A Possible Extension of the Scutum-Centaurus Arm into the Outer Second Quadrant
| Autor: | Xin Zhou, Ji Yang, Xinyu Du, Fa Cheng Li, Yan Sun, Ye Xu, Shaobo Zhang |
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| Rok vydání: | 2014 |
| Předmět: |
Physics
Spiral galaxy Milky Way Molecular cloud Galactic quadrant FOS: Physical sciences Astronomy and Astrophysics Astrophysics Quadrant (instrument) Galactic plane Astrophysics - Astrophysics of Galaxies Space and Planetary Science Scutum–Centaurus Arm Astrophysics of Galaxies (astro-ph.GA) Pitch angle |
| DOI: | 10.48550/arxiv.1412.2425 |
| Popis: | Combining HI data from the Canadian Galactic Plane Survey~(CGPS) and CO data from the Milky Way Imaging Scroll Painting (MWISP) project, we have identified a new segment of a spiral arm between Galactocentric radii of 15 and 19~kpc that apparently lies beyond the Outer Arm in the second Galactic quadrant. Over most of its length, the arm is 400-600 pc thick in $z$. The new arm appears to be the extension of the distant arm recently discovered by Dame & Thaddeus (2011) as well as the Scutum-Centaurus Arm into the outer second quadrant. Our current survey identified a total of 72 molecular clouds with masses on the order of 10$^2$-10$^4$M$_{\sun}$ that probably lie in the new arm. When all of the available data from the CO molecular clouds are fit, the best$-$fitting spiral model gives a pitch angle of 9.3$^{\circ}$ $\pm$0.7$^{\circ}$. 11 pages, 3 figures; Accepted for publication in ApJ Letters |
| Databáze: | OpenAIRE |
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