Line Survey of Low-Mass Star Forming Regions Satoshi Yamamoto, Nami - PowerPoint PPT Presentation

Line Survey of Low-Mass Star Forming Regions Satoshi Yamamoto, Nami Sakai, Takeshi Sakai, Shuro Takano, and NRO 45m Line Survey Group

Outline of this talk (1) Introduction (2) Chemistry of Class 0 sources (3) Line Survey with ALMA

Star Formation and Astrochemistry Chemical Evolution to Planets Chemical Diagnostics of Star and Planet Formation

Interstellar Molecules • H 2 • CO • HCN, HNC, H 2 CO, NH 3 , CS, SiO, CN, SO, SO 2 • H 3+ , HCO + , HN 2+ , HCS + , C 6 H - • HC 3 N, HC 5 N, HC 7 N, HC 9 N, HC 11 N • C 2 H, C 3 H, C 4 H, C 5 H, C 6 H, C 8 H, CCS, C 3 S • CH 3 OH, HCOOCH 3 , (CH 3 ) 2 O, C 2 H 5 CN, CH 3 CHO, HCOOH, C 2 H 5 OH, ～ 150 Species

Chemical Evolution of Molecular Clouds C → CO Conversion CO Depletion Mantle Evaporation Carbon Chains HN 2 + , NH 3 Deuterated Species DCO + , H 2 D + Complex Organic Molecules

Caselli et al. 2002 Ohashi et al. 1999 ＋

Formation of Complex Organic Molecules L1544 H Grain surface CO reaction CH 3 OH H H H H CO H 2 CO CO CO Cold Phase H 2 CO Gas phase CH 3 OH HCOOCH 3 reaction CH 3 OCH 3 Caselli et al. 1999 Hot Phase

HCOOCH 3 C 2 H 5 CN Cazaux et al. ApJ 593, L51 (2003)

● NGC1333 IRAS 4B ● Distance ； 220 pc ( Perseus ) ● Mass ； about 0.4 M ⊙ 0.4 M ⊙ ● Class 0 (a few 100 yr) Class 0 (Dynamical Time Scale of Molecular Outflow) Choi, M. 2001, ApJ, 553, 219) Detection of HCOOCH 3 On-source Integration Time : 18.5 h rms ; 3.6 mK Δ V ; A 1.2 km/s Center Frequency ； 89.3146 GHz T MB ; A 22 mK HCOOCH 3 E N. Sakai et al. PASJ 58, L15 (2006 ） V LSR ; A 7.1 km/s

Chemical Evolution of Molecular Clouds C → CO Conversion CO Depletion Mantle Evaporation Carbon Chains HN 2 + , NH 3 Deuterated Species DCO + , H 2 D + Complex Organic Molecules

L1527 Distance : ～ 140 pc ( Taurus ) Class 0 – Class I Luminosity : 2 L ⊙ cf : NGC1333 IRAS 4B Distance : ～ 220 pc Luminosity : 6 L ⊙ T A * = 11 mK (Obs.) Predicted T A * = 9.2 mK ν 0 ； 89.3146 GHz, HCOOCH 3 E Complex species were not detected （ NRO 45 m, 2005/12-2006/01 ） rms : 2.1 mK The on-source integration time : 22 h

Various Carbon-Chain Molecules in L1527 ★ l -C 4 H ★ c -C 3 H 2 ★ CH 3 CCH ( N = 9 – 8, E u = 21 K) (4 3, 2 – 4 2, 3 , E u = 29 K) ( J =5 – 4, K = 2, E u = 41 K) High Excitation Lines ! ★ l -C 3 H 2 (4 1, 3 – 3 1, 2 , E u = 23 K) @ 80-90 GHz (45 m Telescope, 2007, Feb.-Mar.) ★ l -C 5 H , l -C 6 H , l -C 6 H 2, HC 7 N, @ 18-20 GHz (GBT, 2006, Dec.) HC 9 N Long Carbon-Chains ! ★ C 6 H - , C 4 H - Negative Ions !

Detection of Very High Excitation Lines ★ HC 5 N preliminary ( J = 32 – 31, E u = 67 K, J = 33 － 32, E u = 71 K, J = 40 － 39, E u = 104 K) Very High Excitation Lines ! ( T rot ~ 26 ± 12 K) @ 85-106 GHz, IRAM 30 m Carbon-chain molecules exist in warm and dense part of the star forming region !! (N. Sakai et al. 2008)

Origin of Rich Carbon-Chains in L1527 cf NGC1333IRAS4B Star-formation IRAS16293 － 2422 ～ 10 6 yr Carbon-chain molecules are deficient. Starless core Fast collapse L1527 (close to free fall case) ① Some carbon-chain molecules ～ 10 5 yr could survive even after onset of star formation ② Carbon-chains are regenerated by evaporation of methane(CH 4 ) Warm Carbon-Chain Chemistry CH 4 + C + → C 2 H 3 + + H (WCCC) + + e → C 2 H + H + H → ･･･ C 2 H 3 (Sakai et al. 2008; Aikawa et al. 2008).

