Radio Searches for Interstellar Carbon Chains HC 4 OH and H 2 CCC

Transcription

1 Radio Searches for Interstellar Carbon Chains HC 4 OH and H 2 CCC Tokyo Univ. of Science a Nobeyama Radio Observatory b Shizuoka Univ. c Sophia Univ. d M. Araki, a S. Takano, b H. Yamabe, a N. Koshikawa, a K. Tsukiyama, a A. Nakane, c T. Okabayashi, c A. Kunimatsu, d N. Kuze d

2 Radio Searches for Interstellar Carbon Chains HC 4 OH and H 2 CCC I. A Search for the Interstellar Linear Carbon-Chain Alcohol HC 4 OH in the Star-Forming Region L1527 and the Dark Cloud TMC-1 II. Radio Search for H 2 CCC toward HD as a Candidate of Diffuse Interstellar Band Carrier

3 1. Introduction Chemical Composition of Interstellar Space Interstellar Molecules 163 species* Linear Carbon Chain: 33 species Alcohol: MeOH, EtOH, Vinyl Alcohol Linear Carbon-Chain Alcohol : New Category HC 4 OH: Candidate of a New Interstellar Molecule 2007 Sophia Univ. Stark-Modulation MW Spectroscopy 2010 Shizuoka Univ. FT-MW Spectroscopy * Search for HC 4 OH

4 2. Observations Target clouds Rich carbon chains Rich O bearing molecules Low-mass star-forming region L1527 Dark cloud TMC-1 *

5 Observed Molecules in L1527 *

6 Taurus Galactic Plane Orion The equinoctial Outdoor sky map 2000 TMC-1 L1527 R.A. (J2000) 4h 41m 42.49s 4h 39m 53.89s Decl. (J2000) 25d 41' 27".0 26d 03' 11".0

7 Taurus Dark-Clouds Region TMC-1 Galactic Latitude [degree] L1527 Light Extinction Galactic Longitude [degree] Tokyo Gakugei University,

8 Telescope Date Integration Time Search Deepness Nobeyama Radio Observatory 45m Telescope 2009/04/11-17 L1527, TMC /01/15-21 L /03/04-05 L1527 1~2 h Several mk in Antenna Temp.

9 Observed Transitions of HC 4 OH H22H30 S40 K a = 0 6K TMC-1 10K L1527 High-Resolution Search

10 Telescope Date Integration Time Search Deepness Nobeyama Radio Observatory 45m Telescope 2009/04/11-17 L1527, TMC /01/15-21 L /03/04-05 L1527 1~2 h Several mk in Antenna Temp.

11 Observed Lines GHz HC 4 OH a J Ka,Kc = 5 0,5 4 0, HC 5 N J = b 42.6 J Ka,Kc = 7 0,7 6 0, C 4 H N J = J Ka,Kc = 9 0,9 8 0, N J = J Ka,Kc = 10 0,10 9 0,9 J Ka,Kc = 11 0, , b N J = b N J = b Sakai et al. 2008, 2009 a Kuze et al. in preparation.

12 3. Results and Discussion

13 L GHz T A * (K) HC 4 OH No Detection 38.3 TMC V LSR (kms -1 ) 21.3 V LSR (kms -1 )

14 L GHz

15 Distribution of HC 4 OH in L1527 T A * (K) HC 5 N J = GHz NRO HC 4 CN (HC 5 N) = HC 4 OH V LSR (kms -1 ) Integrated Intensity Kkms -1 NRO 45 m 38.9" Kkms -1 GBT 100 m 17.5" 33" Sakai et al. 2009

16 Upper Limits of HC 4 OH Column Densities 3σ noise level Column Density/ cm -2 L1527 TMC-1 HC 4 OH < < C 4 H * HC 5 N * ** Excitation Temperature/ K HC 4 OH 12.3 fix(c 4 H 2 *) 3.8 fix(c 4 H 2 *) C 4 H * HC 5 N 14.7* 6.5** (Local Thermal Equilibrium), *Sakai et al., 2008&2009, **Takano et al. 1990

17 Column Density Ratios L1527 TMC-1 [HC 5 N]/ [C 4 H] 1/15 1/5 [HC 4 OH]/[HC 5 N] <0.3 <0.1 [HC 4 OH]/[C 4 H] <1/52 <1/52

18 What is a contribution to chemical reaction from the ratios? No chemical reactions for HC 4 OH are reported.

19 Two schemes for Chemical Reactions of HC 4 OH O/OH reacts with a carbon chain. OX (+) + C 4 X (+) XC 4 OX (+) HC 4 OH O/OH extends a carbon chain. OX (+) XC 2 OX (+) XC 4 OX (+) HC 4 OH The HC 4 OH/C 4 H ratio can contribute to know the chemical reactions of HC 4 OH.

