do protostellar luminosities imply episodic accretion?

Do Protostellar Luminosities Imply Episodic Accretion?

Oort 2014 WorkshopTuesday, May 13, 2014

Mike Dunham, SMA Fellow, CfA

Protostellar Accretion

• m, m_dot not directly observable

• Luminosity is indirect tracer of m_dot

• Constrain accretion theories?

• Small, biased samples; incompletely sampled SEDs

Dunham et al. (2014), credit to W. Fischer

Protostellar Luminosities

Protostellar Luminosities

Dunham et al. (2014), credit to W. Fischer

Protostellar Luminosities

Kenyon et al. (1990, 1994); Kenyon & Hartmann (1995); Dunham et al. (2013)

Protostellar Luminosities

Kenyon et al. (1990, 1994); Kenyon & Hartmann (1995)Dunham et al. (2010a), Young & Evans (2005)

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Protostellar Luminosities

Dunham et al. (2014), credit to W. Fischer

Variable/Episodic Accretion?

Variable/Episodic Accretion: Does It Work?Protostellar Accretion

Variable/Episodic Accretion: Does It Work?

Dunham et al. (2010a)

Protostellar Accretion

Vorobyov & Basu (2005, 2006, 2010)Dunham & Vorobyov (2012)

Protostellar Accretion

Variable/Episodic Accretion: Does It Work?

Protostellar Accretion

Dunham et al. (2014), credit to S. Offner(Dunham & Vorobyov 2012; McKee & Offner (2010); Offner & McKee 2011; Myers 2009-2014)

Mass-dependent accretion can also workRelative importance of stochastic vs. secular processes?

Comments from the skeptic

Episodic Accretion

Does the Variability Matter?

Vorobyov & Basu (2005, 2006, 2010)Dunham & Vorobyov (2012)

Episodic Accretion

Is the IMF Weighting Correct?Are relatively high-mass stars missing?

Vorobyov & Basu (2005, 2006, 2010)Dunham & Vorobyov (2012)

Episodic Accretion

Are the Disks Realistic?

Vorobyov & Basu (2005, 2006, 2010)Dunham, Vorobyov, & Arce (2014), submitted

Mass-Dependent Accretion

Comparing Apples and Oranges?

Are we comparing to the correct observed distribution?

Kryukova et al. (2012); Dunham et al. (2013)

Core Association(Dunham et al. 2013)

IR Colors(Kryukova et al. 2012)

• Deeper dense core surveys

• Surveys for dense gas

• Proper motion studies

Prospects for Resolution

Refine the sample of protostars and luminosity measurements

(Relatively simple to do in the near future)

Make sure modelers and observers are comparing the same quantities

(Best way to do this?)

Compare to more than just luminosity distribution

(BLT distribution, Class 0 vs. I lifetimes and luminosity distributions, disk masses, protostellar masses [eventually], …)

Constrain the frequency, timescales and amplitudes of variability

Future Directions