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Michael R. Meyer Institute for Astronomy, ETH-Zurich

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Presentation on theme: "Michael R. Meyer Institute for Astronomy, ETH-Zurich"— Presentation transcript:

1 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

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

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

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

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

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

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

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

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

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

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

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

13 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)

14 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 Msun? Covey et al. (2008)

15 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)

16 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)

17 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)

18 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)

19 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)

20 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)

21 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).

22 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 log[M*/Mo]


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