Distinguishing Brownies from Fudge: The Low-Mass IMF the Companion Mass Ratio Distribution Michael R. Meyer Institute for Astronomy, ETH-Zurich Morten Andersen, Julia Greissl, and Alan Aversa Steward Observatory, The University of Arizona Formation of Brown Dwarfs: ESA-CONSTELLATION Workshop ESTEC, The Netherlands, 9-11 September, 2009

No local variations in stellar IMF (e.g. Meyer et al. 2000). See also Lada & Lada (2003).

What about the sub-stellar IMF ? cf. Luhman et al. PPV (2007) See also Muench et al. (2002).

Low Mass Stars and Sub-stellar Objects in NGC 1333 Wilking, Meyer, Greene, Mihail, & Carson (2004)

Near-IR Spectra of Low Mass Stars and Sub-stellar Objects Greissl, Meyer, Wilking, Fanetti, Greene, Scheider, Young (2007)

H-R Diagrams for Sub-stellar Objects in NGC 1333 * Greissl, Meyer, Wilking, Fanetti, Greene, Schneider, Young (2007)

NICMOS Color-Magnitude Diagram for NGC 1333 Greissl, Meyer, Wilking, Fanetti, Greene, Scheider, Young (2007)

Ratio of Stars to Sub-stellar Objects for 7 Young Clusters Andersen et al. (2008)

Ratio of Stars to Sub-stellar Objects for 7 Young Clusters Andersen et al. (2008)

Replacing the K-S Statistic: Binomial Tail Product? Andersen et al. (2008)

Replacing the K-S Statistic: Binomial Tail Product? Andersen et al. (2008)

Replacing the K-S Statistic: Binomial Tail Product? Andersen et al. (2008)

Probability of Various B-T-P for 7 Young Clusters: Bottom Line - Flat or Rising IMF Ruled Out (P < 0.01 %). Median BTP: 0.57 = 7.8 x 10-3 Andersen et al. (2008)

Probability of Various B-T-P for 7 Young Clusters: Bottom Line - Flat or Rising IMF Ruled Out (P < 0.01 %). Cf. Mean Mass of log-normal 0.1-0.3 Msun? Covey et al. (2008)

The Companion Mass Ratio Distribution (Duquennoy & Mayor, 1991) Frequency Separation (AU) Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

The Companion Mass Ratio Distribution (Duquennoy & Mayor, 1991) Frequency Separation (AU) Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

The Companion Mass Ratio Distribution (Duquennoy & Mayor, 1991) Frequency Separation (AU) Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

The Companion Mass Ratio Distribution (cf. Chabrier 2005) Frequency Primary Mass Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

The Companion Mass Ratio Distribution (cf. Chabrier, 2005) Frequency Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

The Companion Mass Ratio Distribution (cf. Chabrier, 2005) Frequency Mc/Mp Cf. Lada (2006); Burgasser et al. (2007); Metchev et al. (2009); Apai et al. (in prep)

Executive Summary The IMF turns over at low masses: there are fewer brown dwarfs compared to stars (Andersen et al. 2008). Determining the companion mass ratio distribution (vs. primary star mass/separation) down to Jupiter masses could discern differences between brown dwarfs and planets (Apai et al. in preparation).

The Search for Variations: A Six-Parameter IMF 1. Mean Mass 5. Sub-stellar Break log[N*] 3. High Mass Break 2. Variance 6. Sub-stellar Slope 4. High Mass Slope -2 -1 0 1 2 log[M*/Mo]