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Future Spectroscopic Surveys of Stars

Future Spectroscopic Surveys of Stars. Carlos Allende Prieto Mullard Space Science Laboratory University College London. Overview. Galactic stars and Spectroscopic surveys Apache Point Observatory Galactic Evolution Experiment Gaia. NGC 7331 IR Spitzer.

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Future Spectroscopic Surveys of Stars

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  1. Future Spectroscopic Surveys of Stars Carlos Allende Prieto Mullard Space Science Laboratory University College London

  2. Overview • Galactic stars and Spectroscopic surveys • Apache Point Observatory Galactic Evolution Experiment • Gaia

  3. NGC 7331 IR Spitzer Smith et al. (2004); image courtesy NASA/JPL – Caltech/STScI LMU, October 8, 2007

  4. The Milky Way blue: 12 m green: 60 m red: 100 m IRAS – ipac/CalTech LMU, October 8, 2007

  5. The many uses of Galactic stars • Starcounts: structure | static view • Spectroscopy: evolution | dynamic view • Stellar Nucleosynthesis • Near-field Cosmology • Galaxy Evolution

  6. Galactic Formation and Evolution • Context: a  -CDM Universe • Does the Milky Way fit in that picture? • Observational Diagnostics: • Metallicity distributions • Abundance ratios • Stellar Ages • Kinematics

  7. FACT The Galaxy is a vast and complex stellar system. Large numbers of stars are necessary to make significant progress

  8. High-resolution Surveys: PAST • Friends of McDonald … Edvardsson et al. 1993, Reddy et al. 2003, 2006 Allende Prieto et al. 2004, Ramírez et al. 2007 • Fuhrmann’s Own Furhmann 1996, 1998, 2000, … 2008 • Geneva-Copenhagen Nordstrom et al. 2006, Holmberg et al. 2007 • Swedish group Feltzing & Gustafsson 1998, Bensby et al. 2004 …

  9. Low-resolution surveys: PAST • H&K Survey (Team Beers) • HES (Christlieb & Co.) • SDSS-I • SDSS-II (SEGUE) • Many other smaller surveys with up to a few thousand stars/ project (look for Carney, Ryan, Norris, Morrison, Wyse, Gilmore…)

  10. Galactic Formation and Evolution • Context: a  -CDM Universe • Does the Milky Way fit in that picture? • Observational Diagnostics: • Metallicity distributions • Abundance ratios • Stellar Ages • Kinematics

  11. Metallicity distributions Geneva-Copenhagen, S4N, Furhmann 08 Thin disk

  12. Metallicity distributions Thick disk SDSS spectra/ Allende Prieto+06

  13. Metallicity distributions HALO Metallicity distribution function (SDSS Allende Prieto 2008)‏ BUT pretty much ABSOLUTE IGNORANCE for the central parts of the Galaxy

  14. The Promise of Detailed Chemical Abundance Studies The Star Formation Rate McWilliam 1997 •  elements primarily contributed from Type II SNe • Type Ia start to contribute >~1 Gyr • Direct indicator of early star formation rate (SFR)‏

  15. Thick (red) and thin (black crosses) disks Reddy et al. 2006

  16. Reddy et al. 2006 Ramírez et al. 2007 (for oxygen)

  17. Galactic halo Cayrel+ 2004

  18. The Promise of Detailed Chemical Abundance Studies Disk + Halo Thick disk (Bensby et al.) K giants (Cunha & Smith 2006) M giants (Origlia & Rich 2005) Situation for the bulge is unclear -- much more and better data needed

  19. Allende Prieto et al. 2006

  20. Issues • Chemical and kinematic studies of the disk are limited to the ‘local’ disk • Samples (especially hi-res) are typically hand-picked and severely biased • Samples focused on a single (or two) populations: It is hard to connect the dots and remove potential biases across the Galaxy • The distant halo is poorly explored • Despite spectacular progress in terms of accuracy/statistics for the thin/thick disk, and the halo, the research is ~ 20 yr behind for the bulge and the central part of the Milky Way

  21. FUTURE SURVEYS • HIGH-RESOLUTION • RAVE (Radial Velocity Experiment) • SDSS-III: APOGEE (Apache Point Observatory Galactic Evolution Experiment) • Gaia • LOW-RESOLUTION • SDSS-III: SEGUE2 (Sloan Extension for Galactic Understanding and Exploration) • Gaia

  22. APOGEE: Uncharted Territory • Red giants/red clump have strong NIR flux. • Complete point source sky catalogue to H ~ 13.5 available from 2MASS • AH / AV = 0.17 • Access to dust-obscured galaxy • Velocities to <1 km/s accuracy and precision abundances for giants across the Galactic plane, bar, bulge, halo • Low atmospheric extinction makes bulge declinations accessible from North (though over smaller field)‏ • Avoids thermal background problems of even longer 

