Interstellar absorption lines in the galaxy NGC 1705

1990 ◽  
Vol 351 ◽  
pp. 412 ◽  
Author(s):  
D. G. York ◽  
A. Caulet ◽  
P. Rybski ◽  
J. Gallagher ◽  
J. C. Blades ◽  
...  
Keyword(s):  
Absorption Lines ◽  
Interstellar Absorption ◽  
The Galaxy

scholarly journals 10. Radio observations of interstellar neutral hydrogen clouds

1957 ◽  
Vol 4 ◽  
pp. 66-66
Author(s):  
R. S. Lawrence
Keyword(s):  
Angular Resolution ◽  
Neutral Hydrogen ◽  
Optical Component ◽  
Absorption Lines ◽  
Radio Observations ◽  
Interstellar Absorption ◽  
Peak Intensity

The detailed relationship between optical interstellar absorption lines and 21-cm. observations is investigated in this paper.Dr Guido Münch, of the Mount Wilson and Palomar Observatories, provided the list of six intermediate-latitude stars shown in Table 1. The spectra of these stars all show complex absorption lines due to interstellar Ca 11. The 21-cm. line is measurable in four of the six regions, although the peak intensity is low in each case. It is noteworthy that for the first two stars on the list the radio velocity agrees closely with the velocity of an intense optical component. In view of the great difference in angular resolution, the failure to find correspondence in every case is not surprising.

Interstellar absorption lines in the spectrum of 3C 273

1983 ◽  
Vol 274 ◽  
pp. 136 ◽  
Author(s):  
D. G. York ◽  
C. C. Wu ◽  
J. C. Blades ◽  
S. Ratcliff ◽  
L. L. Cowie ◽  
...  
Keyword(s):  
Absorption Lines ◽  
Interstellar Absorption

scholarly journals Hidden or missing outflows in highly obscured galaxy nuclei?

2019 ◽  
Vol 623 ◽  
pp. A29 ◽  
Author(s):  
N. Falstad ◽  
F. Hallqvist ◽  
S. Aalto ◽  
S. König ◽  
S. Muller ◽  
...  
Keyword(s):  
Line Emission ◽  
Far Infrared ◽  
Spectral Lines ◽  
Absorption Lines ◽  
Wide Angle ◽  
Vibrationally Excited ◽  
Molecular Outflows ◽  
Luminous Infrared Galaxies ◽  
The Galaxy ◽  
Central Regions

Context. Understanding the nuclear growth and feedback processes in galaxies requires investigating their often obscured central regions. One way to do this is to use (sub)millimeter line emission from vibrationally excited HCN (HCN-vib), which is thought to trace warm and highly enshrouded galaxy nuclei. It has been suggested that the most intense HCN-vib emission from a galaxy is connected to a phase of nuclear growth that occurs before the nuclear feedback processes have been fully developed. Aims. We aim to investigate if there is a connection between the presence of strong HCN-vib emission and the development of feedback in (ultra)luminous infrared galaxies ((U)LIRGs). Methods. We collected literature and archival data to compare the luminosities of rotational lines of HCN-vib, normalized to the total infrared luminosity, to the median velocities of 119 μm OH absorption lines, potentially indicating outflows, in a total of 17 (U)LIRGs. Results. The most HCN-vib luminous systems all lack signatures of significant molecular outflows in the far-infrared OH absorption lines. However, at least some of the systems with bright HCN-vib emission have fast and collimated outflows that can be seen in spectral lines at longer wavelengths, including in millimeter emission lines of CO and HCN (in its vibrational ground state) and in radio absorption lines of OH. Conclusions. We conclude that the galaxy nuclei with the highest LHCN − vib/LIR do not drive wide-angle outflows that are detectable using the median velocities of far-infrared OH absorption lines. This is possibly because of an orientation effect in which sources oriented in such a way that their outflows are not along our line of sight also radiate a smaller proportion of their infrared luminosity in our direction. It could also be that massive wide-angle outflows destroy the deeply embedded regions responsible for bright HCN-vib emission, so that the two phenomena cannot coexist. This would strengthen the idea that vibrationally excited HCN traces a heavily obscured stage of evolution before nuclear feedback mechanisms are fully developed.

A Discussion on astronomy in the ultraviolet - The Celescope survey and the galactic distribution of interstellar absorption

1975 ◽  
Vol 279 (1289) ◽  
pp. 345-354 ◽  
Keyword(s):  
Interstellar Dust ◽  
Interstellar Extinction ◽  
Astronomical Observatory ◽  
Digital Television ◽  
National Observatory ◽  
Interstellar Absorption ◽  
The Galaxy ◽  
Galactic Distribution

The Celescope experiment consisted of four 31 cm aperture telescopes equipped with digital television photometers, installed in the Orbiting Astronomical Observatory, launched 7 December 1968. We used this instrument to conduct a survey in four ultraviolet colours: U l (2100-3200 A), U2 (1550—3200 A), U3 (1350— 2150 A) and U4 (1050-2150 A). We have published the observational results in the Celescope catalog of ultraviolet stellar observations (Davis, Deutschman & Haramundanis 1973). I have studied these results, together with relevant ground-based data, to determine the distribution of interstellar dust and variations of the interstellar extinction law with the position in the galaxy. Results from the data contained in the Celescope catalogue have been prepared for publication (Peytremann & Davis 1974)- These results have now been refined and expanded to include new ground-based U, B, V, and H(3 photometry acquired at Kitt Peak National Observatory, as well as new observations by W. A. Deutschman and R. Schild at Cerro Tololo Inter-American Observatory

scholarly journals The Mg II Features Near 2800Å and Spectral Classification

1977 ◽  
Vol 4 (2) ◽  
pp. 363-364
Author(s):  
Yoji Kondo
Keyword(s):  
The Other ◽  
Absorption Lines ◽  
Spectral Features ◽  
The Sun ◽  
Spectral Classification ◽  
Interstellar Absorption ◽  
B Stars ◽  
The Core ◽  
Chromospheric Emission

The Mg II resonance lines at 2795.523 and 2802.698Å and their respective subordinate lines at 2797.989 and 2790.768Å are probably among the most prominent and interesting spectral features in the ultraviolet; they are perhaps the most significant in the mid-ultraviolet. They are also observable in one form or the other in stars of practically all spectral types. We shall discuss relatively high (about 0.4Å) resolution observations of these features.In the early spectral types both the resonance and subordinate lines are seen primarily as absorption lines. An interstellar absorption of varying strengths is superimposed on the photospheric absorption of the resonance lines. The strengths of the photospheric resonance and subordinate lines increase from 0 to B, e.g., Lamers et al. (1973) and Kondo et al. (1975). The subordinate lines begin to merge with the resonance lines in late-B stars. In mid-A type stars, the resonance and subordinate absorption strengths become maximum. In F-type stars, the photospheric absorption strenghts continue to decrease. Chromospheric emissions become definitely detectable in F-type stars (Kondo et al. 1972). In a G2 V star, the sun, the chromospheric emission is fairly prominent at the core of relatively weak photospheric absorption. In K and M-type stars, this region is presumably dominated by the chromospheric emissions of Mg II resonance lines with the photospheric absorption becoming negligible in late-K stars; the only extant observation in this region is that of e Eri (K2 V) (McClintock et al. 1975).

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