Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted

Details Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted

1994-10-27

arxiv.org/abs/astro-ph/9410086v1

Astronomy and Astrophysics

Astrophysics

uuencoded Postscript file (including figures) -- MPIfR Preprint 598

Scientific paper

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 $\propto \nu^{1/3}$, attains a maximum at $\nu_max \ga 600 GHz$ 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 $\nu \la 100 GHz$, 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 $30\arcsec$ (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

Affiliated with

Also associated with

No associations

Rating

Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anatomy of the Sagittarius A complex: IV. Sgr A* and the Central Cavity revisi- ted will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-280661