Daniel R. Altschuler

IRAS 14070+0525 : an OH gigamaser at z=0.265

OH gigamaser emission has been detected in the luminous FIR galaxy IRAS 14070+0525 at a redshiht of 0.265. The FIR luminosity of IRAS 14070+0525 is 10 12.5 L ⊙ . The OH line luminosity is 1.4 x 10 4 L ⊙ , making it the most luminous known OH emitter. The OH line emission covers a velocity range of approximately 2400 km/s. Two distinct components in the OH emission reveal a powerful outflow component and/or the interactive nature of the system

Detection of atomic hydrogen in the young planetary nebula IC 4997

On rapporte la detection de lhydrogene neutre atomique a 21 cm en direction de IC 4997. La profondeur optique de la raie est 0,13±0,02 et le gaz se distingue parfaitement de lhydrogene neutre galactique

Atomic hydrogen in planetary nebulae

The authors searched for neutral atomic hydrogen associated with 22 planetary nebulae and three evolved stars in the 21 cm line at the Arecibo Observatory. Objects whose radial velocities permitted discrimination from Galactic H I were chosen for observation. Hydrogen was detected in absorption from IC 4997. From the measurements new low limits are derived to the mass of atomic hydrogen associated with the undetected nebulae. Radio continuum observations were also made of several of the nebulae at 12.6 cm. The authors reexamine previous measurements of H I in planetary nebulae, and present the data on a consistent footing. The question of planetary nebula distances is considered at length. Finally, implications of the H I measurements for nebular evolution are discussed and it is suggested that atomic hydrogen seen in absorption was expelled from the progenitor star during the final 1000 yr prior to the onset of ionization. 68 references.