| | |
| | |
Stat |
Members: 3645 Articles: 2'501'711 Articles rated: 2609
20 April 2024 |
|
| | | |
|
Article overview
| |
|
Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted | R.Zylka
; P.G.Mezger
; D.Ward-Thompson
; W.J.Duschl
; H.Lesch
; | Date: |
27 Oct 1994 | Abstract: | We present submm images of Sgr A* and its surroundings obtained at 800, 600 and 450 $mu$m with the JCMT and derive flux densities of Sgr A* at all three wave- lengths. Combined with upper limits by Gezari and associates at MIR wavelengths a time averaged radio spectrum is obtained which increases $propto
u^{1/3}$, attains a maximum at $
u_max ga 600 GHz$ and must decrease rapidly at fre- quencies $ga 10^4$GHz. This spectrum allows for about $3 M}_odot$ of 50K dust and associated hydrogen in the telescope beam. While variations on time-scales of a few months are now well established for the frequency range $
u la 100 GHz$, our investigation of variability at higher frequencies still yields only marginal results. The Circum-Nuclear Disk (CND) extends over the central 12 pc. At the galactocentric radius $R sim 1 pc$ dust and hydrogen column densities drop to low values and form the Central Cavity. Our submm images show that the bottom of this cavity is rather flat. Variations in the dust emission are just consistent with the detection of a `Tongue’ of $sim 200 M_odot$ of atomic hydrogen reported by Jackson et al. (1993) to be located between the Northern and the Eastern Arm of the Minispiral. We present a revised submm/IR spectrum of the central $30arcsec$ (R$la 0.6 pc$) with flux densities corrected for an interstellar extinction of $A_v sim 31 mag$. This spectrum attains its maximum at $lambda sim 20 mu m$ and comes from dust with temperatures $sim 170 - 400 K$ which is associated with the Eastern Arm and the East-West Bar. The in- tegrated luminosity is $sim 5 10^6 L_odot$ to which emission at $lambda la 30 mu m$ contributes $sim 80\%$. Heating of this dust is not provided by a central source but rather by a cluster of hot ($T eff sim 3 - 3.5 10^4 K$) and luminous stars which could include the He{sc i}/H{sc i}-stars detected by | Source: | arXiv, astro-ph/9410086 | Services: | Forum | Review | PDF | Favorites |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
| News, job offers and information for researchers and scientists:
| |