Search Publications
Detection of a γ-ray burst of very long duration and very high energy
Cline, T.; Hurley, K.; Fishman, G. J. +24 more
ALTHOUGH γ-ray bursts (GRBs) have been known for more than 20 years, their origin remains mysterious1. Suggestions have ranged from nearby colliding comets2 to merging neutron stars at cosmological distances3. The lack of any counterpart at wavelengths other than X-rays and γ-rays has posed a major problem in ident…
Distance to the Virgo cluster galaxy M100 from Hubble Space Telescope observations of Cepheids
Illingworth, Garth D.; Kennicutt, Robert C.; Madore, Barry F. +11 more
Accurate distances to galaxies are critical for determining the present expansion rate of the Universe or Hubble constant (H0). An important step in resolving the current uncertainty in H0 is the measurement of the distance to the Virgo cluster of galaxies. New observations using the Hubble Space Telescope yield a distance of…
Detection of intergalactic ionized helium absorption in a high-redshift quasar
Boksenberg, A.; Deharveng, J. M.; Jakobsen, P. +3 more
Observations obtained with the recently refurbished Hubble Space Telescope reveal strong absorption arising from singly ionized helium along the line of sight to a high-redshift quasar. The strength of the absorption suggests that it may arise in a diffuse ionized intergalactic medium. The detection also confirms that substantial amounts of helium…
Evidence for a quasar in the radio galaxy Cygnus A from observation of broad-line emission
Antonucci, Robert; Hurt, Todd; Kinney, Anne
ACTIVE galaxies are thought to be powered by the accretion of surrounding dust and gas onto central black holes. The unified model1-3 of active galaxies predicts that narrow-line radio galaxies (NLRGs), which are very luminous at radio wavelengths and have narrow optical emission lines, would appear as quasars—which have broad emission …
Dust formation in Nova Cassiopeiae 1993 seen by ultraviolet absorption
Sonneborn, G.; Hauschildt, P. H.; Shore, S. N. +2 more
The clouds of gas in interstellar space also contain grains of dust, whose properties and origins have been the focus of debate for decades. Some dust formation has been assumed to take place in novae explosions1-5, as was first implied by the observation of a steep decrease in the amount of light emitted by the nova1,2 DQ He…