1. September, 2011Poland Cepheid Multiplicity and Masses: Fundamental Parameters Nancy Remage Evans Ed Guinan Scott Engle Howard Bond Gail Schaefer Derck Massa Charles Proffit Alexey Rastorguev Natalia Gorynya Scott Wolk Massimo Marengo Margarita Karovska Ken Carpenter Erika Bohm-Vitense Joel Eaton Ignazio Pillitteri Leonid Berdnikov

2. Cepheids Extragalactic distance scale Stellar evolution: ``The Cepheid Mass Problem” Asteroseismology Star formation: massive binaries September 2011Poland

3. Outline Star Formation Binary Characteristics Hubble, Chandra, XMM Tr 16: X-Rays Masses: Evolution Velocity data September, 2011

4. Poland Cepheids 4-7 M  Formerly B stars Young ~50 Myr Post-RGB, core He burning Evolve without strong mass loss of O stars Known distances

5. September 2011 Part I: Multiplicity: Goals Star Formation Angular momentum Low mass: well characterized High mass: rarer, broad lines, mass loss Observations Binary, triple,…. Distribution of mass ratios Maximum separation HIGH VS LOW MASS STARS Poland

6. September, 2011Poland High Mass Companions: IUE Survey Particularly complete binary information: Evolved cool stars: sharp lines Hot companions dominate in UV Observed the 75 brightest Cepheids with IUE All companions through early A detected 21% companions Using R V : 34%

7. September, 2011Poland Energy Distributions Hot companions Normalized at 1600 A Generally very low reddening Well determined spectral types, mass

8. IUE Example Cepheid RT Aur Compared with main sequence stars September, 2011Poland RT Aur

9. September, 2011Poland Mass Ratios M 2 /M 1 Strong preference for low mass companions Selection: orbital periods longer than 1 year Contrast: binaries with P<40d: equal mass preference (Tokovinin, 2000)

10. September, 2011Poland Multiplicity: Completeness Cepheids with orbits 18 observed with IUE => hot companions known Multiplicity? M 2 unknown

11. September, 2011Poland UV high res Multiplicity: Completeness High resolution UV spectra (HST, IUE): velocity of companion 8 of 18 5 of 8 are triples

12. September, 2011Poland Multiplicity: Completeness Cepheids with orbits + companion spectrum 8 (possibly 9) are triple: 44% (50%) Triples

13. Hubble Snapshot Survey HST WFC3 V and I Eta Aql Hot companion known from IUE No orbital motion September, 2011Poland

14. Eta Aql: T Mon Subtracted September, 2011Poland

15. Binary Parameters IUE survey: identify all companions M > 2 M  15 Cepheids 11 have orbits, orb. motion => period 3 resolved with WFC3 => separation => period (Eta Aql, V659 Cen, S Nor) Compare distribution of separations of Cepheids (5 M  ) with solar mass stars (Raghavan et al., Duquennoy and Mayor) for q = M 2 /M 1 > 0.4 September, 2011Poland

16. Orbital Period Distributions Cepheids vs Solar mass stars: different period distribution for comparions with mass ratio > 0.4 September, 2011Poland CepheidsSolar Mass

17. Hubble Snapshot Survey: Goal 2: Low Mass Stars Resolved companions HST WFC3 l Car ~40” x 40” V and I Young low mass stars produce X-rays XMM image of l Car: no X-rays => old field stars September, 2011Poland

18. September, 2011Poland Low Mass Companions Alpha Per Cluster: age of a typical Cepheid Rosat observations: filled symbols are X-ray detections Essentially all stars cooler than F5 V Field stars would not be detected in X-rays

19. Poland Low-Mass Companions: Chandra Observation of Polaris Young, low mass stars prominent in X-rays Center 3’ of ACIS-I field Putative components marked A = Aa + Ab B F3 V C, D X-ray but no 2MASS: background AGN Resolved companions 15 mag fainter September 2011

20. HST Snapshot: Y Car September, 2011Poland

21. Low Mass Companions of B Stars B stars: comparable mass to Cepheids Late B stars: no X-rays X-rays taken to be from low mass companions Identified late B stars in Tr 16 using photometry and proper motions Chandra ACIS image: B stars: blue: detected; purple: not detected September, 2011Poland

