Discovery of Massive Young Stellar Objects in the Galactic Center with Warm CO2 Gas Absorption
Deokkeun An (IPAC/Caltech)
Solange Ramirez (IPAC/Caltech)
Kris Sellgren (Ohio State U.)
et al., 2009, ApJL, submitted
Galactic Center: Central Molecular Zone = central ~200 pc
Star formation conditions unique because tidal shear, high gas pressure
Evidence for recent star formation:
Compact H II regions
Young star clusters (1—8 Myr old)
Search for candidate Young Stellar Objects (YSOs) with Spitzer IR images + Spitzer IR spectra
Warm molecular gas in massive YSO in the Galactic Center
DeokkeunAn, Ramirez, Sellgren, et al. ApJL, submitted
Warm C2H2 HCN CO2 gas
(absence of [Ne III] gas)
Gas-Phase Absorption from C2H2, HCN, CO2
GC YSO model fits:T = 100—400 KX(HCN) = 2—70 x10-7
Sgr B2: T = 100—200 K X(HCN) = 0.2—0.7 x10-7
Conclusions:Spectra of GC YSO candidates show warm CO2, HCN, C2H2 gas in absorption
Spectra also show solid-phase CO2, H2O, silicate dust
CO2 ice profile suggestive of high CH3OH ice abundance
Molecular abundances comparable to other massive YSOs, much larger than towards Sgr B2 or TMC-1
Collaborators:Adwin Boogert (Caltech)
Richard Arendt (NASA/Goddard)
Angela Cotera (SETI Institute)
Thomas Robitaille (St. Andrews U.)
Mathias Schultheis (Besancon Obs.)
Howard Smith (CFA)
Susan Stolovy (SSC/Caltech)