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Information about IntroMiscConcl

Published on February 27, 2008

Author: Lassie


Slide1:  The slides in this collection are all related and should be useful in preparing a presentation on SIM PlanetQuest. Note, however, that there is some redundancy in the collection to allow users to choose slides best suited to their needs. Slide2:  Presented by Presenter Using materials shamelessly stolen from the SIM PlanetQuest Science Team, the Internet, and some familiar motion pictures Slide3:  SIM PlanetQuest is part of NASA’s Origins Program Slide4:  Focus on manned mission to Moon and Mars, robotic exploration of solar system, and search for life around other stars Among 20 goals the President set for NASA is the following: “Conduct advanced telescope searches for Earth-like planets and habitable environments around other stars” International participation --- “This is not a race …” The Presidential Vision National Academy of Sciences:  National Academy of Sciences SIM was prioritized in the 1991 AASC report as the fourth-ranked space program of moderate class Science goals as specified in the 1991 report: “…definitive searches for planets around stars as far away as 500 light-years through the wobbles of the parent star, trigonometric determination of distances throughout the galaxy, and the study of the mass distributions of nearby galaxies from stellar orbits." 30 mas, V=20 (italics added) National Academy of Sciences (2):  National Academy of Sciences (2) The scientific capabilities explicitly called for by the 2001 AASC were ". . . [enabling] the discovery of planets much more similar to Earth in mass and orbit than those detectable now, and . . . [permitting] astronomers to survey the Milky Way Galaxy 1,000 times more accurately than is possible now." The report emphasized the "particular attraction" of the dual capability of the new SIM. The report of the 2001 AASC's Panel on Ultraviolet, Optical, and Infrared Astronomy from Space (UVOIR Panel), which contains more detailed and explicit statements about SIM and its scientific goals than those included in the main AASC report, stressed that "the primary scientific objective of the SIM mission is ultrahigh accuracy astrometry.” (italics added) Slide7:  What is NASA’s Astronomical Search for Origins? To understand how stars and planetary systems form and to determine whether life-sustaining planets exist around other stars. To understand how life originated on Earth and to determine if it began and may still exist elsewhere as well. To understand how galaxies formed in the early universe and to determine the role of galaxies in the appearance of stars, planetary systems and life. How to do that?:  How to do that? With SIM! How Precise is SIM?:  How Precise is SIM? Microarcsecond precision opens a new window to a multitude of phenomena observable with SIM. Reflex Motion of Sun from 100pc (axes 100 µas) Parallactic Displacement of Galactic Center Apparent Gravitational Displacement of a Distant Star due to Jupiter 1 degree away Jupiter Galilean Satellites Dia. = 1000-2000 mas How Precise is SIM?:  How Precise is SIM? Microarcsecond precision opens a new window to a multitude of phenomena observable with SIM. Why go to space ?:  Why go to space ? Space has no air Ground interferometers limited by atmosphere to ~1 mas over wide angles High precision metrology measurements can be made Space is quiet Optical Path Difference (OPD) and pointing jitter are easier to control Space can be made thermally benign stable thermal environment  stability of optical system Measuring Distances using parallax:  Parallax is a small effect: James Bradley searched for it in 1725 - but discovered Stellar Aberration instead (± 20 arcsec). Friedrich Wilhelm Bessel detected it in 1838 (< 0.5 arcsec). Nearest star (Proxima Cen) 0.77 arcsec Brightest Star (Sirius) 0.38 arcsec Galactic Center (8.5 kpc) 0.00012 arcsec = 118 mas Far edge of Galactic disk (~20 kpc) 50 mas Nearest spiral galaxy (Andromeda Galaxy) 1.3 mas Measuring Distances using parallax SIM Covers the Entire Galaxy:  SIM Covers the Entire Galaxy Hipparcos 100 pc What is a parsec? “Parallax of one arcsecond” At 1 pc Earth-Sun distance subtends 1 arcsec 1 parsec = 3.26 light-years ~ distance to closest stars What is a microarcsecond (µas)? 