Star Clusters in the Galactic Center Sgr A* at 30 Workshop Green Bank W.Va March 25, 26, 2004 Donald F. Figer STScI

Collaborators Massive Stars Paco Najarro, CSIC Tom Geballe, Gemini Rolf Kudritzki, UH IMF Andrea Stolte, UF Pavel Kroupa, U. Kiel Carsten Weidner, U. Kiel Stellar Velocities Mark Morris, UCLA Eric Becklin, UCLA Ian McLean, UCLA Cluster Dynamics Sungsoo Kim, KHU Star Formation History in GC Mike Rich, UCLA Gene 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 cm N E 60 pc

Galactic Center: Extinction K band Figer 1995 V band Digitized Sky Survey 60 pc N E

Galactic Center Clusters Central Cluster N E Quintuplet Cluster 1 pc Pistol Star Arches Cluster

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

Lick 3-m Figer 1995, PhD Thesis Arches Cluster

Keck I 10-m Serabyn, Shupe, & Figer Nature 1998, 394, 448 Arches Cluster

HST/NICMOS Figer et al. 1999, ApJ. 525, 750 Arches Cluster

VLT NAOS/CONICA Stolte, A. 2003, PhD Thesis, University of Heidelberg Arches Cluster

Arches Cluster: P-alpha 19” = 0.75 pc see also: Nagata et al.1995 Cotera et al.1996 Blum et al Figer et al. 2002, ApJ, 581, 258

Arches stars: WN9 stars HeI HeI/HI NIII HeII NIII Figer et al. 2002, ApJ, 581, 258

Arches stars: O stars HI HeI Figer et al. 2002, ApJ, 581, 258

Arches Cluster Mass Function Stolte et al HST/NICMOSVLT/NAOS/CONICA

Arches Cluster: Mass Segregation Figer et al. 1999, ApJ, 525, 750

Arches Cluster: Upper Mass Cutoff Figer 2003, IAU M  ! Evidence for an upper mass cutoff to the IMF >20 stars

Quintuplet cluster

Quintuplet cluster: Massive Stars Figer, Najarro, & Kudritzki 2004, in prep.

Quintuplet-proper Members: DWCLs? L~ 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. + model Mass tracks by Langer Figer et al. 1998, ApJ, 506, 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 L Pistol M sun Primary uncertainties distance temperature singularity Figer, Najarro, Kudritzki in prep R= um NIRSPEC/Keck LBV

Figer, Najarro, Kudritzki 2004, in prep. LBV is a binary?

Massive Stars in GC 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