تقرير
An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud: II CCS & HC$_7$N Chemistry and Three Modes of Star Formation in the Filaments
| العنوان: | An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud: II CCS & HC$_7$N Chemistry and Three Modes of Star Formation in the Filaments |
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| المؤلفون: | Seo, Young Min, Majumdar, Liton, Goldsmith, Paul F., Shirley, Yancy L., Willacy, Karen, Ward-Thompson, Derek, Friesen, Rachel, Frayer, David, Church, Sarah E., Chung, Dongwoo, Cleary, Kieran, Cunningham, Nichol, Devaraj, Kiruthika, Egan, Dennis, Gaier, Todd, Gawande, Rohit, Gundersen, Joshua O., Harris, Andrew I., Kangaslahti, Pekka, Readhead, Anthony C. S., Samoska, Lorene, Sieth, Matthew, Stennes, Michael, Voll, Patricia, White, Steve |
| سنة النشر: | 2018 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies |
| الوصف: | We present deep CCS and HC$_7$N observations of the L1495-B218 filaments in the Taurus molecular cloud obtained using the K-band focal plane array on the 100m Green Bank Telescope. We observed the L1495-B218 filaments in CCS $J_N$ = 2$_1$$-$1$_0$ and HC$_7$N $J$ = 21$-$20 with a spectral resolution of 0.038 km s$^{-1}$ and an angular resolution of 31$''$. We observed strong CCS emission in both evolved and young regions and weak emission in two evolved regions. HC$_7$N emission is observed only in L1495A-N and L1521D. We find that CCS and HC$_7$N intensity peaks do not coincide with NH$_3$ or dust continuum intensity peaks. We also find that the fractional abundance of CCS does not show a clear correlation with the dynamical evolutionary stage of dense cores. Our findings and chemical modeling indicate that the fractional abundances of CCS and HC$_7$N are sensitive to the initial gas-phase C/O ratio, and they are good tracers of young condensed gas only when the initial C/O is close to solar value. Kinematic analysis using multiple lines including NH$_3$, HC$_7$N, CCS, CO, HCN, \& HCO$^+$ suggests that there may be three different star formation modes in the L1495-B218 filaments. At the hub of the filaments, L1495A/B7N has formed a stellar cluster with large-scale inward flows (fast mode), while L1521D, a core embedded in a filament, is slowly contracting due to its self-gravity (slow mode). There is also one isolated core that appears to be marginally stable and may undergo quasi-static evolution (isolated mode). Comment: ApJ accepted |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-4357/aaf887 |
| URL الوصول: | http://arxiv.org/abs/1812.06121 |
| رقم الأكسشن: | edsarx.1812.06121 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-4357/aaf887 |
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