1 µas = 4.8 x 10-12 radians = thickness of a nickel at the distance of the Moon! Stellar Evolution and the Distance Scale:  Stellar Evolution and the Distance Scale Distances in the Universe are uncertain because we don’t know the distances to “standard candle” stars SIM will measure accurate distances Masses of most stars are very poorly known SIM will measure accurate masses (to 1%) by using binary orbits Stellar evolution models can’t be further tested without accurate masses for ‘exotic objects’ SIM will measure the masses of OB (massive) stars, supergiants, brown dwarfs Galaxies and Beyond:  Galaxies and Beyond Study the ‘classical’ problems of size, mass distribution, and rotational dynamics of the Milky Way galaxy. Dynamics of Galaxy Groups within 5 Mpc. Quasar Astrophysics SIM can determine if the visible light from quasars originates in hot gas around an accretion disk or from a relativistic plasma jet.. SIM can detect the orbital motions of two merging black holes in the centers of massive galaxies. Replace the current International Celestial Reference Frame. SIM PlanetQuest Science Summary:  SIM PlanetQuest Science Summary Planet searching: Search for astrometric signature of terrestrial planets around nearby stars Statistics and properties of planetary systems Distances and Luminosities: Calibration of the cosmic distance ‘ladder’ Ages of globular clusters Galaxy and star cluster dynamics and structure Mass distribution in the halo of our Galaxy Spiral structure of our Galaxy Internal dynamics of globular clusters Masses and distances to gravitational lenses Dynamics of our Local Group of galaxies Quasars Origin of light Binary black holes Imaging demonstration: Simple systems within 2 arcsec field of view SIM Science Summary (in descending order of size scale):  SIM Science Summary (in descending order of size scale) Proper motions of nearby active galactic nuclei Dynamics of our Local Group of galaxies Dwarf spheroidal galaxies - tidal tails Mass distribution in the halo of our Galaxy Spiral structure of our Galaxy Astrometric signatures of MACHO microlensing events SIM Science Summary (cont.):  SIM Science Summary (cont.) Internal dynamics of globular clusters Ages of globular clusters Accurate masses for low-mass binary stars Masses and evolution of stars in close binary systems Astrometric search for brown dwarfs and massive planets Astrometric search for planets around nearby stars Test General Relativistic effects in the Solar System Astrometry of minor bodies in the Solar System Slide19:  Searching for Other Earths and Unique SIM PlanetQuest Science:  Unique SIM PlanetQuest Science Obviously, high-precision orbits Many planets and astrophysical phenomena Link optical to radio reference frame (ICRF) Origin of radio emissions Stellar evolution theory Controversial issues in astronomy and astrophysics Star spots Mass of Galactic black holes, clustered around 7 M_solar? Short period signal measurement Signals with P=days are hard for non-pointed mission to study. esp. when multiple frequencies are present. Controversial Issues in Astronomy:  Controversial Issues in Astronomy Is it possible to have two perpendicular orbits ? (i= 84º and 82º, separately) Are Galactic black holes clustered at masses around 7M⊙? Is it possible to have a black-hole X-ray binary with distance of 190 pc (Hipparcos)? What is the upper mass limit of neutron stars? What is SIM PlanetQuest? :  What is SIM PlanetQuest? SIM is … the “planet scout”: SIM will help to identify planetary systems of interest to future missions SIM is … a yardstick to the stars: SIM will measure precise distances by simple triangulation to stars all over the Galaxy, and even out to the Magellanic Clouds SIM is … a technical marvel: SIM engineers have scheduled new inventions for precise measurement of spacecraft mechanical components SIM is … an odyssey: SIM scientists and engineers have been dedicated to this mission for more than 15 years Proto-type for “SIM for the Masses”:  Proto-type for “SIM for the Masses” Many open problems in stellar astrophysics are due to lack of knowledge about distances Our example: X-ray binaries AGB and post-AGB stars Extremely luminous stars Chemically peculiar stars … SIM accuracy outperforms GAIA, especially at the fainter end of its sensitivity range Attractive Features of SIM:  Attractive Features of SIM “Galactic reach”: 10μas is 20% luminosity error at 10 kpc Very precise for nearby stars (1% at 500pc) Modest projects (of order 10 stars) can be executed with a few hours of