Star Formation Legacy Project: Status and Results Shun Ishii (NAOJ/JAO) Fumitaka Nakamura(NAOJ) Kong et. al.,2018
Project members and collaborators NAOJ - Fumitaka Nakamura(PI), Ryohei Kawabe, Chihomi Hara, Takashi Tsukagoshi, Shun Ishii, Shuri Oyamada (Japan Women Univ.), Takayoshi Kusune (PD), Hideaki Takemura(M1) Tokyo Gakugei University - Tomomi Shimoikura, Asha Hirose, Kazuhito Dobashi Ibaraki Univ. - Yoshihiro Tanabe (D3), Munetake Momose Niigata Univ. - Umiko Urasawa, Kazushige Sasaki, Ryoichi Nishi National Thing Hua Univ. - Shih-Ping Lai, Sheng-Jun Lin, Vivien Chen Others - Koji Sugitani (Nagoya City Univ.), Sachiko Okumura (Japan Women Univ.), Yoshimi Kitamura (JAXA), Yoshito Shimajiri (CEA/Sacley), Quang Nguyen Luong (KASI), Patricio Sanhueza (NAOJ) International Collaborators - John Carpenter (JAO), Hector Arce (Yale), Shuo Kong (PD, Yale), Jonathan Tan (Florida), Wanggi Lim (D3, Florida), Peter Schlike, Sümeyye Suri (D3,Cologne), Paul Goldsmith, Peregrine McGehe (Caltech), Jens Kauffman, Thusuhara Pillai (MPI), John Bally (Colorado), Ralf Klessen, Rowan Smith (Heidelberg), Paolo Padoan (Barcelona), Alyssa Goodman (CfA), Andrea Isella (Rice), Doug Johnstone (HEA, Canada) et al. + CARMA consortium, Alvaro Hacar (Leiden), Zhi-Yun Li (Virginia)
Outline ✴ Motivation and Science goals ✴ Project overview ✴ Observations ✴ Result from Orion A Observations ✴ Summary
Why is star formation so inefficient? ✴ Star formation may be suppressed by turbulence, magnetic field, and stellar feedback. ✴ Towards a full understanding of the roles of these processes in star formation, we characterize the cloud structure and dynamics by wide-field mapping observations with multiple lines. ✴ Wide-field mapping observations are important to understand the effects of stellar feedback and external events like large-scale shocks because they potentially affect cloud properties and structures in a cloud scale, 1 − 10 pc ✴ 12 CO, 13 CO, C 18 O, N 2 H + observations cover the density range from 10 2 cm − 3 to 10 5 cm − 3 . ✴ Maps of nearby clouds by NRO 45m telescope can be directly compared with the maps of the molecular clouds within a few kpc by ALMA in a comparable spatial resolution of a few thousand au.
NRO 45 m Star Formation Legacy Project ✴ Using the new receiver FOREST, we carried out wide-field mapping observations toward nearby star forming regions in 12 CO (1-0), 13 CO (1-0), C 18 O (1-0), N 2 H + (1-0), covering the density range of 100 to 10 5 cm -3 . ✴ http://th.nao.ac.jp/MEMBER/nakamrfm/sflegacy/sflegacy.html ✴ three year project: 400 hours x 3 years ~ 1200 hours ✴ Targets ✴ Orion A (400 pc): 2-3 square degree ✴ Aquila Rift (415 pc): 1 square degree ✴ M17 (2000 pc): 1 square degree 10 pc Orion A M17 Aquila Rift Povich et al., 2010
Orion A 12 CO 13 CO C 18 O N 2 H + H 2 Column density
Aquila Rift 12 CO 13 CO C 18 O N 2 H + CCS Spitzer W40 Serpens South
M17 N 2 H + 12 CO 13 CO Spitzer C 18 O
see Takemura-san’s poster + CMF in Orion A: Publication Plan Initial Results will be presented mainly in the PASJ special issue (March, 2019) 1. Nobeyama Mapping Observations toward Nearby Molecular Clouds, Orion A, Aquila Rift, and M17, Nakamura et al., submitted 2. Nobeyama Mapping Observations toward Orion A. I. A New Method of Molecular Outflow Search, Tanabe et al., submitted 3. Nobeyama Mapping Observations toward Orion A. II. Classification of Cloud Structures and Variation of the 13 CO/C 18 O Abundance Ratio due to far-UV Radiation, Ishii et al., submitted 4. Nobeyama Mapping Observations toward Orion A. III. Initial Results of NH + Core Survey, Nakamura et al., accepted 5. Nobeyama Mapping Observations toward Orion A. IV. Multi-Line Observations toward an Outflow-shocked Region, OMC-2, FIR 3/4/5, in prep. 6. Nobeyama Mapping Observations toward Aquila Rift. I. Cloud Structure, Shimoikura et al. (2019) 7. Nobeyama Mapping Observations toward Aquila Rift. II. Effect of the W40 HII region, Shimoikura et al. (2019) 8. Nobeyama Mapping Observations toward Aquila Rift. III. Relationship between Magnetic Field and Cloud Structure, Kusune et al. (2019) 9. Nobeyama Mapping Observations toward M17. I. Cloud Structure, Dobashi et al. in prep. 10. Nobeyama Mapping Observations toward M17. I. N2H+ Clump Survey, Hirose et al. in prep. 11. Nobeyama Mapping Observations toward M17. II. Relationship between Magnetic Field and Cloud Structure, Sugitani et al. (2019) Other papers (Orion A, CARMA+45m) (a) The CARMA Orion Survey, Kong et al. (2018) (b) Expanding Carbon Monoxide Shells in the Orion A Molecular Cloud, Feddersen et al. (2018) (c) Star Formation in the Orion A Molecular Cloud I. Properties of Filaments as Seen in 13 CO (1-0) and C 18 O (1-0) Emission, Suri et al. (2018) ………
CARMA-NRO Orion maps ~20” ~5” ~5” Final combined map is more than 3 times of this image.
