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Performance of Adaptive Optics in Large Telescopes:Application to very low-mass objects

Performance of Adaptive Optics in Large Telescopes:Application to very low-mass objects. Eduardo L. Martin Institute for Astronomy University of Hawaii. Operating AO Instruments in Mauna Kea. PUEO: 19 element curvature wavefront sensor at the 3.6-meter CFHT. Open for use since 1996.

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Performance of Adaptive Optics in Large Telescopes:Application to very low-mass objects

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  1. Performance of Adaptive Optics in Large Telescopes:Application to very low-mass objects Eduardo L. Martin Institute for Astronomy University of Hawaii

  2. Operating AO Instruments in Mauna Kea • PUEO: 19 element curvature wavefront sensor at the 3.6-meter CFHT. Open for use since 1996. • Hokupa’a:36-element curvature wavefront sensor built by the University of Hawaii. Visiting instrument at the 8.1-meter Gemini telescope from 1999 to 2002. • AO facility on the Keck 10-meter telescope. 349-element deformable mirror. Open since1999. • Subaru AO system:36-element curvature system. First light in December 2000.

  3. Focus on Very Low-Mass Objects • This presentation will focus on results obtained by University of Hawaii researchers using AO systems in Mauna Kea, which are relevant to the topic of low-mass stars, brown dwarfs and extrasolar planets. • Other AO applications include sharp images of solar system objects and star-forming regions, as well as studies of the Galactic Center and AGNs.

  4. The Impact of AO on Very Low-Mass Object Research • High spatial resolution allows to resolve close binaries and determine masses. This is particularly important for brown dwarfs because their masses are not known directly, but inferred from evolutionary models. • High dynamical range allows to detect very-low mass companions and circumstellar disks around stars

  5. A Double Brown Dwarf • Using Keck/AO, Martin et al. (2000) found that the M8.5 companion to the nearby star Gl569 is double, with a separation of 0.1”, corresponding to a projected semi-major axis of ~1 AU for a distance of 9.8 parsec.

  6. Orbital motion of Gl 569 B and C • Gl 569 B and C have been monitored with Keck AO since its discovery in August 1999. • The separation varies from 0.1” to 0.07”

  7. Dynamical Substellar Masses of Gl 569 B and C • Lane et al. (2001) obtained the following orbital parameters: Period=892days, eccentricity=0.3, semi-major axis=0.9AU. • The masses are substellar, with an allowed range between 0.078 -0.055 Ms for Gl569B and 0.070-0.048Ms for Gl569C. • The age is ~300 Myr from evolutionary models of brown dwarfs.

  8. AO Survey of Ultracool M Dwarfs • The Hokupa’a AO system on the Gemini telescope allowed for first time to guide on ultracool M dwarfs with Vmag~20. • Four binaries discovered with separations in the range 0.15” to 0.57” (4-14 AU) out of a sample of 20 M8-M9 dwarfs. Close et al. (2002).

  9. A Close VLM Companion to a Nearby Solar Analog • Primary: HR7672, G1V, V=5.8, d=17.7pc • Companion discovered with Hokupa’a AO/Gemini, separation=0.8”, 8.6 magnitudes fainter than the star in K’-band (2.2 microns), Liu et al. (2002).

  10. AO Proper Motion and Spectroscopy of HR7672B • AO imaging six months after discovery confirms that HR7672B has the same proper motion as the nearby star • AO-fed spectroscopy with Keck/NIRSPEC gives a spectral type ~L4 • Cumming et al. 1999 had found Msini=66 Mjup.

  11. A Brown Dwarf Binary Close to a Young Solar Analog • Primary: HR5534,G2V,V=5.9, Rotation P=7.8 days, active chromosphere, likely member of Ursa Major stream, age~300 Myr • Companion discovered with Hokupa’a AO/Gemini, separation 2.6”, 8 magnitudes fainter than star in H-band (1.6 microns). Potter et al. (2002).

  12. AO Proper Motion and Spectroscopy of HR5534B and C • AO observations 204 days after discovery confirm common proper motion. • Keck/AO NIRSPEC spectroscopy of each one of the two brown dwarfs (separation 0.13” or 2.3 AU) allow to derive spectral type ~L3.

  13. Polarized Circumstellar Disks and Jets • Hokupa’a AO system has a polarization dual image capability. • Disk and jet discovered around classical T Tauri star in rho-Ophiucus (Martin & Potter 2002)

  14. Conclusions AO capabilities in large-aperture, ground based, telescopes are operating routinely and producing wonderful scientific results such as detections of brown dwarf binaries, which are isolated or close to stars, and circumstellar disks. Hokupa’a is a curvature AO system capable of guiding with moderately faint guide stars. It could be installed in the GTC in 2003-2004 as a visitor instrument.

  15. Final comments • Gracias a Ramon Garcia Lopez for giving my talk on short notice. • Thanks to the organizers for including my contribution in the busy and exciting program of the great science to come from the GTC. • My broken bone is getting glued. I hope to attend the second GTC science meeting. • Hasta pronto!!

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