Protostellar half-life: new methodology and estimates

Abstract

(Abridged) Protostellar systems evolve from prestellar cores, through the deeply embedded stage and then disk-dominated stage, before they end up on the main sequence. Knowing how much time a system spends in each stage is crucial for understanding how stars and associated planetary systems form, because a key constraint is the time available to form such systems. Equally important is understanding what the spread in these time scales is. The most commonly used method for inferring protostellar ages is to assume the lifetime of one evolutionary stage, and then scale this to the relative number of protostars in the other stages, i.e., assuming steady state. This method does not account for the underlying age distribution and apparent stochasticity of star formation, nor that relative populations are not in steady state. To overcome this, we propose a new scheme where the lifetime of each protostellar stage follows a distribution based on the formalism of sequential nuclear decay. The main assumptions are: Class 0 sources follow a straight path to Class III sources, the age distribution follows a binomial distribution, and the star-formation rate is constant. The results are that the half-life of Class 0, Class I, and Flat sources are (2.4+/-0.2)%, (4.4+/-0.3)%, and (4.3+/-0.4)% of the Class II half-life, respectively, which translates to 47+/-4, 88+/-7, and 87+/-8 kyr, respectively, for a Class II half-life of 2 Myr for protostars in the Gould Belt clouds with more than 100 protostars. The mean age of these clouds is 1.2+/-0.1 Myr, and the star formation rate is (8.3+/-0.5)x10^-4 Msun/yr. The critical parameters in arriving at these numbers are the assumed half-life of the Class II stage, and the assumption that the star-formation rate and half-lives are constant. This method presents a first step in moving from steady-state to non-steady-state solutions of protostellar populations.

arXiv commentAccepted for publication in A&A

References in corpus (20)

• Galactic Stellar and Substellar Initial Mass Function
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Properties of the Youngest Protostars in Perseus, Serpens, and Ophiuchus
• Star formation in Perseus - V. Outflows detected by HARP
• Young Stellar Objects in the Gould Belt
• A 0.2 solar mass protostar with a Keplerian disk in the very young L1527 IRS system
• Evolutionary Signatures in the Formation of Low-Mass Protostars. II. Towards Reconciling Models and Observations
• A Herschel and APEX Census of the Reddest Sources in Orion: Searching for the Youngest Protostars
• Evolutionary Signatures in the Formation of Low-Mass Protostars
• The formation of active protoclusters in the Aquila Rift: A millimeter continuum view
• Zoom-Simulations of Protoplanetary Disks starting from GMC scales
• Testing the universality of the star formation efficiency in dense molecular gas
• The nature of the Class I population in Ophiuchus as revealed through gas and dust mapping
• The Herschel Orion Protostar Survey: Luminosity and Envelope Evolution
• Detection of Infall in the Protostar B335 with ALMA
• Low Mass Stars and Substellar Objects in the NGC 1333 Molecular Cloud
• The Gaia-ESO Survey: Dynamical Analysis of the L1688 region in Ophiuchus
• Mass and luminosity evolution of young stellar objects
• Characterizing the Youngest Herschel-detected Protostars II. Molecular Outflows from the Millimeter and the Far-infrared
• An Estimation of the Star Formation Rate in the Perseus Complex

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• Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
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• The Evolution of Protostellar Outflow Cavities, Kinematics, and Angular Distribution of Momentum and Energy in Orion A: Evidence for Dynamical Cores
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• Low Mass Stars as Tracers of Star and Cluster Formation
• Detection of Irregular, Sub-mm Opaque Structures in the Orion Molecular Clouds: Protostars within 10000 years of formation?
• Steady Wind-Blown Cavities within Infalling Rotating Envelopes: Application to the Broad Velocity Component in Young Protostars
• The outbursting protostar 2MASS~22352345+7517076 and its environment
• Which Part of Dense Cores Feeds Material to Protostars?: The Case of L1489 IRS
• CAMPOS II. The onset of protostellar disk substructures and planet formation
• Evolution and Kinematics of Protostellar Envelopes in the Perseus Molecular Cloud
• Physical conditions for dust grain alignment in Class 0 protostellar cores II. The role of the radiation field in models aligning/disrupting dust grains
• Planetesimal formation via the streaming instability in simulations of infall dominated young disks
• The Ages of Optically Bright Sub-Clusters in the Serpens Star-Forming Region
• Spatial Statistics in Star Forming Regions: Is Star Formation Driven By Column Density Alone?
• A census of young stellar objects in two line-of-sight star forming regions toward IRAS 22147+5948 in the outer Galaxy
• Assessing the accuracy of the star formation rate measurements by direct star count in molecular clouds
• Water emission tracing active star formation from the Milky Way to high-$z$ galaxies
• The bound origin of low-mass stellar binaries
• Can Protostellar Outflows Set Stellar Masses?
• Origin of compact exoplanetary systems during disk infall
• The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars VI. Insights from Radiative Transfer Modeling