H3+

Search for hot and bright stars for

H3+ spectroscopy

Near the Galactic center

Takeshi Oka

Department of Astronomy and Astrophysicsand Department of Chemistry

The Enrico Fermi Institute, University of Chicago

and T. R. GeballeGemini Observatory

OSU international symposium on molecular spectroscopy, June 25, 2009

(2,2)

(3,3)

(1,1)

(2,2)

(3,3)

(1,1)

8 stars within 30 pc from GCall show the warm and diffuse gas

T = 220 - 400 Kn ≤ 100 cm-3

Goto, Usuda, Nagata, Geballe, McCall, Indriolo, Suto, Henning, Morong, Oka, ApJ, 688, 306 (2008)

A lucky summer at the Gemini South Observatory

The great ocean of truth lay all undiscovered before us

We must find hot and bright young stars !

Long pathlength of H3+

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

Typical hot young star and cool old star (both very bright!)

Hot Cool

Spectra taken by UIST spectrometer of the UKIRT

CO 2 – 0 3 – 1 4 – 2 5 – 3

Medium resolution spectroscopy at UKIRTusing UIST spectrometer

# Star Spectrum location

1 J 17432173 728_24 K=6.5 L=3.8 132 pc West 2 J 17432988 808_56 K=8.8 L=4.5 127 pc West 3 J 17441867 728_28 K=10.0 L=6.4 80 pc West ? 4 J 17444083 731_64 K=9.4 L=6.4 45 pc West 5 J 17450483 815_33 K=9.0 L=6.5 30 pc West 6 J 17452861 815_71 K=9.2 L=6.6 10 pc out of plane 7 J 17461514 731_68 K=10.1 L=5.6 Close to Quint. 8 J 17461783 731_72 K=7.8 L=5.5 Close to Quint. 9 J 17463219 728_40 K=9.2 L=6.4 43 pc East10 J 17470264 808_143 K=10.2 L=6.5 ??11 J 17470898 815_79 K=10.4 L=6.6 84 pc East.12 J 17474486 731_76 K=10.3 L=4.7 96 pc East

Candidate stars

High resolution spectroscpy for radial location

The central 2 pc Circum nuclear disk Adaptive Optics needed VLT, Subaru

The central 30 pc Super-massive clusters Velocity analysis GS

Whole CMZ Hunting stars UKIRT Observation Subaru, GS

Tons of work ahead of us

→ IRTF→ SOAR

Radio CO, CS, HCN, CH emission

H3+ IR abs.

Understanding a monster

X-ray γ-ray

HII regionRadio recomb.Fine structure

Radio continuum

H2 FIRH2 IR emission

CO IR abs

H3+