  23. Advantages of a High Resolution H-band Survey

  24. The APOGEE Survey: Some Goals • First 3-D chemical abundance distribution (many elements), MDFs across Galactic disk, bar, bulge, halo. • Probe correlations between chemistry and kinematics (note Gaia astrometry in 2017). • Constrain IMF and SFR of bulge/disk as function of radius, metallicity/age, chemical evolution of inner Galaxy. • Determine nature of Galactic bar and spiral arms and their influence on abundances/kinematics of disk/bulge stars. • Measure Galactic rotation curve (spec. , Gaia astrometry)‏ • Search for and probe chemistry/kinematics of (low-latitude) halo substructure (e.g., Monoceros Ring). • Combine with existing/expected optical, NIR and MIR data and map Galactic dust distribution, constrain variations in Galactic extinction law

  25. The APOGEE Survey: Basic Strategy • Strawman APOGEE instrument design: • Two Raytheon 20482 HgCdTe chips sampling, 1.7  cutoff • Sample 1.51-1.68 bandwindow • Large dewar in new APO lab (below MARVELS)‏ • 300 H-band optimal, dry fibers • R ~ 20,000 • Likely a VPH grating (1 versus 2 arms??) • Survey • On-line May, 2011 • Bright time, will require summer observing for bulge • ~3h integrations, S/N > 100 @ H = 13.5 • >100,000 stars across bulge, bar, disk • For b = 0o, can access -5o < l < 240o

  26. Target Selection • Only basic plan in place, specific selection TBD • Possible starting plan for disk/bulge • Shallow (1h) + deep (3h) samples? • 2MASS giants, red clump selection Known open/globular clusters • Provide absolute ages for SFH’s probed with abundances • First systematic, large-scale survey of planar clusters

  27. Anticipated Deliverables: • -calibrated, sky-subtracted, telluric absorption-corrected, 1-D spectra • RVs to ~0.5 km/s external accuracy • log(g), [Fe/H], Teff (making use of spectra + 2MASS colors) • (spectral synthesis) measurements of well-defined set of elemental abundances (e.g., CNO,  series, Fe-peak, Al, K)‏

  28. Can overlap many/most SEGUE fields (phot & spect)‏ • Pre-identification of interesting targets (metal-poor, streams, etc.) & deep photometry • Possibility for some neutron capture info

  29. Man Power • Proposal co-Is S. Majewski (PI), M. Skrutskie (Project Scientist), R. O’Connell (Steering Comm.), J. Wilson, R. Indebetouw, M. Nelson, R. Patterson, R. Rood, R. Schiavon (Survey Scientist) J. Bullock (UCI), J. Crane, A. McWilliam (OCIW), K. Cunha, V. Smith (NOAO-Gemini), D. Geisler (Concepcion), K. Johnston (Columbia), J. Munn (USNOFS), I.N. Reid (STScI), M. Shetrone (Texas), D. Spergel (Princeton), M. Asplund (MPA) M. Weinberg (Umass), C. Allende Prieto (UCL)‏, ***YOUR NAME HERE*** • Other • J. Frogel (AURA), S. Hawley (U. Wash.), P. Frinchaboy (Wisc.)‏

  30. SDSS-III BOSS * Will measure the cosmic distance scale via clustering in the large-scale galaxy distribution and the Lyman-α forest * Will map the structure, kinematics, and chemical evolution of the outer MilkyWay disk and halo * Will use high-resolution infrared spectroscopy to see through the dust to the inner Galaxy Will probe the population of giant planets via radial velocity monitoring of 11,000 stars SEGUE-2 APOGEE MARVELS

  31. 2008 2009 2010 2011 2012 2013 2014 SEG–2 BOSS MARVELS SDSS-II APOGEE SEGUE-2 piggyback SDSS-III Schedule

  32. Gaia Unraveling the chemical and dynamical history of our Galaxy

  33. Gaia: Design Considerations • Astrometry (V < 20): global astrometric reduction • completeness to 20 mag (on-board detection)  109 stars • accuracy: 10–25 μas at 15 mag (Hipparcos: 1 mas at 9 mag) • scanning satellite, two viewing directions • Photometry (V < 20): • astrophysical diagnostics (low-dispersion photometry) + chromaticity • Teff ~ 200 K, log g to 0.5 dex, [Fe/H] to 0.3 dex(?!), extinction • Radial velocity (V < 16–17): slitless spectroscopy 847-874 mm • third component of space motion, perspective acceleration • spectra: chemistry, rotation

  34. Stellar Astrophysics • Comprehensive luminosity calibration, for example: • distances to 1% for ~10 million stars to 2.5 kpc; to 10% for ~100 million stars to 25 kpc • rare stellar types and rapid evolutionary phases in large numbers • parallax calibration of all distance indicators e.g. Cepheids and RR Lyrae to LMC/SMC • Physical properties, for example: • solar neighbourhood luminosity function e.g. white dwarfs (~200,000) and brown dwarfs (~50,000) • luminosity function for pre main-sequence stars • Precise luminosities → precise stellar ages

