Star formation in Perseus: II. SEDs, classification and lifetimes

Working with the submillimetre continuum map of the Perseus molecular cloud (Hatchell et al. 2005), we aimed to determine the evolutionary stage of each submm core in Perseus, and investigate the lifetimes of these phases. We compile spectral energy distributions (SEDs) from 2MASS, Spitzer IRAC, Michelle, IRAS, SCUBA and Bolocam data. Sources are classified starless/protostellar on the basis of infrared and/or outflow detections and Class I/Class 0 on the basis of Tbol, Lbol/Lsmm and F_{3.6}/F_{850}. In order to investigate the dependence of these evolutionary indicators on mass, we construct radiative transfer models of Class 0 sources. Of the submm cores, 56/103 (54%) are confirmed protostars on the basis of infrared emission or molecular outflows. Of these, 22 are classified Class 1 on the basis of three evolutionary indicators, 34 are Class 0, and the remaining 47 are assumed starless. Perseus contains a much greater fraction of Class 0 sources than either Taurus or Rho Oph. Comparing the protostellar with the T Tauri population, the lifetime of the protostellar phase in Perseus is 0.25-0.67 Myr (95% confidence limits). The relative lifetime of the Class 0 and Class 1 phases are similar. We find that for the same source geometry but different masses, evolutionary indicators such as Tbol vary their value. It is therefore not always appropriate to use a fixed threshold to separate Class 0 and Class I sources. More modelling is required to determine the observational characteristics of the Class 0/Class I boundary over a range of masses.

[1]  D. Johnstone,et al.  Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared Surveys , 2006, astro-ph/0610381.

[2]  L. Hillenbrand,et al.  A Distributed Population of Low-Mass Pre-Main-Sequence Stars near the Taurus Molecular Clouds , 2006, astro-ph/0609048.

[3]  J. Bally,et al.  Multiple Outflows and Protostars near IC 348 and the Flying Ghost Nebula , 2006 .

[4]  A. Sargent,et al.  The Evolution of Outflow-Envelope Interactions in Low-Mass Protostars , 2006, astro-ph/0605139.

[5]  D. Padgett,et al.  The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. III. Perseus Observed with IRAC , 2006, astro-ph/0603547.

[6]  D. Johnstone,et al.  The Large- and Small-Scale Structures of Dust in the Star-forming Perseus Molecular Cloud , 2006, astro-ph/0602089.

[7]  M. Ressler,et al.  A Mid-Infrared Study of the Class 0 Cluster in LDN 1448 , 2005, astro-ph/0512541.

[8]  Three-dimensional Models of Embedded High-Mass Stars: Effects of a Clumpy Circumstellar Medium , 2005, astro-ph/0509073.

[9]  Qizhou Zhang,et al.  SiO J = 5-4 in the HH 211 Protostellar Jet Imaged with the Submillimeter Array , 2005, astro-ph/0512252.

[10]  P. Mauskopf,et al.  Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus , 2005, astro-ph/0602259.

[11]  J. Bally,et al.  Multiple Outflows and Protostars in Barnard 1 , 2005 .

[12]  E. F. Ladd,et al.  Star formation in Perseus - Clusters, filaments and the conditions for star formation , 2005 .

[13]  U. Sheffield,et al.  Can variability account for apparent age spreads in OB association colour-magnitude diagrams? , 2005, astro-ph/0508487.

[14]  G. Fuller,et al.  Star formation in Perseus - Clusters, filaments and the conditions for star formation , 2005, astro-ph/0505444.

[15]  A. Whitworth,et al.  How to identify the youngest protostars , 2005, astro-ph/0505291.

[16]  D. Froebrich.  Which Are the Youngest Protostars? Determining Properties of Confirmed and Candidate Class 0 Sources by Broadband Photometry , 2004, astro-ph/0410044.

[17]  K. Tassis,et al.  Ambipolar-Diffusion Timescale, Star Formation Timescale, and the Ages of Molecular Clouds: Is There a Discrepancy? , 2004, astro-ph/0409089.

[18]  R. B. Barreiro,et al.  The very bright SCUBA galaxy count: looking for SCUBA galaxies with the Mexican hat wavelet , 2004, astro-ph/0405156.

[19]  A. A. Kaas,et al.  The young stellar population in the Serpens Cloud Core: An ISOCAM survey ⋆ ⋆⋆ , 2004, astro-ph/0404439.

[20]  T. Harries,et al.  Synthetic infrared images and spectral energy distributions of a young low-mass stellar cluster , 2004, astro-ph/0403582.