20 4. Summary Deep Search of HC 4 OH in L1527 and TMC-1 Upper limits of HC 4 OH < cm -2 HC 5 N > HC 4 OH C 4 H >> HC 4 OH Chemical Reactions of HC 4 OH

21 Radio Searches for Interstellar Carbon Chains HC 4 OH and H 2 CCC I. A Search for the Interstellar Linear H Carbon-Chain Alcohol HC 4 OH in the C C C Star-Forming Region L1527 and the H Dark Cloud TMC-1 II. Radio Search for H 2 CCC toward HD as a Candidate of Diffuse Interstellar Band Carrier

22 1. Introduction Diffuse Interstellar Bands Electronic transition A or B Absorption X Diffuse Interstellar Bands: DIBs Absorption lines by interstellar molecules Diffuse Interstellar Bands (DIBs) First report in 1922 Optical ~NIR (width:1-100 cm -1 ) ~600 lines No identification so far 2015/2/20 22

23 H 2 CCC as a Diffuse Interstellar Band Carrier Maier et al., ApJ, 726, 41 (2011). Mass selected H 2 CCC 6K Ne-Matrix, Absorption spectra C C C H H H 2 CCC D 2 CCC B allowed A forbidden X

24 Cavity Ring Down Spectra Jet, High Resolution 5450Å 4881Å H 2 CCC? H 2 CCC + l-c 3 H D 2 CCC l-c 3 H removed Maier et al Validation: Stanton et al Negative ion photoelectron spectroscopy + Theoretical calculations

25 DIBs and Laboratory Spectra DIB at 4881 Å DIB at 5450 Å DIBs at 5450 and 4881 Å Agreements in widths, wavelengths and profiles Column density: cm -2 Maier et al. 2011

26 Excitation Temperature Maier et al. (2011) Lab. 60 K Upper state life time 100 fs Diffuse Clouds Temp.: 10-60K

27 Opinion 1 Oka & McCall, Science, 331, 293 (2011). Agreements in diffuse peaks DIBs are not toward the same star. DIBs are not by the same cloud. Too much abundances as H 2 CCC(>>C 2 )

28 Opinion 2 Strong variability HD Toward 49 stars H 2 CCC Krełowski et al., ApJ, 735, 124 (2011)

29 Blending? H 2 CCC pure blending HD H 2 CCC?

30 How to Judge the Identification Maier et al. Oka & McCall Yes No Krełowski et al. No blending? Dipole Moments: D H 2 CCC has been detected in dark clouds by radio observations. Radio observations of H 2 CCC toward HD Column density: cm -2 (Maier et al. 2011) Excitation temperature: K J Ka,Kc = 5 1,5 4 1,4 : GHz Antenna temperature: ~2 K

31 2. Observations The 45 m telescope in Nobeyama Radio Observatory Date: 2012 January 15 J Ka,Kc = 5 1,5 4 1,4 : GHz Receiver: S100 Integration: 1h25m Antenna Temp.: 32 mk

32 HD HD galactic plane [α(j2000), δ(j2000)] = (19h 27m 26s.56, ) The 7th magnitude star

33 Two diffuse clouds toward HD McCall et al., ApJ, 567, 391, (2002) Velocity: 7.7 and 23.6 km s 1 HD CH CH 4300Å CH Linewidths (FWHM): 7.7 and 4.9 km s 1

34 Possible line profile of H 2 CCC Arbitrary Intensity Components by Frequency Throw

35 3. Results and Discussions Integration: 1h25m Antenna Temp.: 32 mk

36 Upper limit of column density Ortho/Para = 3.0 Permanent dipole moment = D Excitation temp. = K Column density ratio = 40:60 (CH) Velocity of 23.6 km s 1 3σ rms noise = 95 mk Linewidth of 4.9 km s 1 (CH) σ= 95 mk Upper limit of column densities H 2 CCC Ortho + Para 23.6 kms kms K cm 2 60 K cm 2

37 Toward HD The upper limit of a column density is cm 2. DIB at 5450 Å < 1 25 Å The huge column density ( cm -2, Maier et al. 2011) of H 2 CCC toward HD was unjustified.

38 How about toward other stars? H 2 CCC pure blending HD Assumption: HD has a normal column density for H 2 CCC. The major carrier of DIBs at 5450 and 4881 Å can not be H 2 CCC.

39 4. Summary We searched for the rotational transition of H 2 CCC at 103 GHz toward HD using the 45 m telescope at NRO. The upper limit of a column density toward HD is cm 2. The huge column density of H 2 CCC toward HD (Maier et al. 2011) was unjustified. The major carrier of DIBs at 5450 and 4881 Å can not be H 2 CCC. C C C H H