NGC 660 Up: The Group of Nearby Previous: The Group of Nearby . NGC 253 is a nearby edge-on galaxy and the brightest member of the Sculptor group. ... The strong and extended radio emission makes it especially suitable for H I absorption measurements (see e.g., Combes, Gottesman & Weliachew 1977; Dickey, Brinks & Puche 1992; Koribalski, Whiteoak & Houghton 1995). ... Column (1): Galaxy name. ... Next: NGC 660 Up: The Group of Nearby Previous: The Group of Nearby Baerbel Koribalski . ...

We present optical, ultraviolet (UV) and extreme ultraviolet (EUV) results for a new active late-type dwarf star discovered by the Extreme Ultraviolet Explorer (EUVE). A large flare with an energy in excess of 1E35 erg and duration of ~1.1 days was detected in the EUVE Lex/B band (60--200AA). ... The `quiescent' EUV emission of the source is similar to the most active flare stars with the `quiescent' optical spectrum showing strong H alpha, Ca II H Mg II h emission and Li I 6707.8A absorption. ...

High-resolution mid-infrared spectra are presented for 155 nuclear and extranuclear regions from the Spitzer Infrared Nearby Galaxies Survey (SINGS). ... Conversely, the radiation hardness for galaxy nuclei powered by accretion around a massive black hole is independent of metal abundance. ... However, similar to [Ne III] 15.56 ЮМm/[Ne II] 12.81 ЮМm, these mid-infrared line ratios lose their AGN/star-formation diagnostic powers for very low metallicity star-forming systems with hard radiation fields. ...

... Flux density at 1 GHz (/Jy): 8 . ... Optical: Filaments and diffuse emission. ... Distance: Mean optical velocity indicates 6.7 kpc, H I absorption indicates 2.3 kpc. ... NRAO 300-ft at 2.7 GHz (5': S=5.3?0.6 Jy). ADS . van den Bergh 1978, ApJS, 38, 119. Optical. ... 1975, AuJPA, 37, 75. Molonglo at 408 MHz (3': S=11.7 Jy). ... Arecibo S 430 MHz =20?10 Jy, S 318 MHz =20?3.6 Jy. ... Einstein and optical observations. ... VLA at 327 MHz (59") and 1.49 GHz (52"), plus X-rays. ...

... 55 Cancri: Familiar Planet Discovered . ... Is our Solar System unique? The discovery of a Jupiter-like planet in a Jupiter-like orbit around nearby Sun-like star 55 Cancri, announced yesterday, gives a new indication that planetary systems similar to our Solar System likely exist elsewhere. ... Part of the Sun disappeared behind the Moon earlier this week. Previously, the waning Moon was best visible from all places on Earth during the early morning hours because it trailed the Sun. ...

... astro-ph/0003002 We cross-identified the ROSAT Bright Source Catalog (RBSC) and the NRAO VLA Sky Survey (NVSS) to construct the RBSC-NVSS sample of the brightest X-ray sources (~0.1 counts s^{-1} ~= 10^{-12} ergs cm^-2s^-1 in the 0.1--2.4 keV band) that are also radio sources (S ~= 2.5 mJy at 1.4 GHz) in the 7.8 sr of extragalactic sky with |b| > 15deg and DEC > -40deg. ... We used the more accurate radio positions to make reliable X-ray/radio/optical identifications down to the POSS plate limits. ...

... The presence of solid­state emission bands is compared to other indicators of circumstellar material, such as Hff emission, optical variability and sub­mm continuum fluxes. ... However, a strong dependence on spectral type of the central star seems to be present: stars with spectral type earlier than B9 show either amorphous silicate in absorption or infrared spectra dominated by PAH emission, whereas more than 70% of the stars of later spectral type show silicate emission. ...

... Some optical observations of auroral forms have indicated anomalous enhancement of emission within a very limited altitude range of about 2 km (Oguti, 1975; Stenbaek-Nielsen and Hallinan, 1979; Stenbaek-Nielsen, 1980a, b), and have been called as enhanced aurora. ... Res. ... Oguti, T., Two-tiered auroral band, J. Atmos. ... Res., 85 , 4299, 1980b. Stenbaek-Nielsen, H. C., and T. N. Hallinan, Pulsating auroras: Evidence for noncollisional thermalization of precipitating electrons, J. Geophys. ...

... 2004 September 1 . An Inner Neptune for 55 Cancri . ... The discovery of a Neptune -mass planet in an sub-Mercury orbit around nearby Sun -like star 55 Cancri , announced yesterday along with the discovery of other similar systems, gives a new indication that planetary systems as complex as our own Solar System likely exist elsewhere. ... The above drawing depicts what this planet might look like, assuming a mass similar to Neptune , but a composition similar to Earth. ... About APOD | ...