[21]  R. Klessen,et al.  Protostellar mass accretion rates from gravoturbulent fragmentation , 2004, astro-ph/0402433.

[22]  J. Monnier,et al.  Three-dimensional dust radiative-transfer models: the Pinwheel Nebula of WR 104 , 2004, astro-ph/0401574.

[23]  M. Meyer,et al.  Low-Mass Stars and Substellar Objects in the NGC 1333 Molecular Cloud , 2003, astro-ph/0312357.

[24]  K. Wood,et al.  Two-dimensional Radiative Transfer in Protostellar Envelopes. II. An Evolutionary Sequence , 2003, astro-ph/0309007.

[25]  M. Mccaughrean,et al.  Molecular Outflows in the Young Open Cluster IC 348 , 2003, astro-ph/0306067.

[26]  E. al.,et al.  From molecular cores to planet-forming disks: An SIRTF legacy program , 2003, astro-ph/0305127.

[27]  G. Rieke,et al.  A Census of the Young Cluster IC 348 , 2003, astro-ph/0304409.

[28]  C. Aspin.  THE EVOLUTIONARY STATE OF STARS IN THE NGC 1333S STAR FORMATION REGION , 2003 .

[29]  T. Magakian.  Merged catalogue of reflection nebulae , 2003 .

[30]  S. N. Raines,et al.  A Study of the Luminosity and Mass Functions of the Young IC 348 Cluster Using FLAMINGOS Wide-Field Near-Infrared Images , 2003, The Astronomical Journal.

[31]  Volker Bromm,et al.  The formation of a star cluster: predicting the properties of stars and brown dwarfs , 2002, astro-ph/0212380.

[32]  L. Hartmann,et al.  The Initial Mass Function in the Taurus Star-forming Region , 2002 .

[33]  J. Richer,et al.  Completion of a SCUBA Survey of Lynds Dark Clouds and Implications for Low-mass Star Formation , 2002, astro-ph/0209082.

[34]  N. Evans,et al.  Lensing Properties of Cored Galaxy Models , 2002, astro-ph/0204206.

[35]  J. Alves,et al.  The Origins of Stars and Planets: The VLT View: Proceedings of the ESO Workshop Held in Garching, Germany, 24–27 April 2001 , 2002 .

[36]  N. Santos,et al.  The Origins of Stars and Planets: The VLT View , 2002 .

[37]  P. Hartigan,et al.  Proper Motions of the HH 47 Jet Observed with the Hubble Space Telescope , 2001, astro-ph/0507526.

[38]  T. Preibisch,et al.  Deep Chandra X-Ray Observatory Imaging Study of the Very Young Stellar Cluster IC 348 , 2001 .

[39]  C. Clarke,et al.  Competitive accretion in embedded stellar clusters , 2001, astro-ph/0102074.

[40]  L. Hartmann,et al.  On Age Spreads in Star-forming Regions , 2001 .

[41]  A. Whitworth,et al.  An Empirical Model for Protostellar Collapse , 2000, astro-ph/0009325.

[42]  Frédérique Motte,et al.  The circumstellar environment of low-mass protostars: A millimeter continuum mapping survey ? , 2001 .

[43]  Christine D. Wilson,et al.  Large-Area Mapping at 850 Microns. I. Optimum Image Reconstruction from Chop Measurements , 2000 .

[44]  G. Anglada,et al.  Discovery of a Subarcsecond Radio Binary Associated with the SVS 13 Star in the HH 7-11 Region , 2000 .

[45]  J. Carpenter.  2MASS Observations of the Perseus, Orion A, Orion B, and Monoceros R2 Molecular Clouds , 2000, astro-ph/0009118.

[46]  T. Harries.  Synthetic line profiles of rotationally distorted hot-star winds , 2000 .

[47]  L. Mundy,et al.  Tracing the Mass during Low-Mass Star Formation. II. Modeling the Submillimeter Emission from Preprotostellar Cores , 2000, astro-ph/0006183.

[48]  J. O'Linger,et al.  Giant Molecular Outflows Powered by Protostars in L1448 , 2000, astro-ph/0005317.

[49]  Lee G. Mundy,et al.  Unveiling the Circumstellar Envelope and Disk: A Subarcsecond Survey of Circumstellar Structures , 1999, astro-ph/9908301.

[50]  D. Ward-Thompson,et al.  A far-infrared survey of molecular cloud cores , 1999, astro-ph/9908230.

[51]  G. Sandell,et al.  NGC 1333—Protostars, Dust Shells, and Triggered Star Formation , 2000 .

[52]  G. Anglada,et al.  The Nature of the Radio Continuum Sources Embedded in the HH 7-11 Region and Its Surroundings , 1999 .