mission time Using SIM wide-angle data is easy Standard pipeline produces science-grade output Comparison of SIM with GAIA:  Comparison of SIM with GAIA Mission Accuracy (Parallax, as) Target Magnitude (V) SIM GAIA Each point represents a target requested by a SIM Key Project PI SIM Measurement Capabilities:  SIM Measurement Capabilities SIM has two primary astrometric observational modes Wide angle (global) astrometry Narrow angle (relative) astrometry Global Astrometry (inertial ref frame tied to Quasars) 4 µas (position, ~4.6 µas parallax, ~2 µas/yr prop motion) Mag limit to 20mag (18 mag ~2hr/target) Grid (set of stars ~5 Deg spacing over 4 pi) ~1300 stars and 25~50 QSO’s On average 10.5 mag K giants, down to ~ 12 mag Narrow angle astrometry (relative astrometry) Absolution positions and proper motion, parallaxes only as good as global astrometry. But relative positions, parallaxes, much better Single measurement accuracy 1 µas over 1 deg. (900 sec obs, 10 mag) Mission accuracy for 30 obs/5yrs ~0.2 µas. Miscellaneous Properties:  Miscellaneous Properties Crowded field astrometry This is an active area of study, preliminary results presented Identify two objects as two objects. With baseline rotation (synthesis imaging) resolution l/B ~12 µas Without baseline rotation (multi-color fringe synthesis) ~ 25 µas Photometry (in 80 spectral channels from 0.45 to 1.0 µm) < 1% Fringe visibility accuracy < 1% in each of 80 spectral channels. (dia of star ~ 6 µas could be measured to ~1%) Wavelength calibration (of 80 spectral channels) < 0.1 nm Searching for Planets with SIM:  Searching for Planets with SIM A Deep Search for Earths Focus on 60~250 stars like the Sun (F, G, K) within 20 pc Detection limit of ~3 Me at 10 pc Sensitivity limit of ~1.0 Me at 6 pc (if limited to 60 stars) Perhaps 7~8 times as many terrestrial planet as terrestrial planets in the HZ A Broad Survey for Planets Is our solar system unusual? Survey ~2,000 stars within ~50 pc with sensitivity to Neptune mass Expect to find ~400 planets (from current RV statistics) Planets around wide variety of stellar types Multiple planet systems Coplanarity Mass distribution Eccentricity and Orbit radius Evolution of Planets Survey ~200 1~50Myr stars How do systems evolve? Is the evolution conducive to the formation of Earth-like planets in stable orbits? Do multiple Jupiters form and only a few (or none) survive? What We Don’t Know Are planetary systems like our own common? What is the distribution of planetary masses? Only astrometry measures planet masses unambiguously Are there low-mass planets in ‘habitable zone’ ? Imaging With Interferometers:  Imaging With Interferometers SIM vs. HST/ACS Imaging Quality:  SIM vs. HST/ACS Imaging Quality If   1(1.4 nm @ 500 nm), then SIM appears to surpass HST/ACS: For r ≤ 0.5˝ on “direct” image For r ≤ 0.25˝ on the “direct subtracted” image Everywhere inside the 0. 9˝ stop on coronagraphic images Reason for this is the lack of correlation of “zonal errors” on SIM’s “aperture”. SIM observations simulated: 10 m & 8.5 m baselines 2 orientation angle intervals Bright star V = 10 30/3000 min. on-target time HST/ACS detection limits…:  HST/ACS detection limits… J. Krist (2004) SIM Science Team:  SIM Science Team Team Member Institution Area of Interest/Discipline Key Science Projects Dr. Geoffrey Marcy University of California, Berkeley Planetary Systems Dr. Michael Shao NASA/JPL Extrasolar Planets Dr. Charles Beichman NASA/JPL Young Planetary Systems and Stars Dr. Andrew Gould Ohio State University Astrometric Micro-Lensing Dr. Edward Shaya University of Maryland Dynamic Observations of Galaxies Dr. Kenneth Johnston U.S. Naval Observatory Reference Frame-Tie Objects Dr. Brian Chaboyer Dartmouth College Population II Distances & Globular Clusters Ages Dr. Todd Henry Georgia State University Stellar Mass-Luminosity Relation Dr. Steven Majewski University of Virginia Measuring the Milky Way Dr. Ann Wehrle NASA/JPL Active Galactic Nuclei Mission Scientists Dr. Guy Worthey Washington State University Education & Public Outreach Scientist Dr. Andreas Quirrenbach Leiden University Data Scientist Dr. Stuart Shaklan JPL Instrument Scientist Dr. Shrinivas Kulkarni California Institute of Technology Interdisciplinary Scientist Dr. Ronald Allen Space Telescope Science Institute Synthesis Imaging Scientist A universe to study….:  A universe to study….

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