scholarly journals Detections of inflowing gas from narrow absorption lines at parsec scales

2021 ◽  
Author(s):  
Z. F. Chen ◽  
M. Gu ◽  
Z. He ◽  
D. Bu ◽  
F. Guo ◽  
...  
Keyword(s):  
Absorption Lines

scholarly journals Influence of Gravitational Lensing on Estimates of Ω in Neutral Hydrogen

1996 ◽  
Vol 173 ◽  
pp. 97-98
Author(s):  
Matthias Bartelmann ◽  
Abraham Loeb
Keyword(s):  
Observational Data ◽  
Gravitational Lensing ◽  
Column Density ◽  
Spiral Galaxies ◽  
Neutral Hydrogen ◽  
Absorption Lines ◽  
Gravitational Lenses ◽  
High Column

A wealth of observational data supports the commonly held view that damped Lyman-α (Lyα) absorption in QSO spectra is associated with neutral-hydrogen (HI) disks in spiral galaxies. Most of the HI probed by QSO absorption lines is traced by damped Lyα lines because of their high column densities, N > 1020 cm–2. The spiral galaxies hosting the HI disks can act as gravitational lenses on the QSOs. If the HI column density increases towards the center of the disks, as suggested by observations of local galaxies, the magnification bias preferentially selects for high column-density systems. The estimates of HI in damped Lyα systems can then systematically be distorted by gravitational lensing.

scholarly journals The stellar velocity field in M 51

1970 ◽  
Vol 38 ◽  
pp. 79-82
Author(s):  
S. M. Simkin
Keyword(s):  
Velocity Field ◽  
Large Deviations ◽  
Rotation Curve ◽  
Radial Velocities ◽  
Absorption Lines ◽  
Image Tube ◽  
Stellar Velocity

Radial velocities have been measured from the absorption lines on two image tube spectra of M 51. These velocities show large deviations from the ‘smoothed’ rotation curve for that object. The measurements seem to indicate that both the stars and the gas move in the same way.

1.55-μm-band practical frequency-stabilized semiconductor laser using C 2 H 2 or HCN absorption lines

1993 ◽  
Author(s):  
Satoshi Yoshitake ◽  
Koji Akiyama ◽  
Miyako Iritani ◽  
Hidekazu Murayama
Keyword(s):  
Semiconductor Laser ◽  
Absorption Lines

On the Origin of Intrinsic Narrow Absorption Lines inz ≲ 1 QSOs

2001 ◽  
Vol 549 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Rajib Ganguly ◽  
Nicholas A. Bond ◽  
Jane C. Charlton ◽  
Michael Eracleous ◽  
W. N. Brandt ◽  
...  
Keyword(s):  
Absorption Lines

OPTICAL ABSORPTION SPECTRA OF ARSENIC AND PHOSPHORUS IN SILICON

1962 ◽  
Vol 40 (10) ◽  
pp. 1480-1489 ◽  
Author(s):  
J. W. Bichard ◽  
J. C. Giles
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Excited States ◽  
Ground State ◽  
Absorption Lines ◽  
Full Width ◽  
Optical Absorption Spectra ◽  
Phosphorus Impurity ◽  
Line Widths ◽  
Phosphorus In Silicon

The optical absorption spectra of arsenic and phosphorus donor impurities in silicon have been studied under conditions of improved resolution. Absorption lines due to transitions from the impurity ground state to the excited states 2p0, 2p±, 3p0, 3p±, 4p0, 4 p±, and 5p0, and 5p± have been observed at 4.2° K. The relative intensities of some of these absorption lines are compared with existing experimental and theoretical estimates. The contribution of instrumental broadening to the observed line widths is assessed and natural line widths are estimated. The estimates indicate values for the natural line widths which are much less than those previously reported. For phosphorus impurity, the natural line widths are estimated to be less than 0.08 × 10−3 electron volts full width at half-maximum. The possibility of concentration broadening is discussed in connection with the arsenic data.

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