[53]  J. Richer,et al.  The Structure of Protostellar Envelopes Derived from Submillimeter Continuum Images , 1999, astro-ph/9909494.

[54]  G. Rieke,et al.  Low-Mass Star Formation and the Initial Mass Function in the ρ Ophiuchi Cloud Core , 1999, astro-ph/9905286.

[55]  D. Ward-Thompson,et al.  L1448 IRS 2: A HIRES-identified Class 0 Protostar , 1999 .

[56]  P. Myers,et al.  A Catalog of Optically Selected Cores , 1999, astro-ph/9901175.

[57]  W. Dent,et al.  The submillimetre colour of young stellar objects , 1998 .

[58]  P. Andre',et al.  Protostars in Perseus: Outflow-induced Fragmentation , 1998 .

[59]  C. Lada,et al.  Low-Mass Star Formation and the Initial Mass Function in IC 348 , 1998 .

[60]  P. T. de Zeeuw,et al.  A Hipparcos Census of the Nearby OB Associations , 1998, astro-ph/9809227.

[61]  G. Anglada,et al.  Is SVS 13 the Exciting Source of the HH 7-11 Flow? , 1997 .

[62]  J. Bohigas,et al.  IRAS Sources Associated With Small Nebulae in Star Forming Regions: Optical and Near Infrared Images , 1997 .

[63]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[64]  J. Alves,et al.  Near-Infrared Imaging of Embedded Clusters: NGC 1333 , 1996 .

[65]  R. Hurt,et al.  A Cluster of Class 0 Protostars in Serpens: An IRAS HIRES Study , 1996 .

[66]  L. Hartmann,et al.  Pre-Main-Sequence Evolution in the Taurus-Auriga Molecular Cloud , 1995 .

[67]  John E. Carlstrom,et al.  NGC 1333 IRAS 4: Further Multiplicity Revealed with the CSO-JCMT Interferometer , 1995 .

[68]  P. Myers,et al.  Bolometric temperature and young stars in the Taurus and Ophiuchus complexes , 1995 .

[69]  M. Mccaughrean,et al.  Discovery of a Molecular Hydrogen Jet near IC 348 , 1994 .

[70]  E. Young,et al.  Further Mid-Infrared Study of the rho Ophiuchi Cloud Young Stellar Population: Luminosities and Masses of Pre--Main-Sequence Stars , 1994 .

[71]  A. Goodman,et al.  Dense cores in dark clouds. 10: Ammonia emission in the Perseus molecular cloud complex , 1994 .

[72]  Leo Blitz,et al.  DETERMINING STRUCTURE IN MOLECULAR CLOUDS , 1994 .

[73]  P. Andre',et al.  A submillimetre continuum survey of pre-protostellar cores , 1994 .

[74]  P. Andre',et al.  From T Tauri stars to protostars: Circumstellar material and young stellar objects in the rho Ophiuchi cloud , 1994 .

[75]  S. Malhotra,et al.  On graphite and the 2175 Å extinction profile , 1993 .

[76]  P. Myers,et al.  Bolometric temperatures of young stellar objects , 1993 .

[77]  P. Andre',et al.  Submillimeter Continuum Observations of rho Ophiuchi A: The Candidate Protostar VLA 1623 and Prestellar Clumps , 1993 .

[78]  J. Moran,et al.  The Exciting Source of the Bipolar Outflow in L1448 , 1990 .

[79]  L. Hartmann,et al.  An IRAS Survey of the Taurus-Auriga Molecular Cloud , 1990 .

[80]  E. Young,et al.  IRAS Observations of the Rho Ophiuchi Infrared Cluster: Spectral Energy Distributions and Luminosity Function , 1989 .

[81]  R. E. Jennings,et al.  IRAS observations of NGC 1333 , 1987 .

[82]  J. Bally,et al.  Compact Radio Sources Associated with Molecular Outflows , 1986 .

[83]  J. Brand,et al.  Photometric Age Determination of OB-Associations , 1985 .

[84]  W. Boland,et al.  Birth and evolution of massive stars and stellar groups; Proceedings of the Symposium, Dwingeloo, Netherlands, September 24-26, 1984 , 1985 .

[85]  H. M. Lee,et al.  Optical properties of interstellar graphite and silicate grains , 1984 .

[86]  K. Nordsieck,et al.  The Size distribution of interstellar grains , 1977 .

[87]  R. Ulrich.  An infall model for the T Tauri phenomenon , 1976 .

[88]  F. Vrba,et al.  Infrared surveys of dark-cloud complexes. II. The NGC 1333 region. , 1976 .