L1599B: CLOUD ENVELOPE AND C+ EMISSION IN A REGION OF MODERATELY ENHANCED RADIATION FIELD

We study the effects of an asymmetric radiation field on the properties of a molecular cloud envelope. We employ observations of carbon monoxide (12CO and 13CO), atomic carbon, ionized carbon, and atomic hydrogen to analyze the chemical and physical properties of the core and envelope of L1599B, a molecular cloud forming a portion of the ring at ≃27 pc from the star Λ Ori. The O8 star provides an asymmetric radiation field that produces a moderate enhancement of the external radiation field. Observations of the [C ii] fine structure line with the GREAT instrument on SOFIA indicate a significant enhanced emission on the side of the cloud facing the star, while the [C i], 12CO and 13CO J = 1–0 and 2–1, and 12CO J = 3–2 data from the Purple Mountain Observatory and APEX telescopes suggest a relatively typical cloud interior. The atomic, ionic, and molecular line centroid velocities track each other very closely, and indicate that the cloud may be undergoing differential radial motion. The H i data from the Arecibo GALFA survey and the SOFIA/GREAT [C ii] data do not suggest any systematic motion of the halo gas, relative to the dense central portion of the cloud traced by 12CO and 13CO.

[1]  M. Juvela,et al.  PLANCK COLD CLUMPS IN THE λ ORIONIS COMPLEX. I. DISCOVERY OF AN EXTREMELY YOUNG CLASS 0 PROTOSTELLAR OBJECT AND A PROTO-BROWN DWARF CANDIDATE IN THE BRIGHT-RIMMED CLUMP PGCC G192.32–11.88 , 2015, 1511.09121.

[2]  P. Goldsmith,et al.  HERSCHEL GALACTIC PLANE SURVEY OF [N ii] FINE STRUCTURE EMISSION , 2015, 1510.05706.

[3]  H. Müller,et al.  VELOCITY-RESOLVED [C ii] EMISSION AND [C ii]/FIR MAPPING ALONG ORION WITH HERSCHEL , 2015, The Astrophysical journal.

[4]  P. Goldsmith,et al.  PHOTON-DOMINATED REGION MODELING OF THE [C i], [C ii], AND CO LINE EMISSION FROM A BOUNDARY IN THE TAURUS MOLECULAR CLOUD , 2014, 1409.1210.

[5]  Y. Sekimoto,et al.  FLASH$^{+}$ —A Dual-Channel Wide-Band Spectrometer for APEX , 2014, IEEE Transactions on Terahertz Science and Technology.

[6]  H. Rix,et al.  A LARGE CATALOG OF ACCURATE DISTANCES TO MOLECULAR CLOUDS FROM PS1 PHOTOMETRY , 2014, 1403.3393.

[7]  P. Goldsmith,et al.  C+ IN THE INTERSTELLAR MEDIUM: COLLISIONAL EXCITATION BY H2 REVISITED , 2013, 1312.0282.

[8]  P. Goldsmith.  DIFFUSE MOLECULAR CLOUD DENSITIES FROM UV MEASUREMENTS OF CO ABSORPTION , 2013, 1307.8374.

[9]  P. Goldsmith,et al.  A Herschel [C ii] Galactic plane survey - I. The global distribution of ISM gas components , 2013, 1304.7770.

[10]  J. Greenberg,et al.  Interstellar Dust and Related Topics , 2012 .

[11]  Sheng Li,et al.  Development of Superconducting Spectroscopic Array Receiver: A Multibeam 2SB SIS Receiver for Millimeter-Wave Radio Astronomy , 2012, IEEE Transactions on Terahertz Science and Technology.

[12]  P. Goldsmith,et al.  COLLISIONAL EXCITATION OF THE [C ii] FINE STRUCTURE TRANSITION IN INTERSTELLAR CLOUDS , 2012, 1209.4536.

[13]  Erin C. Smith,et al.  EARLY SCIENCE WITH SOFIA, THE STRATOSPHERIC OBSERVATORY FOR INFRARED ASTRONOMY , 2012, 1205.0791.

[14]  Andreas Bell,et al.  GREAT : early science results Special feature L etter to the E ditor High-resolution wide-band fast Fourier transform spectrometers , 2012 .

