Wang, Q. D. and Dong, H. and Cotera, A. and Stolovy, S. and Morris, M. and Lang, C. C. and Muno, M. P. and Schneider, G. and Calzetti, D. (2010) HST/NICMOS Paschen-α Survey of the Galactic Centre: Overview. Monthly Notices of the Royal Astronomical Society, 402 (2 ). pp. 895-902. ISSN 0035-8711 http://resolver.caltech.edu/CaltechAUTHORS:20100224-112021406
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We have recently carried out the first wide-field hydrogen Paschen-α line imaging survey of the Galactic Centre using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument aboard the Hubble Space Telescope. The survey maps out a region of 2253 pc^2 (416 arcmin^2) around the central supermassive black hole (Sgr A*) in the 1.87 and 1.90 μm narrow bands with a spatial resolution of ~0.01 pc (0.2 arcsec full width at half-maximum) at a distance of 8 kpc. Here, we present an overview of the observations, data reduction, preliminary results and potential scientific implications, as well as a description of the rationale and design of the survey. We have produced mosaic maps of the Paschen-α line and continuum emission, giving an unprecedentedly high-resolution and high-sensitivity panoramic view of stars and photoionized gas in the nuclear environment of the Galaxy. We detect a significant number of previously undetected stars with Paschen-α in emission. They are most likely massive stars with strong winds, as confirmed by our initial follow-up spectroscopic observations. About half of the newly detected massive stars are found outside the known clusters (Arches, Quintuplet and Central). Many previously known diffuse thermal features are now resolved into arrays of intriguingly fine linear filaments indicating a profound role of magnetic fields in sculpting the gas. The bright spiral-like Paschen-α emission around Sgr A* is seen to be well confined within the known dusty torus. In the directions roughly perpendicular to it, we further detect faint, diffuse Paschen-α emission features, which, like earlier radio images, suggest an outflow from the structure. In addition, we detect various compact Paschen-α nebulae, probably tracing the accretion and/or ejection of stars at various evolutionary stages. Multiwavelength comparisons together with follow-up observations are helping us to address such questions as where and how massive stars form, how stellar clusters are disrupted, how massive stars shape and heat the surrounding medium, how various phases of this medium are interspersed and how the supermassive black hole interacts with its environment.
|Additional Information:||© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 November 2. Received 2009 October 29; in original form 2009 September 22. We gratefully acknowledge the support of the staff at STScI for implementing the survey and for helping in the data reduction and analysis. Support for program HST-GO-11120 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.|
|Subject Keywords:||circumstellar matter; stars: formation; Galaxy: centre; infrared: stars|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||24 Feb 2010 21:42|
|Last Modified:||26 Dec 2012 11:47|
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