Presentation on theme: "Herschel Observations of Extraordinary Sources (HEXOS) J. L. Neill, E. A. Bergin, N. R. Crockett, Department of Astronomy, University of Michigan, 830."— Presentation transcript:
Herschel Observations of Extraordinary Sources (HEXOS) J. L. Neill, E. A. Bergin, N. R. Crockett, Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church St., Ann Arbor, MI 48109 and the HEXOS team http://www.hexos.org/team.php 1 Orion KL + Sgr B2(N) teams: Dariusz Lis, Peter Schilke, Raquel Monje, Jo-Hsin Chen, Dana Anderson, Brett McGuire, Tatiana Vasyunina, Shanshan Yu, Martin Emprechtinger, Shiya Wang, Tom Bell, Geoffrey Blake, John Pearson, Rene Plume, Brent Harris, Amanda Steber, Sheng-Li Qin, Cecile Favre, Steven Lord, Andrew Burkhardt, Trevor McNeill
2 Overview: Herschel Space Observatory Launched May 14, 2009 Lissajous orbit around L2 Estimated mission end February/March 2013 Total wavelength range: 672-55 m (450-5500 GHz) Three instruments onboard: Heterodyne Instrument for the Far Infrared (HIFI) high-resolution (< 1 MHz) spectrometer, 480-1280, 1410-1900 GHz Spectral and Photometric Imaging Receiver (SPIRE) imaging photometer + imaging FT spectrometer, 671-194 m Photodetector Array Camera and Spectrometer (PACS) imaging camera + medium-resolution spectrometer, 210-55 m
3 HEXOS Key Program PI: E. Bergin, University of Michigan Unbiased full-bandwidth HIFI surveys of 5 sources within the Orion and Sagittarius B2 molecular clouds (Orion KL, Orion S, Orion Bar, Sgr B2(M), Sgr B2(N)) Some goals of these surveys: characterize the sub-mm spectrum of dense, warm molecular gas; provide a near-complete chemical assay of star-forming gas in a variety of environments; use high-excitation transitions to probe the chemical/physical state of gas in close proximity to new stars; catalog U-lines; new molecular detections? Bergin et al. 2010, A&A, 521, L20
4 Fullband Analysis Methodology (Orion KL and Sgr B2(N)) LTE modeling—XCLASS/MAGIX Divide the labor among ~20 people, each with one/a few molecules assigned; consistent tools (virtual machine); several iterations as blends are more accurately accounted for Derive physical parameters for each spectral component: source size (also using interferometry), rotation temperature, column density Orion KL analysis complete, manuscript in prep (N. Crockett et al.); Sgr B2(N) in progress Orion KL fullband spectrum
7 Modeled Molecules (Orion KL) CO ( 13 CO, C 18 O, C 17 O) NO NS SO ( 34 SO, 33 SO, S 18 O) SiO SiS H 35 Cl, H 37 Cl CN CS (C 34 S, C 33 S, 13 CS) CCH H 2 O (H 2 18 O, H 2 17 O, HDO, HD 18 O, D 2 O) H 2 S (H 2 34 S, H 2 33 S) HCO + HCS + N 2 H + SO 2 ( 34 SO 2, 33 SO 2 ) NH 3 ( 15 NH 3, NH 2 D) HCN (H 13 CN, HC 15 N, DCN) HNC (HN 13 C, H 15 NC) OCS H 2 CO (H 2 13 CO, HDCO) H 2 CS HNCO (HN 13 CO) H 2 CCO HC 3 N CH 3 OH ( 13 CH 3 OH, CH 2 DOH, CH 3 OD) CH 3 CN ( 13 CH 3 CN, CH 3 13 CN) NH 2 CHO CH 3 CH 2 OH CH 3 OCH 3 HCOOCH 3 CH 3 CH 2 CN Others in Sgr B2(N) (and line-of-sight) CH, CH + NH, NH 2 H 3 O + HF, H 2 Cl + CH 2 NH, CH 3 NH 2, HOCO +
8 Modeling weak lines can be done with high fidelity (many lines observed per molecule) Methanol in Sgr B2(N) 2-component LTE model: (1)170 K, 3.5”, 4.0 x 10 18 cm -2 (2)60 K, 10”, 6.0 x 10 16 cm -2 J.L. Neill et al., submitted.
14 Complex organics: massive number of transitions per molecule -strong constraints on physical parameters -temperature gradients (CH 3 OH, CH 3 CN, CH 3 CH 2 CN) -including tracers of gas nearest embedded protostar(s) Fraction of molecular emission arising from states with various upper-state energies: Which molecules are tracing the hottest gas in the source? E upper :
17 Summary High-resolution surveys of the two most important sources for high-mass star formation, molecular identifications in a largely unexplored frequency region Working on full-band analysis of all known molecules in these spectra Prototype for working with massive data sets Fully deconvolved spectra, along with best-fit LTE models will be released -further investigations with known molecules -U-line identifications (vib. excited species, isotopes, new molecules…) Acknowledgements: Funding: NASA (JPL/Caltech) Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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