What have we learned from Eclipsing Binaries in the Orion Nebula?

1. What have we learned from Eclipsing Binaries in the Orion Nebula? Keivan Guadalupe StassunVanderbilt University

2. Dynamical Masses of PMS Starscirca 2013 N=33M < 2 Msun Single stars • Circumstellar disk “rotation curve” Binary stars • Astrometric • Eclipsing

3. Accurate masses and radii: Eclipsing binaries V1174 Ori M1 = 1.01 ± 0.015 Msun M2 = 0.73 ± 0.008 Msun R1 = 1.34 ± 0.015 Rsun R2 = 1.07 ± 0.011 Rsun T1 = 4470 ± 120 K T2 = 3615 ± 10 K log g1 = 4.19 ± 0.01 log g2 = 4.25 ± 0.01 Masses, Radii, and Teff ratio measured very accurately. Luminosities are distance independent. Stassun et al. (2004)

4. Comparison of dynamical masses to theoretical models in HR diagram • Above 1 Msun: • Good agreement: Mean difference 10%, scatter ~10%. • Below 1 Msun: • Poorer agreement: Differences as large as ~100%, large scatter. • Best overall agreement: Siess et al (2000), and Palla & Stahler (1999): • Overall consistency to ~5%, though with scatter of ~25%. Updated from Hillenbrand & White (2004)

5. Case Study: Par 1802A pair of dissimilar ‘identical twins’ Alicia Aarnio (Michigan) Yilen Gómez (Vanderbilt) Phillip Cargile (Vanderbilt) Bob Mathieu (Wisconsin)

6. Par 1802: Non-coevality? In protobinary phase, original secondary preferentially accreted mass. Secondary ended accretion phase later. Apparent age difference because different t=0 due to different accretion histories. e.g. Simon & Stobie (2009), Clarke (2007), Bate (2004) M1 = 0.39 ± 0.02 Msun M2 = 0.38 ± 0.02 Msun q = 0.98 ± 0.01 T1/T2 = 1.092 ± 0.002 R1 = 1.82 ± 0.05 Rsun R2 = 1.69 ± 0.05 Rsun L1/L2 = 1.62 ± 0.03 Stassun et al. (Nature, 2008)

7. Par 1802: Tidal heating by third body? M1 = 0.39 ± 0.02 Msun M2 = 0.38 ± 0.02 Msun q = 0.98 ± 0.01 T1/T2 = 1.092 ± 0.002 R1 = 1.82 ± 0.05 Rsun R2 = 1.69 ± 0.05 Rsun L1/L2 = 1.62 ± 0.03 Stassun et al. (Nature, 2008) Gomez et al. (ApJ, 2012)

8. Triples among known PMS eclipsing binaries • 7 triples : 40 doubles = 18% (MS all; Duquennoy & Mayor 1991) • 2 triples : 19 doubles = 11% (PMS all; Ghez et al. 1997) • 8 triples : 13 doubles = 61% (PMS SBs; Guenther et al. 2007) • 8 triples : 6 doubles = 133% (PMS EBs; Stassun & Hebb in prep.)

9. Case Study: 2M0535-05The First Brown-Dwarf Eclipsing Binary Bob Mathieu (Wisconsin) Jeff Valenti (STScI) Yilen Gómez (Vanderbilt) Matthew Richardson (Vanderbilt)

10. Temperature reversal R1 = 0.67 ± 0.03 Rsun R2 = 0.51 ± 0.03 Rsun Stassun et al. (ApJ, 2007) M1 = 60 ± 3 MJup M2 = 39 ± 2 MJup T2/T1 = 1.051 Stassun et al. (Nature, 2006) Mohanty et al. (ApJ, 2009)

11. Primary BD has strong surface activity B ~ 4 kG Primary brown dwarf ~10 more magnetically active than secondary. Reiners et al. (ApJ, 2007) P1 = 3.293 ± 0.001 days P2 = 14.10 ± 0.05 days Gómez et al. (ApJ, 2009)

12. Active, primary brown dwarf shifted to cooler Teff, apparently lower mass 2M0535-05: Brown Dwarf Eclipsing Binary in Orion T2/T1 = 1.051±0.004 Stassun et al. (Nature 2006, ApJ 2007) 1 Myr Mohanty et al. (ApJ, 2009)Stassun et al. (ApJ, 2012)

13. Inflated R and Suppressed Teff in Active Low-mass Eclipsing Binaries Lopez-Morales (ApJ, 2007)Stassun et al. (ApJ, 2012) • Sample: • 11 stars in 7 EB systems • Direct, accurate masses, radii, and Teff • X-ray luminosity measurements • LX to LHa relation of Scholz et al. (2007)

14. Inflated R and Suppressed Teff in Active Field M-dwarfs Morales et al. (AJ, 2008)Stassun et al. (ApJ, 2012) • Sample: • PMSU catalog • 700 M-dwarfs with distances, spectral types, K mags, Ha measures • Radii via Stefan-Boltzmann law • Masses via BCAH98 tracks

15. An Empirical Relation Linking R Inflation and Teff Suppression to HaEmission Stassun et al. (ApJ, 2012) • Applicability: • M < 0.8 Msun • -4.6 < log LHa/Lbol < -3.3

16. Primary brown dwarf in 2M0535-05 effectively corrected in HR diagram 1 Myr Stassun et al. (ApJ, 2012)

17. New generation PMS models: Incorporating effects of magnetic activity Torres et al. (ApJ, 2013) New models show promise when compared to PMS EBs: 2-3x better agreement with dynamical masses(Stassun, Feiden, & Torres, in prep.) New models incorporating magnetic field effects on stellar structure and evolution can successfully explain R inflation(Feiden & Chaboyer, ApJ 2012)

18. Summary • Large uncertainties remain in theoretical stellar evolution models. • Some models perform better than others in HR diagram, but… • PMS is complex: activity effects, accretion histories, third bodies • Magnetic activity alters Teff and R of low-mass stars and brown dwarfs (but Lbol appears to be ok). • Beware mass and age estimates for active low-mass field objects: Teff or color based mass estimates can be too low by factor of ~2. • Empirical relations useful for correcting Teff, R, and M estimates via Ha. • Apparent non-coevality of ~50% possible in low-mass binaries at ~1 Myr. • Accretion history of protobinaries may be important for setting final masses. • Tidal heating history and role of third bodies may be important for observed luminosities. • New PMS models incorporating magnetic effects show promise.

19. Josh Pepper (Lehigh) Fabienne Bastien (Vanderbilt) Gibor Basri (Berkeley)

20. Measuring stellar structure from “flicker” and “crackle” Bastien et al. (2013, Nature)

21. Measuring stellar structure from “flicker” and “crackle” Bastien et al. (2013, Nature)

22. http://filtergraph.vanderbilt.edu/