Star Clusters: Confirmation of Stellar Evolution Open and Globular Clusters Ages of Clusters
Star Clusters in the Galactic Center
description
Transcript of Star Clusters in the Galactic Center
Star Clusters in the Galactic Center
Sgr A* at 30 WorkshopGreen Bank W.Va
March 25, 26, 2004
Donald F. FigerSTScI
CollaboratorsMassive Stars
Paco Najarro, CSICTom Geballe, GeminiRolf Kudritzki, UH
IMFAndrea Stolte, UFPavel Kroupa, U. Kiel Carsten Weidner, U. Kiel
Stellar VelocitiesMark Morris, UCLAEric Becklin, UCLAIan McLean, UCLA
Cluster DynamicsSungsoo Kim, KHU
Star Formation History in GCMike Rich, UCLAGene Serabyn, JPL
Science Questions• What is the most massive star that can form?• Is the IMF universal?• What is the evolutionary sequence for massive stars?• What causes massive stars to "erupt"?• What is the star formation history of the Galactic Center?• How do super-star clusters form?• How do super-star clusters affect their environments?• What is the dynamical evolution of massive clusters?• What is the connection between nuclear star formation
and massive central black holes?
GC Young Star Geography
Yusef-Zadeh, Morris, Chance 1984; Lang, Morris, Echevarria 1999
20 cm
N
E
60 p
c
Galactic Center: ExtinctionK band
Figer 1995
V band
Digitized Sky Survey
60 p
c
N
E
Galactic Center Clusters
CentralCluster
N
E
Quintuplet Cluster
1 pc
Pistol StarArchesCluster
The Central Cluster
Schoedel et al. 2002; Genzel et al. 2003
Central cluster: Massive Stars
Genzel et al. 2000; Krabbe et al. 1991, 1995
Central cluster: High Resolution Spectra
Figer et al. 2004, in prep.
Central cluster: Radial Velocities
Figer et al. 2003
Radial Velocity Project
Radial Velocity Project
Lick 3-m Figer 1995, PhD Thesis
Arches Cluster
Keck I 10-m Serabyn, Shupe, & FigerNature 1998, 394, 448
Arches Cluster
HST/NICMOS Figer et al. 1999, ApJ. 525, 750
Arches Cluster
VLT NAOS/CONICAStolte, A. 2003, PhD Thesis, University of Heidelberg
Arches Cluster
Arches Cluster: P-alpha
19”
= 0
.75
pc
see also:
Nagata et al.1995Cotera et al.1996Blum et al. 2001
Figer et al. 2002, ApJ, 581, 258
Arches stars: WN9 stars
He
I
He
I
He
I/H
I
NII
I
He
II
NII
I
NII
I
Figer et al. 2002, ApJ, 581, 258
Arches stars: O stars
68
27
HI
HeI
Figer et al. 2002, ApJ, 581, 258
Arches Cluster Mass Function
Stolte et al. 2002
HST/NICMOS VLT/NAOS/CONICA
Arches Cluster: Mass Segregation
Figer et al. 1999, ApJ, 525, 750
Arches Cluster: Upper Mass Cutoff
Figer 2003, IAU 212
1000 M!
Evidence for an upper masscutoff to the IMF
>20 stars
Quintuplet cluster
Quintuplet cluster: Massive Stars
Figer, Najarro, & Kudritzki 2004, in prep.
Quintuplet-proper Members: DWCLs?
L~104.6 L
T~700 K
R~250 AU
WR Movie from Monnier, Tuthill, & Danchi 2002, ApJ, 567, L137
Figer et al. 1999, ApJ, 525, 759
WC stars
• Observing on the Rayleigh-Jeans tail:
Can we guess the animal by observing its tail?
Pistol Star: Estimating the Luminosity
1 um+
Beware!
Pistol Star: Estimating the Luminosity
1 um+
Figer et al. 1999, ApJ, 525, 759
Pistol Star: Spectrum
Pistol Star: Mass
JHKLMN+
D.M.+
temperature
Lum.
Lum.+
modelMass
tracks by Langer
Figer et al. 1998, ApJ, 506, 384
2 Myr
Figer et al. 1999, ApJ, 525, 759
LBVs in the Quintuplet
Geballe et al. 2000, ApJ, 530, 97
FMM362
• Both the Pistol Star and FMM362 are Luminous, Blue, and Variable
Pistol Star
• Claim• 1-7 LPistol
• 150-1000 Msun
• Primary uncertainties• distance• temperature• singularity
• Figer, Najarro, Kudritzki• in prep• R=22000 1.5-4.2 um• NIRSPEC/Keck
LBV 1806-20
Figer, Najarro, Kudritzki 2004, in prep.
LBV 1806-20 is a binary?
Massive Stars in GC
WC WN LBV O RSG
Quintuplet 11 5 2 100 1Arches 0 6 0 160 0Center 15 15 5 100 2Other 2 2 0 ? ?Total 28 28 7 360 3
Galaxy 101 134 13 ? ?
red is estimate
Star Formation History in the GC
Figer et al. 2004, ApJ, 601, 319
Conclusions
• Massive GC clusters continuously likely form, disperse, and populate the region.
• Most massive/compact young clusters in the Galaxy are in the GC
• IMF is flat (at least in one cluster), and upper mass cutoff might be observed
• The Pistol Star and FMM362 are amongst the most massive stars in the Galaxy