[15]  U. U. Graf,et al.  GREAT: the SOFIA high-frequency heterodyne instrument , 2012, 1203.2845.

[16]  Y. Okada,et al.  GREAT/SOFIA atmospheric calibration , 2012, 1203.1661.

[17]  M. Lombardi,et al.  2MASS wide field extinction maps - IV. The Orion, Monoceros R2, Rosette, and Canis Major star forming regions , 2011, 1107.5096.

[18]  D. Byun,et al.  100-GHZ BAND TEST OBSERVATIONS OF THE KVN 21-M RADIO TELESCOPES , 2011 .

[19]  J. Peek,et al.  THE GALFA-Hi SURVEY: DATA RELEASE 1 , 2011, 1101.1879.

[20]  Di Li,et al.  THE RELATION BETWEEN GAS AND DUST IN THE TAURUS MOLECULAR CLOUD , 2010, 1007.5060.

[21]  S. Ott,et al.  Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy , 2010, 1005.5331.

[22]  D. Padgett,et al.  EVIDENCE FOR DUST EVOLUTION WITHIN THE TAURUS COMPLEX FROM SPITZER IMAGES , 2009, 0906.5025.

[23]  Michael Olberg,et al.  A Swedish heterodyne facility instrument for the APEX telescope , 2008 .

[24]  H. Liszt.  Formation, fractionation and excitation of carbon monoxide in diffuse clouds , 2007, 0710.2237.

[25]  J. Black,et al.  A computer program for fast non-LTE analysis of interstellar line spectra With diagnostic plots to interpret observed line intensity ratios , 2007, 0704.0155.

[26]  Catherine J. Cesarsky,et al.  The Atacama Pathfinder EXperiment (APEX) : a new submillimeter facility for southern skies , 2006 .

[27]  J. L. Bourlot,et al.  A Model for Atomic and Molecular Interstellar Gas: The Meudon PDR Code , 2006, astro-ph/0602150.

[28]  C. Kramer,et al.  The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI) , 2005, Infrared and Millimeter Waves, Conference Digest of the 2004 Joint 29th International Conference on 2004 and 12th International Conference on Terahertz Electronics, 2004..

[29]  A. Tielens,et al.  Neutral Atomic Phases of the Interstellar Medium in the Galaxy , 2003 .

[30]  D. Hollenbach,et al.  Time Dependence of the Ultraviolet Radiation Field in the Local Interstellar Medium , 2002, astro-ph/0202196.

[31]  Di Li,et al.  H I Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation , 2002, astro-ph/0206396.

[32]  M. Lombardi,et al.  Mapping the interstellar dust with near-infrared observations: An optimized multi-band technique , 2001, astro-ph/0109135.

[33]  R. Mathieu,et al.  The Spatial Distribution of the λ Orionis Pre-Main-Sequence Population , 2001 .

[34]  Alexander G. G. M. Tielens,et al.  Photodissociation Regions in the Interstellar Medium of Galaxies , 1999 .

[35]  M. Masheder,et al.  CO Observations of the λ-Orionis Ring , 1998, Publications of the Astronomical Society of Australia.

[36]  A. Penzias,et al.  (C-12)/(C-13) isotope ratio in the local interstellar medium from observations of (C-13)(O-18) in molecular clouds , 1993 .

[37]  B. Andersson,et al.  Warm neutral halos around molecular clouds. VI - Physical and chemical modeling , 1993 .

[38]  I. Gatley,et al.  A spectroscopic study of the Dr 21 outflow source. III - The CO line emission , 1991 .

[39]  M. Morris,et al.  An Expanding System of Molecular Clouds Surrounding lambda Orionis , 1987 .

[40]  P. Goldsmith,et al.  A detailed examination of the kinematics of rotating dark clouds , 1986 .

[41]  S. Lichten,et al.  Warm H I Halos around molecular clouds , 1983 .

[42]  C. Lada,et al.  Star formation in the lambda orionis region. I. The distribution of young objects , 1982 .

[43]  P. Murdin,et al.  The Lambda Orionis association , 1977 .

[44]  R. Balian,et al.  Atomic and molecular physics and interstellar matter , 1975 .

[45]  C. M. Wade.  A 21-cm line study of an expanding HIl region. , 1957 .