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Title: THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3

Abstract

Spectrophotometric distances in the K band have been reported by different authors for a number of obscured Galactic H II regions. Almost 50% of them show large discrepancies compared to the classical method using radial velocities measured in the radio spectral region. In order to provide a crucial test of both methods, we selected a target that does not present particular difficulty for any method and which has been measured by as many techniques as possible. The W3 star-forming complex, located in the Perseus arm, offers a splendid opportunity for such a task. We used the Near-Infrared Integral Field Spectrograph on the Frederick C. Gillett Gemini North telescope to classify candidate 'naked photosphere' OB stars based on Two Micron All Sky Survey photometry. Two of the targets are revealed to be mid-O-type main-sequence stars leading to a distance of d = 2.20 kpc. This is in excellent agreement with the spectrophotometric distance derived in the optical band (d = 2.18 pc) and with a measurement of the W3 trigonometric parallax (d = 1.95 kpc). Such results confirm that the spectrophotometric distances in the K band are reliable. The radio-derived kinematic distance, on the contrary, gives a distance twice as largemore » (d = 4.2 kpc). This indicates that this region of the Perseus arm does not follow the Galactic rotation curve, and this may also be the case for other H II regions for which discrepancies have been found.« less

Authors:
; ; ;  [1];  [2];  [3]
  1. Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, 05508-090 Sao Paulo, SP (Brazil)
  2. NOAO, Tucson, AZ 85719 (United States)
  3. JILA, University of Colorado, Boulder, CO 80309-0440 (United States)
Publication Date:
OSTI Identifier:
21582999
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 142; Journal Issue: 3; Other Information: DOI: 10.1088/0004-6256/142/3/67; Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTANCE; MAIN SEQUENCE STARS; PHOTOMETRY; RADIAL VELOCITY; ROTATION; SPECTROPHOTOMETRY; TELESCOPES; MOTION; STARS; VELOCITY

Citation Formats

Navarete, F., Figueredo, E., Damineli, A., Moises, A. P., Blum, R. D., and Conti, P. S., E-mail: navarete@usp.br. THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3. United States: N. p., 2011. Web. doi:10.1088/0004-6256/142/3/67.
Navarete, F., Figueredo, E., Damineli, A., Moises, A. P., Blum, R. D., & Conti, P. S., E-mail: navarete@usp.br. THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3. United States. doi:10.1088/0004-6256/142/3/67.
Navarete, F., Figueredo, E., Damineli, A., Moises, A. P., Blum, R. D., and Conti, P. S., E-mail: navarete@usp.br. Thu . "THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3". United States. doi:10.1088/0004-6256/142/3/67.
@article{osti_21582999,
title = {THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3},
author = {Navarete, F. and Figueredo, E. and Damineli, A. and Moises, A. P. and Blum, R. D. and Conti, P. S., E-mail: navarete@usp.br},
abstractNote = {Spectrophotometric distances in the K band have been reported by different authors for a number of obscured Galactic H II regions. Almost 50% of them show large discrepancies compared to the classical method using radial velocities measured in the radio spectral region. In order to provide a crucial test of both methods, we selected a target that does not present particular difficulty for any method and which has been measured by as many techniques as possible. The W3 star-forming complex, located in the Perseus arm, offers a splendid opportunity for such a task. We used the Near-Infrared Integral Field Spectrograph on the Frederick C. Gillett Gemini North telescope to classify candidate 'naked photosphere' OB stars based on Two Micron All Sky Survey photometry. Two of the targets are revealed to be mid-O-type main-sequence stars leading to a distance of d = 2.20 kpc. This is in excellent agreement with the spectrophotometric distance derived in the optical band (d = 2.18 pc) and with a measurement of the W3 trigonometric parallax (d = 1.95 kpc). Such results confirm that the spectrophotometric distances in the K band are reliable. The radio-derived kinematic distance, on the contrary, gives a distance twice as large (d = 4.2 kpc). This indicates that this region of the Perseus arm does not follow the Galactic rotation curve, and this may also be the case for other H II regions for which discrepancies have been found.},
doi = {10.1088/0004-6256/142/3/67},
journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 3,
volume = 142,
place = {United States},
year = {2011},
month = {9}
}