Space Interferometry Mission: Planets & More

1. Space Interferometry Mission: Planets & More S. R. Kulkarni California Insitute of Technology

2. Key Goals • Inventory of Extra-solar planets • Search for terrestrial mass planets • Accurate Cosmic Distance Scale • Measure the Age of the Universe • Determine Mass & Matter Makeup of Galaxy • Fundamental Stellar Astronomy • Define Fundamental Astrometric Frame

3. SIM: Modes • Wide Angle Astrometry: Distance & Dynamics position (ra, dec) & proper motion: 4 microarcsec • Narrow Angle Astrometry: Planets angular difference: 1 microarcsecond (These are the precision to be achieved by end of mission)

4. The Distance & Age Scale • Cepheid distance to 1% • RR Lyrae stars in globular clusters Turnoff stars & estimate cluster age • Rotational parallaxes to nearby galaxes

5. Dynamics of Galaxies Dark Matter and Merger History • Gravitational potential of Milky Way - 3-d velocities of targets (to 100 kpc) tidal streams • Dynamics of Local group and nearby galaxies - proper motion of V=16-20 mag stars

6. SIM: A Michelson Interferometer Three Colinear Fixed Baseline Interferometers Baseline: 10 m Wavelength: 0.4-1 micron (CCD) Aperture: 0.3 m Field of View: 0.3 arcsecond Resolution: 10 milliarcsecond Orbit: Earth Trailing (SIRTF) Launch: 2009 Lifetime: 5 yr (10 yr?)

7. How does SIM work? Basic Interferometry Equation: Delay = B . s + C B = baseline s = source direction C = instrumental constant Stabilize with 2 grid stars observed with “guide” interferometers Measure B from observations of grid stars Measure Delay with “science” interferometers http://planetquest.jpl.nasa.gov/simcraft/sim_frames.html

8. SIM & Son of SIM • 15 external metrology beams (simpler • because they’re not deployed) • No deployed boom • 4 siderostats (8 telescopes) • 10m baseline only, for science • No Beam switchyard • No nulling beam combiner • http://planetquest.jpl.nasa.gov/simcraft/sim_frames.html • 36 external metrology beams • 9m deployed boom (for external metrology) • 7 siderostats/telescopes 1m to 10m baseline • Beam switchyard to combine any 2 • telescopes • 4 astrometric beam combiners, 1 nulling • combiner

9. Rescoped Capabilities • Requirement: 30 microarcsecond Goal: 4 microarcsecond • Narrow Angle Astrometry Requirement: 3 microarcsecond Goal: 1 microarcsecond • Wide Angle Astrometry LOST Capabilities Imaging (no variable baselines) Nulling

10. Reference Frame: Critical SIM Frame: 3,000 metal poor K giants Tile: 15 degree diameter “Field of Regard” (FOR) or Tile Overlap: 12 stars in any FOR Grid Campaigns: 25% of mission lifetime

11. The 15-degree SIM Field of Regard is large enough to include most of Orion. A set of measurements within the same field of regard, about an hour long, forms a “tile.” The bright star on the upper left is the red giant Betelgeuse. Red giants will form the grid of 1302 stars whose positions will be used to assess the attitude and length of the science baseline during each “tile”.

12. Wide Angle: Comparison

13. Narrow Angle Astrometry Measure REFERENCE-TARGET angle Ideally, REFERENCE star will be: - Bright (10 mag) - Close on sky (avoid field errors) - must lack planets

14. Planet Detection: Comparison Detection Limits SIM: 1 as over 5 years (mission lifetime) Keck Interferometer: 20 as over 10 years

15. Astrometry Yields All Orbital Parameters 1A.U. ~ 150,000,000 km Orbital Parameter Planetary Property Mass atmosphere? Semimajor axis temperature Eccentricity variation of temp Orbit Inclination Period (coplanarity) ~80 A.U.

16. Reference Stars: Requirements Reference stars should not have planets! • Moderate distance K giants (mini-grid) or • Eccentric Binaries

17. Reference Star: K giants Considerable Preparatory Work: Identification & Stability

18. Reference Stars: Eccentric G star binaries Eccentric binaries do not possess planets over a range of orbital separation. Risk: Uneasy Feeling

19. Accuracy & Precision • 1 mas ( 5 picoradian) is 50 picometers. - No mechanical structure is this accurate or even this stable. - No optical surface is this accurate. • SIM achieves the required precision: • Metrology (measures changes in the optical bench) • Calibration (to remove biases due to imperfect optics) - Rapid Chopping (30 to 60 sec) to overcome thermal instability

20. Planet Detection: Comparison KI PTI CCD Photo Single measurement accuracy SIM Hip. GAIA FAME • SIM has highest sensitivity (fainter targets) • SIM is a pointed spacecraft - optimize for planet detection/orbit determination • GAIA (FAME) are scanner • End of Mission precision for SIM is 20 times better than GAIA 100 mas 1 mas 100 µas 1 µas 10 mas 10 µas