22. Tr 16 Late B Stars September, 2011Poland X-rays: dot => low mass companion ( 1.4 to 0.5 M  ) 39% of late B stars Complementary estimate of more massive companions from IUE: 34% Preliminary: q < 0.1 lacking

23. September, 2011Poland Luminosity: mass of He burning core Core convective overshoot Rotation Radiative opacity Mass loss Part II: Masses as Evolutionary Benchmarks

24. September, 2011Poland Masses Problem: mass mismatch between evolutionary and pulsation masses Problem: blue loops

25. Measured Masses: Orbits Orbits:the basis for dynamical masses High quality radial velocities: Moscow Univ, CORAVEL, AST Eg V350 Sgr September, 2011Poland

26. September, 2011Poland Mass: Binary Stars Kepler’s Third Law P 2 (M 1 + M 2 ) = A 3 Solar system units P: period M 1, M 2 : masses A: semi-major axis (separation)

27. September, 2011Poland Masses of Galactic Cepheids How? Ground-based spectroscopic orbit Inclination Double-lined spectroscopic binaries:high resolution UV spectroscopy: orbital velocity amplitude ratio + mass of secondary Astrometric orbit of Cepheid (Benedict, et al.) + mass of secondary Astrometric orbit of both (Polaris)

28. September, 2011Poland Masses of Galactic Cepheids Padua, Geneva tracks: decreasing overshoot from left to right S Mus,V350 Sgr: HST velocities W Sgr, FF Aql: Benedict orbits Polaris: HST No overshoot

29. September, 2011Poland S Mus Hottest companion GHRS high resolution velocities Temperature

30. September, 2011Poland S Mus FUSE spectra Standards reddened to match S Mus H 2 absorption H2H2

31. September, 2011Poland S Mus Example S Mus, B3 V B5 V

32. September, 2011Poland W Sgr Spectroscopic orbit: 4.3 yr IUE: hot companion: A0 V Small orbital velocity amplitude: face- on? Inconsistent with reasonable Cepheid mass Resolved?

33. September, 2011Poland W Sgr B STIS spectrum Component B: resolved, hot Spectroscopic binary: Cepheid Aa + Ab, cool 2800 A 2625 A Ceph +Comp Ab Comp B 0.16”

34. September, 2011Poland W Sgr Solid: extracted Cepheid Aa+ Ab spectrum Dashed: Alp Aqr: slightly cooler than Cepheid Ab not detected M Ab < 1.4 M  M cep < 5.4 M 

35. September, 2011Poland Polaris: Orbit Pulsation velocity Orbit: Kamper (1996) Period: 30 years Amplitude : 3.7 km/s

36. September, 2011Poland Polaris: Inclination Wielen, et al. 2000 Hipparcos proper motion Nearly instantaneous in 30 year orbit Derive inclination 2 solutions

37. September, 2011Poland Polaris: HST HST ACS PSF Comparison: white dwarfs

38. September, 2011Poland Polaris: Mass Dynamical mass Aa 4.5 + 2.2 /-1.4 M  Ab 1.26 +/- 0.14  Orbital motion

39. September, 2011Poland Summary: Masses Masses: challenge to improve errors

40. Binary Properties (Return to Part I) Accurate velocities For some stars span of 30 years Identify velocity shift of 2 km/s between years (corrected for pulsation) September 2011Poland

41. Detection Probability (%) For an orbit with 5 Msun primary Ignore eccentricity For M 2, P compute orbital velocity Detect 2 km/s velocity shift Compute inclination (detection probability) Work in progress September 2011Poland P (yr) 131030 qM2M2 0.31.510099 97 0.10.598958977

42. Summary: Multiplicity New Multiwavelength Approaches/Results: 44% (maybe 50%) of binaries are triples Favor small mass ratios for P > 1 year HST high resolution images Period distribution: differences between high and low mass stars Resolved low mass companions: X-rays Late B stars: 39% low mass companions Velocities: orbits and limits September 2011Poland