The orbit of S2
Dance of Stars
The image summarizes the central parsec (23") of our Galaxy in the near infrared
and the kind of data that are available:
Center: 0.15" K-Band image taken with the
SHARP camera on the ESO-NTT.
Right, top and bottom left insets: K-band spectra of
several of the stars (blue supergiants, red supergiants/AGB stars)
and of the SgrA* region (circled), taken with the MPE 3D
spectrometer and with ISAAC.
Bottom left: The embedded, presumably very young star IRS 1 has a
reddened, featureless spectrum (the
Br gamma emission line is due to the ionized gas of the so-called
"mini-spiral" in the central parsec).
Top: Spectrum of the HeI
emitting star IRS 16C, that forms part of the IRS 16 complex of
bright, young HeI emitting stars close to SgrA*.
Top and bottom
right: CO absorption features in the spectra of IRS 7 and IRS 14N.
Middle right insets: Spectra of the Wolf-Rayet star, IRS 13E, and of
the SgrA* cluster. The spectrum of the northern part of the SgrA*
cluster suggests that its brighter members are main sequence OB V
Left and top left insets. Proper motions in the center
of the Galaxy, obtained with the MPE SHARP camera on the ESO NTT.
Shown are the proper motion vectors superposed on a 0.15"
SHARP/NTT 2µm image of the central ~10" (top, cross is
SgrA*) and on a 0.05" Keck image of the central 1" region
around SgrA* (bottom, asterisk denotes position of SgrA*).
The combination of observations of Sgr A* in different wavelength regimes (from X-ray to radio) allows a description of the spectral energy distribution of the emitted radiation and the construction of emission models.
Spectral energy distribution of the
emission from Sgr A*. This plot shows the extinction and absorption
All error bars are ±1 sigma and include statistical and
systematic errors. Black triangles denote the radio spectrum of
Sgr A*. Open grey circles mark various
infrared upper limits from the literature. The three
X-ray data ranges are (from bottom to top) the quiescent state as
determined with Chandra (black; Baganoff et al., 2003), the autumn
2000 Chandra flare (red; Baganoff et al., 2000), and the autumn 2002
flare observed by XMM (light blue; Porquet et al., 2003). Open red
squares with crosses mark the de-reddened peak emission (minus
quiescent emission) of the four NIR flares. Open blue circles mark the de-reddened H,
KS, and L' luminosities of the quiescent state,
derived from the local background subtracted flux density of the
point source at the position at Sgr A*, thus eliminating the
contribution from extended, diffuse light due to the stellar cusp
around Sgr A*.
© Infrared and Submillimeter Astronomy Group at MPE
24/11/2008, editor of this page: Thomas Ott