  35. One Billion Stars in 3-d will Provide … • in our Galaxy … • the distance and velocity distributions of all stellar populations • large-scale surveys of extra-solar planets (~10–20,000) and Solar System bodies (~100,000) • … and beyond • definitive distance standards out to the LMC/SMC • rapid reaction alerts for supernovae and burst sources (~20,000) • QSO detection, redshifts, microlensing structure (~500,000)

  36. One Billion Stars in 3-d will NOT Provide … • The ability to chemically tag the different stellar populations, other than with [Fe/H] with uncertainties of ~0.3 dex RVS will only provide spectra with sufficient S/N • to measure chemical compositions down to V<13 • to measure radial velocities down to V<17 mag

  37. Exo-Planets: Expected Discoveries • Astrometric survey: • monitoring of hundreds of thousands of FGK stars to ~200 pc • masses, rather than lower limits (m sin i) • Results expected: • 10,000–20,000 exo-planets • orbits for ~5000 systems • masses down to 10 MEarth to 10 pc • Photometric transits: ~5000? Figure courtesy François Mignard

  38. Studies of the Solar System • Asteroids and other bodies: • 105–106 new objects expected (340,000 presently) • taxonomy/mineralogical composition • diameters for ~1000, masses for ~100 • Near-Earth Objects: • Amors, Apollos and Atens (1775, 2020, 336 known today) • ~1600 Earth-crossers >1 km predicted (100 currently known)

  39. Satellite and System • ESA-only mission • Launch date: 2011 • Lifetime: 5 years • Launcher: Soyuz–Fregat • Orbit: L2 • Ground station: New Norcia and/or Cebreros • Downlink rate: 4–8 Mbps • Mass: 2030 kg (payload 690 kg) • Power: 1720 W (payload 830 W) Figures courtesy EADS-Astrium

  40. Payload and Telescope Basic angle monitoring system Rotation axis (6 h) Two SiC primary mirrors 1.45  0.50 m2 at 106.5° SiC toroidal structure (optical bench) Combined focal plane (CCDs) Superposition of two Fields of View (FoV) Figure courtesy EADS-Astrium

  41. Figure courtesy Alex Short Focal Plane 104.26cm Wave Front Sensor Red Photometer CCDs Blue Photometer CCDs 42.35cm Wave Front Sensor Radial-Velocity Spectrometer CCDs Basic Angle Monitor Basic Angle Monitor Star motion in 10 s Sky Mapper CCDs Astrometric Field CCDs Sky mapper: - detects all objects to 20 mag - rejects cosmic-ray events - FoV discrimination Astrometry: - total detection noise: 6e- Total field: - active area: 0.75 deg2 - CCDs: 14 + 62 + 14 + 12 - 4500 x 1966 pixels (TDI) - pixel size = 10 µm x 30 µm = 59 mas x 177 mas Photometry: - spectro-photometer - blue and red CCDs Spectroscopy: - high-resolution spectra - red CCDs

  42. Sky Scanning Principle 45o Spin axis 45o to Sun Scan rate: 60 arcsec/s Spin period: 6 hours Figure courtesy Karen O’Flaherty

  43. Photometry Measurement Concept (2/2) RP spectrum of M dwarf (V=17.3) Red box: data sent to ground White contour: sky-background level Colour coding: signal intensity Figures courtesy Anthony Brown

  44. Radial Velocity Measurement Concept (1/2) Spectroscopy: 847–874 nm (resolution 11,500) Figures courtesy EADS-Astrium

  45. Radial Velocity Measurement Concept (2/2) RVS spectrograph CCD detectors Field of view Figures courtesy David Katz

  46. Scan width: 0.7° Sky scans (highest accuracy along scan) Data Reduction Principles 1. Object matching in successive scans 2. Attitude and calibrations are updated 3. Objects positions etc. are solved 4. Higher terms are solved 5. More scans are added 6. System is iterated Figure courtesy Michael Perryman

  47. Schedule 2020 2004 2008 2016 2000 2012 Concept & Technology Study (ESA) ESA acceptance Re-assessment: Ariane-5 Soyuz Technology Development Design, Build, Test Launch Cruise to L2 Observations Data Analysis Catalogue Early Data

  48. Gaia’s spectroscopy in perspective GAIA Vmag 6 < V < 13 (17) R 11,500 Δλ ~300 A Chemical ~5 Elements Log(Number of 6 Targets) Max(distance) ~1 kpc (5 kpc) SDSS (low) 14 < V <18 2,500 ~4000 A ~5 6 ~7 kpc (100 kpc) McD 2.7m -1 < V < 11 60,000 ~4000 A ~20 3 ~0.2 kpc (3 kpc)

  49. Gaia RVS in perspective McD 2.7m + HET/HRS Q=R Δλ GAIA (RVS Spectra) SDSS (low) Vmagnitude

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