Prospecting for spiral structure in the flocculent outer milky way disk with color-magnitude star counts from the two micron all sky survey

被引:13
作者
Quillen, AC [1 ]
机构
[1] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA
关键词
galaxy : disk; galaxy : structure;
D O I
10.1086/341379
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Using star counts in both color and magnitude from the Two Micron All Sky Survey Second Incremental Release Point Source Catalog, we search for evidence of large-scale nonuniform extinction and stellar population density changes in the Galactic plane. Extinction causes the entire main sequence to shift toward redder colors on a color-magnitude diagram. A local increase in the stellar density causes an increase in the star counts along a line parallel to the main sequence. We find streaks in star count color-magnitude contour plots along the angle of the main sequence that are likely to be caused by distant gas clouds and stellar density variations. The distance of a gas cloud or stellar density change can be estimated from an adaptation of the Wolf diagram or the location of the shift in the star count contours. We identify features in these diagrams that are coherent across at least 10degrees in Galactic longitude. A series of features is seen at the distance of the expected Perseus spiral arm, 2-4 kpc from the Sun. However, other features as prominent are found at both larger and smaller distances. These structures are over 300 pc in size and so likely to be associated with large-scale coherent structures in the gas distribution such as weak spiral arms. The presence of multiple and weak spiral arms and lack of strong ones suggests that the outer Milky Way is flocculent in its morphology.
引用
收藏
页码:924 / 930
页数:7
相关论文
共 18 条
[1]   Another bar in the Bulge [J].
Alard, C .
ASTRONOMY & ASTROPHYSICS, 2001, 379 (03) :L44-L47
[2]  
[Anonymous], 1953, Statistical astronomy
[3]  
Cambrésy L, 1999, ASTRON ASTROPHYS, V345, P965
[4]   Stellar population studies with the SDSS. I. The vertical distribution of stars in the Milky Way [J].
Chen, B ;
Stoughton, C ;
Smith, JA ;
Uomoto, A ;
Pier, JR ;
Yanny, B ;
Ivezic, Z ;
York, DG ;
Anderson, JE ;
Annis, J ;
Brinkmann, J ;
Csabai, I ;
Fukugita, M ;
Hindsley, R ;
Lupton, R ;
Munn, JA .
ASTROPHYSICAL JOURNAL, 2001, 553 (01) :184-197
[5]  
de Jong R. S., 1996, J ASTRON DATA, V2
[6]   STAR COUNTS AND VISUAL EXTINCTIONS IN DARK NEBULAE [J].
DICKMAN, RL .
ASTRONOMICAL JOURNAL, 1978, 83 (04) :363-372
[7]   Three-dimensional structure of the Milky Way disk:: The distribution of stars and dust beyond 0.35 R⊙ [J].
Drimmel, R ;
Spergel, DN .
ASTROPHYSICAL JOURNAL, 2001, 556 (01) :181-202
[8]   Evolutionary tracks and isochrones for low- and intermediate-mass stars:: From 0.1.5 to 7 M⊙ and from Z=0.0004 to 0.03 [J].
Girardi, L ;
Bressan, A ;
Bertelli, G ;
Chiosi, C .
ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 2000, 141 (03) :371-383
[9]   DUST EXTINCTION AND MOLECULAR GAS IN THE DARK CLOUD IC 5146 [J].
LADA, CJ ;
LADA, EA ;
CLEMENS, DP ;
BALLY, J .
ASTROPHYSICAL JOURNAL, 1994, 429 (02) :694-709
[10]   Mapping the interstellar dust with near-infrared observations: An optimized multi-band technique [J].
Lombardi, M ;
Alves, J .
ASTRONOMY & ASTROPHYSICS, 2001, 377 (03) :1023-1034