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Why Chemistry? Satoshi Yamamoto Nami Sakai, Yoshimasa Watanabe, Department of Physics, The Univ. of…

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Line Survey of TMC-1 with NRO 45 m Kaifu et al. (2004) HC 3 N HC 5 N HC 7 N CCS, CCCS, c-C 3 H, CCO, CCCO, C 4 H 2, etc

Text of Why Chemistry? Satoshi Yamamoto Nami Sakai, Yoshimasa Watanabe, Department of Physics, The Univ....

Chemistry










2
Kaifu et al. (2004)
H3+, HCO+, HN2+, HCS+, C6H-
HC3N, HC5N, HC7N, HC9N, HC11N
C2H, C3H, C4H, C5H, C6H, C8H, CCS, C3S
CH3OH, HCOOCH3, (CH3)2O, C2H5CN,
1/τ1/tf + 1/td
H3+ + X → HX+ + H2 a few 105 yr
td: Time Scale for Destruction of Molecules
Av > 5 Ionic Destruction slow > 106 yr
c.f. Reactions with He+, H+, etc.
Av < 3 Photodissociation fast 102 yr
In Actual Cloud Cores
Observed Spectrum
Physical Condition
in the low-mass protostar IRAS 16293-2422
Cazaux et al. 2003Bottinelli et al. 2004; Kuan et al. 2004
HCOOCH3
C2H5CN
HCOOCH3
Another NEWS:
Eu = 21 K
N=9-8, F2
Efficient Production of Various Carbon-Chain Molecules around the Protostar
Triggered by Evaporation of Methane from Grain Mantles
(Warm Carbon Chain Chemistry)(Sakai et al. 2008; 2009; 2010)
Discovery of Carbon-Chain Rich Protostar Sakai et al. (2008, 2009)
e.g.) CH4 + C+ C2H3+ + H
C2H3+ + e C2H + H + H - - - -
Hot Corino
WCCC source
One possibility is the difference in prestellar collapse.
Carbon is depleted as CO. On the other hand Carbon is depleted as C, In order to asses this possibility, various mol. including deuterated spieces should be observed.
Tentative Detection of Deuterated Methane
2012
18
Line Survey of Low-mass Protostars with ASTE (Watanabe et al.)
Hot Corino
Star Formation
Survey toward Many Sources
(2) Wide Frequency Coverage
(3) Large Instantaneous Bandwidth
(4) Reliable Observations
Observing Frequency
Full Aperture (50 m)
Medium Aperture (30 m)
Fundamental Species (H2D+, HD2+, NH, NH2 etc.)
Small Aperture (15 m)
Example of Observing Mode
5-6 sets are necessary to cover the whole band.
(2) 92-100 GHz
2-3 sets are necessary to cover the two bands.
Roles of Large Single Dish
Finding ‘New’ Sources rather than Ordinary Sources
Obtaining Large/Complete Statistical Data
Studying Large Scale Phenomena
Frequency Domain Survey → Chemical Diagnosis
Complimentary to ALMA
Why Chemistry?
Because it is crucial to understand evolution of matter in space.