DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H{sub 2}O MASER ASTROMETRY

Journal Article · Mon Sep 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/721/1/267· OSTI ID:21464873

Asaki, Y ^[1]; Deguchi, S ^[2]; Imai, H ^[3]; Hachisuka, K ^[4]; Miyoshi, M ^[5]; Honma, M ^[6]

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1. Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuou, Sagamihara, Kanagawa 252-5210 (Japan)
2. Nobeyama Radio Observatory, Nobeyama, Minamimaki, Minamisaku 384-1305 (Japan)
3. Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan)
4. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China)
5. Division of Radio Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
6. Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

We have conducted Very Long Baseline Array phase-referencing monitoring of H{sub 2}O masers around the red supergiant, S Persei, for six years. We have fitted maser motions to a simple expanding-shell model with a common annual parallax and stellar proper motion, and obtained the annual parallax as 0.413 {+-} 0.017 mas and the stellar proper motion as (-0.49 {+-} 0.23 mas yr{sup -1}, -1.19 {+-} 0.20 mas yr{sup -1}) in right ascension and declination, respectively. The obtained annual parallax corresponds to the trigonometric distance of 2.42{sup +0.11}{sub -0.09} kpc. Assuming a Galactocentric distance of the Sun of 8.5 kpc, the circular rotational velocity of the local standard of rest at a distance of the Sun of 220 km s{sup -1}, and a flat Galactic rotation curve, S Persei is suggested to have a non-circular motion deviating from the Galactic circular rotation for 15 km s{sup -1}, which is mainly dominated by the anti-rotation direction component of 12.9 {+-} 2.9 km s{sup -1}. This red supergiant is thought to belong to the OB association, Per OB1, so that this non-circular motion is representative of a motion of the OB association in the Milky Way. This non-circular motion is somewhat larger than that explained by the standard density-wave theory for a spiral galaxy and is attributed to either a cluster shuffling of the OB association, or to non-linear interactions between non-stationary spiral arms and multi-phase interstellar media. The latter comes from a new view of a spiral arm formation in the Milky Way suggested by recent large N-body/smoothed particle hydrodynamics numerical simulations.

• OSTI ID: 21464873
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 721; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AMPLIFIERS
COMPUTERIZED SIMULATION
DISTANCE
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUID MECHANICS
GALAXIES
HYDRODYNAMICS
HYDROGEN COMPOUNDS
MAIN SEQUENCE STARS
MASERS
MECHANICS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
MILKY WAY
MOTION
OXYGEN COMPOUNDS
PROPER MOTION
ROTATION
SIMULATION
STARS
SUN
WATER