Two Sightlines toward the Galactic Center with Remarkable H 3 + and CO Spectra Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry,

Two Sightlines toward the Galactic Center

with Remarkable H3+ and CO Spectra

Takeshi OkaDepartment of Astronomy and Astrophysics

and Department of Chemistry, The Enrico Fermi Institute, University of Chicago

June 24, Columbus Symposium

Tom Geballe Gemini Observatory

Geballe, T.R. & Oka, T. 2010, ApJ, 709, L70

Tomonori Usuda

Miwa Goto

Subaru Telescope

Max-Planck Institute for Astronomy

H3+ near the GC

Surprises

Huge column density; rich profile Geballe et al. ApJ 1999(3,3) metastable and (2,2) unstable H3

+ Goto et al. PASJ 2002Thermalization model analysis Oka & Epp ApJ 2004Revelation of warm and diffuse gas GS Oka et al. ApJ 2005Review Oka PNAS 2006From the center to 30 pc east Subaru Goto et al. ApJ 2008Scrutiny of the Central core VLT Goto et al. 2010Synthesis Gemini South Oka et al. 2011

30 pc

Lazio & Cordes, ApJ, 505, 715 (1998)

0.8 107-8 K

0.1 104-6 K 10 cm-3

0.1 50 K 104 cm-3

Previous concept of gas in the CMZneed to be drastically changed

Warm and diffuse gas250 K 102 cm-3

f: X-ray emittingUltrahot plasma

ζ·L

Old (late-type) stars are useless

Nagata, Hyland, Straw, Sato, Kawara, ApJ, 406, 501 (1993)

Bright and hot young stars are scarce

Search for bright and hot stars in the CMZGLIMPSE Point Source Catalogue of the Spitzer Space Telescope, L to M Ramírez et al. 2008, ApJS, 175, 147

2MASS photometry at J, H, and K bandsSkrutskie et al. 2006, AJ, 131, 1163

~ 2,000,000 stars

L < 7.5

~ 3,000 stars

(J – K)/(K – L) < 2.5K - L > 1.5J - K > 5

~ 300 stars

Low res. CO first overtone, 2.2 – 2.4μm

Candidate stars

Selected stars

High res. H3+ and CO spectroscopy

83 stars so far

10 new stars and 5 known stars

Star L J – K K – L (J – K)/(K – L)GCS3-2 3.03 7.33 3.16 2.32GCS4 3.71 7.65 3.45 2.22NHS21 4.62 7.03 2.76 2.55*NHS25 6.24 4.81* 1.27* 3.79*

brightness

youth

hotness

location

8

New bright and hot dust embedded stars suitable for H3

+ spectroscopy

Geballe and Oka, ApJ, 709, L70-73 (2010)

Two sightlines with remarkable H3+ spectrum

α

ι

Geballe and Oka, ApJ, 709, L70-73 (2010)

0 – 30 pc EastQuintuplet, α, ι

Geballe and Oka, ApJ 709, L70-73 (2010)

Iota, the Monster

“iota”, 85 pc East, Sgr B

High T

Low n

(3,3)

(2,2)

Subaru May 4, 2010

H3+ ν2←0 (2,2)l←(1,1)l

Iota 84.5 pc East 1.8 pc below

Gemini South

H2O+ 111←000 2B1

Sgr B2 101.1 pc East 1.4 pc above

HIFI

Ossenkoph et al. Astro-ph.1005, 2521, 2010

Two Monsters

“alpha”, 140 pc West, 2.7 pc below

Alpha, the elegant

Geballe and Oka, ApJ 709, L70-73 (2010) H. Liszt, ApJL, 82, 495 (1992)

13CO

Sgr E, 144 pc West, 20 pc above

αβ

“alpha”, 140 pc West, 2.7 pc below

Geballe and Oka, ApJ 709, L70-73 (2010)

Expanding Molecular Ring