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H 3 +. Search for hot and bright stars for H 3 + spectroscopy Near the Galactic center. Takeshi Oka. Department of Astronomy and Astrophysics and Department of Chemistry The Enrico Fermi Institute, University of Chicago. and T. R. Geballe. Gemini Observatory. - PowerPoint PPT Presentation
Transcript of H 3 +
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+