21. SIM Science Team Name Institution Key Project Dr, Geoffrey Marcy University of California, Berkeley Planetary Systems Dr. Michael Shao NASA/JP (science team chair) Extrasolar Planets (EPIcS) Dr. Charles Beichman NASA/JPL Young Planetary Systems and Stars Dr. Todd Henry Georgia State University Stellar Mass-Luminosity Relation Dr. Steven Majewski University of Virginia Measuring the Milky Way Dr. Brian Chaboyer Dartmouth College Pop II & Globular Clusters (Age) Dr. Andrew Gould Ohio State University Astrometric Micro-Lensing Dr. Edward Shaya Raytheon ITSS Corporation Dynamic Observations of Galaxies Dr. Kenneth Johnston U.S. Naval Observatory Reference Frame-Tie Objects Dr. Ann Wehrle NASA/JPL Active Galactic Nuclei Mission Scientists Dr. Guy Worthey Washington State Education & Public Outreach Scientist Dr. Andreas Quirrenbach University of California, San Diego Data Scientist Dr. Stuart Shaklan JPL Instrument Scientist Dr. Shrinivas Kulkarni California Institute of Technology Interdisciplinary Scientist Dr. Ronald Allen Space Telescope Science Institute Imaging and Nulling Scientist

22. Knowledge and Ignorance of Extrasolar Planets What we know: Eccentric orbits are common: scattering? • Several multiple systems of giant planets are known • Mass distribution extends below Saturn mass • Giant-Planet occurrence is high: ~7%

23. Knowledge and Ignorance of Extrasolar Planets • What we don’t know • Existence of terrestrial planets • Planetary system architecture • Mass distribution • Coplanarity of orbits, eccentricities • Only astrometry measures the mass of a planet unambiguously • Low-mass planets (rocky) in ‘habitable zone’ ?

24. EPIcs: A two-pronged search Known extra-solar system planets (7%) are different (orbital period and eccentricity distribution) Two possibilities: • Solar System is unique. • Planetary Systems are ubiquitous BUT diverse Tier 1-Tier Program 100 nearby stars at 1.5 microarcsec 1000 nearby stars at 4 microarcsec

25. Extra-solar Planet Interferometric Survey(EPIcS) M. Shao & S. R. Kulkarni (Co-PI) S. Baliunas C. Beichman A. Boden D. Kirkpatrick D. Lin D. Stevenson T. Loredo S. Unwin D. Queloz S. Shaklan C. Gelino  just joined S. Tremaine A. Wolszczan http://www.astro.caltech.edu/~srk

26. Tier-1: Search for Terrestrial Planets ~ 100 of the nearest stars (FGK) • Habitable zone • Sensitivity: ~3 Me

27. Tier-2 Sample 1000 stars in approx. 30-pc radius • Span the spectral range • Span range of ages • Span range of metallicty • Span range of debris disks (SIRTF) • Binary Stars

28. Tier-2 Addresses Broad Issues • What is the mass function of planets? • How is composition related to mass? [sub-Jupiters, superGanymede] • How common are terrestrial planets? • How does the presence of planet affect others? • How do properties of planetary systems depend on the nature of their host stars?

29. SIM’s anticipated Contribution • First terrestrial planets (within 10 pc) • Comprehensive view of planetary architecture • Unambiguous masses of known planets • Planetary Demographics • Reconnaissance for TPF • Specific targets for TPF around nearby stars • Target masses known (needed to calculate planet density)

30. Interdisciplinary Program S. R. Kulkarni (PI), B. Hansen, E. S. Phinney, M. H. van Kerkwijk, G. Vasisht Goals: • Planets around white dwarfs • Masses of neutron stars and black holes • Distances (hence radii) of neutron stars (e.g. Cen X-4) • Origin of high latitude OB stars & velocity kicks • Frame tie between SIM and ecliptic coordinate system

31. Now! • Palomar Testbed Interferometer Development of Phase referencing (B. Lane PhD) M-dwarf diameters Cepheid Pulsations • Keck Interferometer Fundamental Stellar Astronomy (Comm. Team) • Binaries: Very Narrow Angle Interferometry Adaptive Optics Precision Radial Velocity

32. Astrometry: Regimes

33. Very Narrow Angle Astrometry Shao & Colavita

35. The Gl 569 System • Apparent binary star system located at a distance of 9.8 pc • Primary is a M0V • Companion located ~5 arcsec away. Appears to be late-M type.

37. The Orbit of Gl 569 B P = 892 ± 25 d a = 0.90 ± 0.02 AU e = 0.32 ± 0.02 i = 34 ± 3 deg Residuals ~ 2 mas

38. The Total Mass of the System • From the period and semi-major axis we can determine the total mass of the Ba-Bb pair to high precision • 3 upper mass limit for the pair is 0.148 Solar masses

39. Palomar Testbed Interferometer • 100-m baseline, 40-cm siderostats • H, K bands • Highlights: M dwarf diameter determination Pulsations of Cepheid variable Herbig Ae/Be star

40. Distance to Pleiades via AtlasX-P Pan, M. Shao & S. Kulkarni(Nature, negotiating with Editor) • Pleiades is a gold standard for intermediate mass stars, brown dwarfs and Cepheid distance scale • Hipparcos team published distance to Pleiades D = 118 +/- 4 pc • Traditional distance (color-mag diagram) D = 131 +/- 3 pc Hipparcos result generated “lively” controversy.

41. Orbit of Atlas (Mark III & PTI) P(orbit)= 291day a = 13 mas e = 0.245 Inclination=108d

42. Distance via Kepler’s 3rd law A3 = d3 a3= (m1+m2)P2

43. Search for Planets in Speckle Binaries • Lane and Mutterspaugh have demonstrated very narrow angle astrometry with PTI (fringe scanning) • We are starting a 3-yr survey to search astrometrically for planets -> achieved 20 microarcsec • Konacki has successfully achieved 10 m/s RV for binary stars with HIRES

44. IR Spectroscopy Resulting spectral types: M8.5 and M9