The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics, and Formation

By T. Paumard, R. Genzel, F. Martins, S. Nayakshin, A. Beloborodov, Y. Levin, S. Trippe, F. Eisenhauer, T. Ott, S. Gillessen and 15 more. 2006

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We report the definite spectroscopic identification of ≃40 OB supergiants, giants, and main-sequence stars in the central parsec of the Galaxy. Detection of their absorption lines has become possible with the high spatial and spectral resolution and sensitivity of the adaptive optics integral field spectrometer SPIFFI/SINFONI on the ESO VLT. Several of these OB stars appear to be helium- and nitrogen-rich. Almost all of the ≃80 massive stars now known in the central parsec (central arcsecond excluded) reside in one of two somewhat thick (⟨ /R⟩ ≃ 0.14) rotating disks. These stellar disks have fairly sharp inner edges (R ≃ 1′′) and surface density profiles that scale as R-2. We do not detect any OB stars outside the central 0.5 pc. The majority of the stars in the clockwise system appear to be on almost circular orbits, whereas most of those in the "counterclockwise" disk appear to be on eccentric orbits. Based on its stellar surface density distribution and dynamics, we propose that IRS 13E is an extremely dense cluster (ρcore ≳ 3 × 108 M☉ pc-3) that has formed in the counterclockwise disk. The stellar contents of both systems are remarkably similar, indicating a common age of ≃6 ± 2 Myr. The K-band luminosity function of the massive stars suggests a top-heavy mass function and limits the total stellar mass contained in both disks to ≃1.5 × 104 M☉. Our data strongly favor in situ star formation from dense gas accretion disks for the two stellar disks. This conclusion is very clear for the clockwise disk and highly plausible for the counterclockwise system.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/05b4c5d0a5c09d64b48c0e029bc94872ff957958

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Citations in the corpus

MONITORING STELLAR ORBITS AROUND THE MASSIVE BLACK HOLE IN THE GALACTIC CENTER (2008, background): “This addresses for example the so-called ’paradox of youth’ for the stars in the central arcsecond (Ghez et al. 2003) or the puzzling existence of a large number of O-stars and Wolf-Rayet stars in the GC (Paumard et al. 2006).”
On the rate of black hole binary mergers in galactic nuclei due to dynamical hardening (2017, background): “There exists tentative evidence for a secondary counterclockwise disk made up of stars similar in their photometric, spectroscopic and kinematic properties (e.g. Paumard et al. 2006; Bartko et al. 2009).”
The nuclear star cluster of the Milky Way: proper motions and mass (2009, background): “This anisotropy is related to the presence of young, massive stars, a significant fraction of which shows coherent motion within one (or possibly two) stellar disks (Levin & Beloborodov 2003; Genzel et al. 2003; Lu et al. 2006; Paumard et al. 2006).”
The physics of galactic winds driven by active galactic nuclei (2012, background): “Interestingly, observations also reveal that a starburst in the central parsec occurred 6± 2 Myr ago (Paumard et al. 2006), perhaps accompanied by an accretion event onto Sgr A?”
Massive Perturber-driven Interactions between Stars and a Massive Black Hole (2006, background): “Table (3) compares the number of captured young stars in steady state, for the different MP models, on ther < 0.04 pc scale (the S-cluster) and 0.04< r < 0.4 pc scale (the stellar rings) with current observations (Eisenhauer et al. 2005; Paumard et al. 2006).”
A DISK OF YOUNG STARS AT THE GALACTIC CENTER AS DETERMINED BY INDIVIDUAL STELLAR ORBITS (2008, methodology): “Over this region, Paumard et al. (2006) note that all young stars brighter than K=13.5 should be identified, which includes OB giants and supergiants.”
Submillimeter Galaxies at z ~ 2: Evidence for Major Mergers and Constraints on Lifetimes, IMF, and CO-H2 Conversion Factor (2008, background): “In the central parsec of the Milky Way, Nayakshin & Sunyaev (2005) and Paumard et al. (2006) infer 1.”
Surface brightness profile of the Milky Way’s nuclear star cluster (2014, background): “In fact, a disc of young stars is observed in the GC right now (e.g., Levin & Beloborodov 2003; Paumard et al. 2006; Lu et al. 2009).”
LINE DERIVED INFRARED EXTINCTION TOWARD THE GALACTIC CENTER (2011, methodology): “We use only stars which have been spectroscopically identified as early-type (Paumard et al. 2006; Bartko et al. 2009).”
The structure of the nuclear stellar cluster of the Milky Way (2006, methodology): “We also have to consider the star formation that takes place in the inner 0.5 pc. Paumard et al. (2006) estimate a mass of ∼104 M for the young stars that formed in the most recent star burst event(s).”
HIGH ANGULAR RESOLUTION INTEGRAL-FIELD SPECTROSCOPY OF THE GALAXY'S NUCLEAR CLUSTER: A MISSING STELLAR CUSP? (2009, methodology): “For example, the density of bright young stars falls off relatively steeply as R−2 (Paumard et al. 2006; Lu et al. 2009, but see also Buchholz et al. (2009)).”
What drives the growth of black holes (2011, background): “…the growth of the BH; indeed, the presence of nuclear stellar rings close to the BH in nearby quiescent galaxies provide indirect evidence in support of this hypothesis (e.g., Nayakshin & Sunyaev, 2005; Bender et al., 2005; Paumard et al., 2006; Schödel et al., 2007; Hopkins & Quataert, 2010).”
The most massive stars in the Arches cluster (2007, methodology): “Studying the dynamics of these young stars, Paumard et al. (2006) (see also Levin & Beloborodov 2003; Genzel et al. 2003) have shown that they orbit SgrA* in two counter-rotating disks.”
A New Distortion Solution for NIRC2 on the Keck II Telescope (2016, background): “…of the supermassive black hole and studies of its surrounding stellar population (e.g., Eckart & Genzel 1997; Ghez et al. 1998, 2005; Genzel et al. 2003; Paumard et al. 2006; Stolte et al. 2008; Bartko et al. 2009; Lu et al. 2009; Clarkson et al. 2012; Meyer et al. 2012; Yelda et al. 2014).”
STAR FORMATION IN THE CENTRAL 400 PC OF THE MILKY WAY: EVIDENCE FOR A POPULATION OF MASSIVE YOUNG STELLAR OBJECTS (2009, background): “This region contains some of the most spectacular young and dense stellar clusters having an age of a few million years (Figer et al. 1999; Paumard et al. 2006; Lu et al. 2006).”
First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer (2017, background): “9 mag, Paumard et al. 2006), for fringe-tracking and observed GC IRS 16C ( m K = 9 .”
Composition of the galactic center star cluster - Population analysis from adaptive optics narrow band spectral energy distributions (2009, background): “We can also confirm the much flatter KLF found for the early type stars (e.g. Paumard et al. 2006) to a much greater depth (K<15.5 instead of K<13-14).”
Peering through the veil: near-infrared photometry and extinction for the Galactic nuclear star cluster (2009, methodology): “Many early-type stars reported by Paumard et al. (2006); Buchholz et al. (2009); Do et al. (2009a) and other authors are correctly identified.”