THE STAR FORMATION HISTORY OF THE MILKY WAY'S NUCLEAR STAR CLUSTER

Journal Article · Thu Nov 10 00:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/2/108; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612688

Pfuhl, O; Fritz, T K; Eisenhauer, F; Genzel, R; Gillessen, S; Ott, T; Dodds-Eden, K ^[1]; Zilka, M; Sternberg, A ^[2]; Maness, H ^[3]

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1. Max-Planck-Institute for Extraterrestrial Physics, Giessenbackstrasse, D-85748 Garching (Germany)
2. Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)
3. Department of Physics, University of California, Berkeley, CA 94720 (United States)

We present spatially resolved imaging and integral field spectroscopy data for 450 cool giant stars within 1 pc from Sgr A*. We use the prominent CO bandheads to derive effective temperatures of individual giants. Additionally we present the deepest spectroscopic observation of the Galactic center (GC) so far, probing the number of B9/A0 main-sequence stars (2.2-2.8 M{sub sun}) in two deep fields. From spectrophotometry we construct a Hertzsprung-Russell diagram of the red giant population and fit the observed diagram with model populations to derive the star formation history of the nuclear cluster. We find (1) that the average nuclear star formation rate dropped from an initial maximum {approx}10 Gyr ago to a deep minimum 1-2 Gyr ago and increased again during the last few hundred Myrs, (2) that roughly 80% of the stellar mass formed more than 5 Gyr ago, and (3) that mass estimates within R {approx} 1 pc from Sgr A* favor a dominant star formation mode with a 'normal' Chabrier/Kroupa initial mass function for the majority of the past star formation in the GC. The bulk stellar mass seems to have formed under conditions significantly different from the young stellar disks, perhaps because at the time of the formation of the nuclear cluster the massive black hole and its sphere of influence were much smaller than today.

• OSTI ID: 21612688
• Journal Information: Astrophysical Journal, Vol. 741, Issue 2; Other Information: DOI: 10.1088/0004-637X/741/2/108; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BLACK HOLES
CARBON MONOXIDE
GIANT STARS
HERTZSPRUNG-RUSSELL DIAGRAM
INTEGRALS
LUMINOSITY
MAIN SEQUENCE STARS
MILKY WAY
SPECTROPHOTOMETRY
SPECTROSCOPY
STAR CLUSTERS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DIAGRAMS
GALAXIES
INFORMATION
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STARS