CARMA-NRO Orion maps 12 CO( J =1-0) red: 9.8 - 12.1 km/s blue: 7.3 - 9.6 km/s green: 4.8 - 7.1 km/s Kong et al. (2018) 12 CO( J =1-0)
A result from Orion Observations Classification of Cloud Structures and Variation of the 13 CO/C 18 O Abundance Ratio due to far-UV Radiation
Cloud identification using 13 CO data 13 CO Column density ✴ 13 CO( J =1-0) is a good tracer to internal structures through entire molecular clouds ✴ 12 CO( J =1-0): optically thick, Tex ✴ C 18 O( J =1-0): traces dense gas ✴ We use the columns density cube fo 13 CO to analyze cloud structures C 18 O Column density
Identification of Cloud Structures by SCIMES Analysis: ✴ Cloud identification by SCIMES (Colombo et al.,2015) Result ✴ 78 clouds identified ✴ Well-known subregions are naturally identified as independent structures ✴ Diffuse clouds outsides of the integral shaped filament are also detected ✴ Small clouds appear to overlap with larger clouds.
Identification of Cloud Structures by SCIMES OMC-2/3 Analysis: ✴ Cloud identification by SCIMES (Colombo et al.,2015) OMC-1 DLSF OMC-4 OMC-5 Result ✴ 78 clouds identified ✴ Well-known subregions are naturally identified as independent structures L1641N ✴ Diffuse clouds outsides of the integral shaped filament are also detected ✴ Small clouds appear to overlap with larger clouds.
Identification of Cloud Structures by SCIMES Group1: Clouds in the integrate-shaped filament(ISF) Group2: Clouds in south and east/west side of ISF Group3: DLSF and diffuse clouds
Identification of Cloud Structures by SCIMES Group1: Clouds in the integrate-shaped filament(ISF) Group2: Clouds in south and east/west side of ISF Group3: DLSF and diffuse clouds These clouds are isolated from others in the dendrogram
Identification of Cloud Structures by SCIMES Group1: Clouds in the integrate-shaped filament(ISF) Group2: Clouds in south and east/west side of ISF Group3: DLSF and diffuse clouds These clouds are isolated from others in the dendrogram → interacting with HII regions
Environmental effect on the abundance ratio The abundance ratio between 13 CO and C 18 O has significant variation over Orion A X ( 13CO)/ X ( C18O) Shimajiri et al., 2014 Selective dissociation of C 18 O on the edge on PDR? - The FUV emission selectively dissociates CO isotopes - C 18 O molecules are expected to be selectively dissociated by UV photons. (Lada et al. 1994, Shimajiri et al. 2014)
Environmental effect on the abundance ratio The abundance ratio between 13 CO and C 18 O has significant variation over Orion A → large variation by clouds and within a cloud especially on edges → the ratio changes along the velocity axis Position-velocity diagram X ( 13CO)/ X ( C18O) of X ( 13CO)/ X ( C18O)
Environmental effect on the abundance ratio The abundance ratio between 13 CO and C 18 O has significant variation over Orion A → large variation by clouds and within a cloud → the ratio changes along the velocity axis → we compare with the dust extinction and FUV field derived by Herschel data X ( 13CO)/ X ( C18O) Dust extinction A V FUV field intensity G 0
X( 13 CO)/C 18 O - Av by clouds h i g h X ( 13 C O ) / C 18 O low X( 13 CO)/C 18 O ✴ High ratio clouds: ✴ the abundance ratio decreases with N( 13 CO) and Av ✴ Clouds are irradiated by strong FUV ✴ Low ratio clouds: ✴ the abundance ratio is almost independent ✴ FUV field is (relatively) low
X( 13 CO)/C 18 O - FUV by clouds G 0 N( 13 CO) or Av ✴ Selective dissociation of C 18 O is enhanced on the surface of clouds that are irradiated by FUV and it is suppressed under low FUV environment.
Cloud Structures in Orion A: Summary ✴ 78 molecular clouds are identified by SCIMES. ✴ Well-known internal clouds are naturally identified as independent structures in Orion A. ✴ Isolated structures in the dendrogram are likely to be produced by interaction with HII regions. ✴ A large deviation of the abundance ratio X ( 13 CO)/ X ( C 18 O) is found among identified clouds in the position-position-velocity space. ✴ The results support that selective dissociation of C 18 O on the surfaces of clouds irradiated by FUV.
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