High‐Resolution Images of Orbital Motion in the Trapezium Cluster: First Scientific Results from the Multiple Mirror Telescope Deformable Secondary Mirror Adaptive Optics System1
| Autor: | Manny Montoya, R. G. Allen, Nick Siegler, R. Sosa, Mario Rascon, Armando Riccardi, Dylan Curley, Donald W. McCarthy, Hubert M. Martin, Piero Salinari, Francois Wildi, Michael Lloyd-Hart, Don Fisher, Doug Miller, Matt Rademacher, Roger Angel, Wolfgang J. Duschl, Guido Brusa, Laird M. Close |
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| Rok vydání: | 2003 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences media_common.quotation_subject Brown dwarf Astronomy and Astrophysics Astrophysics 01 natural sciences law.invention Telescope Stars Space and Planetary Science law Sky 0103 physical sciences Orbital motion Secondary mirror Low Mass Adaptive optics 010303 astronomy & astrophysics 0105 earth and related environmental sciences media_common |
| Zdroj: | The Astrophysical Journal. 599:537-547 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/379150 |
| Popis: | We present the first scientific images obtained with a deformable secondary mirror adaptive optics (AO) system. We utilized the 6.5 m Multiple Mirror Telescope adaptive optics system to produce high-resolution (FWHM ¼ 0>07) near-infrared (1.6 lm) images of the young (� 1 Myr) Orion Trapezium � 1 Ori cluster members. A combination of high spatial resolution and high signal-to-noise ratio allowed the positions of these stars to be measured to within � 0>003 accuracies. We also present slightly lower resolution (FWHM � 0>085) images from Gemini with the Hokupa‘a AO system as well. Including previous speckle data from Weigelt et al., we analyze a 6 yr baseline of high-resolution observations of this cluster. Over this baseline we are sensitive to relative proper motions of only � 0>002 yr � 1 (4.2 km s � 1 at 450 pc). At such sensitivities we detect orbital motion in the very tight � 1 Ori B2-B3 (52 AU separation) and � 1 Ori A1-A2 (94 AU separation) systems. The relative velocity in the � 1 Ori B2-B3 system is 4:2 � 2: 1k m s � 1 . We observe 16:5 � 5: 7k m s � 1 of relative motion in the � 1 Ori A1-A2 system. These velocities are consistent with those independently observed by Schertl et al. with speckle interferometry, giving us confidence that these very small (� 0>002 yr � 1 ) orbital motions are real. All five members of the � 1 Ori B system appear likely gravitationally bound (B2-B3 is moving at � 1.4 km s � 1 in the plane of the sky with respect to B1, where Vesc � 6k m s � 1 for the B group). The very lowest mass member of the � 1 Ori B system (B4) has K 0 � 11:66 and an estimated mass of � 0.2 M� . Very little motion (4 � 15 km s � 1 ) of B4 was detected with respect to B1 or B2; hence, B4 is possibly part of the � 1 Ori B group. We suspect that if this very low mass member is physically associated, it most likely is in an unstable (nonhierarchical) orbital position and will soon be ejected from the group. The � 1 Ori B system appears to be a good example of a star formation ‘‘ minicluster,’’ which may eject the lowest mass members of the cluster in the near future. This ‘‘ ejection ’’ process could play a major role in the formation of low-mass stars and brown dwarfs. Subject headings: binaries: general — instrumentation: adaptive optics — stars: evolution — stars: formation — stars: low-mass, brown dwarfs On-line material: color figures |
| Databáze: | OpenAIRE |
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