Portal:Radiation astronomy/Topic/3
Absorptions
[edit | edit source]"[P]referential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon".[1]
"For quenched galaxies, the Hα absorption trough is deep and can be traced through the nucleus and along the major axis. It extends to a radius at or beyond 2 Rd [where Rd is the galaxy disk scale length] in all but three cases. This makes it possible to determine a velocity width from the optical spectrum as is done for emission line flux, with appropriate corrections between stellar and gas velocities (see discussion in Paper I, also Neistein, Maoz, Rix, & Tonry, 1999). In the few cases where a velocity width can also be measured from the H I data, it is found to be in good agreement with that taken from the Hα absorption line flux."[2]
References
[edit | edit source]- ↑ Craig F. Bohren. Atmospheric Optics. http://homepages.wmich.edu/%7Ekorista/atmospheric_optics.pdf.
- ↑ Nicole P. Vogt and Martha P. Haynes, Riccardo Giovanelli, and Terry Herter (June 2004). "M/L, Hα Rotation Curves, and HI Gas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters". The Astronomical Journal 127 (6): 3325-37. doi:10.1086/420703. http://iopscience.iop.org/1538-3881/127/6/3325. Retrieved 2013-12-20.