Search for the Second WCCC Source C 4 H Survey with NRO 45 m

IRAS15398-3359 in Lupus 1 Tachihara et al. 1996 30’ B Hara et al. 1999 A

IRAS15398-3359 in Lupus ★ Various carbon- chains are abundant ! ★ Strong high excitation lines ! HC 5 N ( J =32-31, E u =67 K) + (4 04 -3 03 ) HCO 2

Chemical Variation of Low-Mass SFRs C 4 H 2 (10 1, 9 － 9 1, 8 ) ★ Hot corino chemistry ex; IRAS16293–2422 NGC1333 IRAS4A/4B Carbon-chains are deficient ! ★ Warm carbon-chain chemistry L1527, IRAS15398-3359 Abundant Carbon-chains ! Difference in physical processes of star formation

Scenario CO CO Abundant COMs Slow collapse H H (HCOOCH 3 , (CH 3 ) 2 O, etc.) C depleted as CO CO CH 3 OH CH 3 OH CO H H CO CH 4 H CO CH 3 OH C (ex. IRAS16293-2422 and NGC1333IRAS4A/4B) C CO Abundant Carbon-Chains Fast collapse H C （ ~ free fall timescale ） C H CH 4 CO depleted as C CH 4 C H H H CH 3 OH CH 4 C C (ex. L1527 and IRAS15398-3359)

How is chemical evolution after the Class 0 stage? Minor species!! Key: Major species does not show any variation ! Sensitive line survey is necessary !!

Line Survey of Protostellar Disks with ALMA • Purpose (1) Exploring chemical evolution from protostellar disks to protoplanetary disks (2) Providing new observation tools to study star and planet formation • Targets Class 0, Class I and Class II sources 10 Objects in total.

Line Survey with Interferometer: Powerful Tool for Chemical Analysis Envelope Disk Class 0 Class I Class II (1) Resolve an envelope and a disk (2) Study chemical evolution of an envelope and a disk (3) Study chemical interaction between an envelope and a disk (4) Explore possible source-to-source variation of chemical evolution

Molecules in IRAS16293-2422 with SMA Kuan et al. (2004)

Target Sources (1) • Class 0 Sources Hot Corino Sources IRAS16293-2422 WCCC Sources IRAS15398-3359, L1527 Intermediate Sources L483, B1, IRAS13036-7644 Line Survey with NRO 45 m (ALMA sub-working group activity) L1527 ( L1157) Many Unexpected Lines Some Unidentified Lines

Target Sources (2) • Class I and Class II Sources Need to search for candidate sources by observing minor molecules with existing telescopes (NRO 45 m, ASTE, etc) prior to ALMA observations! Possible chemical variation? (c.f. Hot Corino and WCCC) A few sources in each class will be surveyed. (Survey will start from Class 0 sources…)

Observing Frequencies Detection of Larger B: rotational constant Species Is Equivalent to ν： transition frequency Detection of High Excitation Eu: upper state energy Lines! ν =2B(J+1) ～ 2BJ Eu=BJ(J+1) ～ BJ 2 ～ ν ( ν /4B) Molecular size B/GHz Eu/K (@300 GHz) Eu/K (@100 GHz) C2 40 30 4 C3 10 105 13 C4 5 210 25 C5 3 350 42 C6 1.5 750 83 Importance of Band 3, 4, and 6. Supplementary use of Band 7

Observing Strategy • Frequency Range --- Full Survey! Band 3 84-116 GHz 0.8 GHz x 40 settings Band 4 125-169 GHz 1.2 GHz x 36 settings Band 6 211-275 GHz 1.8 GHz x 36 settings Band 7 275-373 GHz 2.8 GHz x 35 settings Total 147 settings • Assumptions Velocity resolution 0.3 km/s Backend 8192 channels

ALMA Sensitivity • Sensitivity calculation with ETC Freq. Main Array 7m Array TP 100 GHz 808 mK 24 mK 7 mK 150 GHz 382 mK 26 mK 7 mK 230 GHz 215 mK 33 mK 9 mK 350 GHz 154 mK 54 mK 14 mK • Assumptions Spatial resolution 1” Velocity resolution 0.3 km/s Integration time 600 s = 10 min

Time Estimate • Use Main Array with ACA and TP 147 settings x 10 min = 1470 min 10 sources x 1470 min = 14700 min 4 Class 0 sources 3 Class I sources 3 Class II sources Overheads 20% � 18000 min (300 hrs) ACA and TP are necessary to recover extended components!!

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

Collaborators • Dr. Nami Sakai (Univ. of Tokyo) • Mika Sugimura (Univ. of Tokyo) • Osamu Saruwatari (Univ. of Tokyo) • Dr. Takeshi Sakai (NAOJ) • Dr. Tomoya Hirota (NAOJ) • Dr. Shuro Takano (NAOJ) • NRO 45 m Line Survey Group Members

2 nd Tokyo-NRO Workshop Chemical Diagnostics of Star Formation March 5 and 6, 2009 Hongo-Campus, The University of Tokyo Overseas Invited Speakers: Jes Jorgensen (U. Bonn) Suzanne Bisshop (MPI, Bonn) Henrik Beuther (MPI, Heidelberg) Yancy Shirley (U. Arizona) Sheng-Yuan Liu (ASIAA)