EPoS Contribution
EPoS Contribution
Deuterium fraction and kinematics in low mass star forming regions: environmental effects

Anna Punanova
MPE, Garching, DE
We study the earliest stages of star formation in different environments by observing deuterated molecules and by measuring the deuterium fraction. In this work, we focus our deuteration studies on two nearby low-mass star forming regions: the Ophiuchus molecular cloud, the nearest cluster forming region, and the more quiescent Taurus molecular cloud. We measure the deuterium fraction (RD) and CO depletion factor (fd) towards dense cores in L1688 region in Ophiuchus and deuterium fraction along the filamentary structure L1495 in Taurus and search for variations based upon environmental differences across these regions. Also, we discuss the kinematic properties of the dense gas traced by the N2H+ and N2D+ lines in L1688 and L1495. Observations were performed with the IRAM 30-meter telescope. The dense cores in Ophiuchus show large (2-80%) deuterium fractions and moderate CO-depletion factors (1-10). We found that some dense cores show a steep RD-fd correlation, where large values of RD are found in correspondence of low CO freeze-out and relatively quiescent gas. These are probably recently formed centrally concentrated starless cores which have not yet started the contraction phase toward protostellar formation. Most of the cores in Taurus have moderate deuterium fractions (10-25%). The velocity gradient of 0.3-0.5 km/s was found across most of the cores, which shows the possible presence of rotation. We also find that the deuterium fraction in L1688 is affected by the amount of turbulence, dust temperature, dust continuum flux and distance from heating sources. These results will be compared to the results of the same study towards the dense cores in L1495.
Caption: Left: Deuterium fraction as a function of CO depletion factor in L1688. The protostellar cores are depicted with black open circles, different colours show sub-regions A-I, dashed line shows RD-fd correlation from Crapsi et al. 2005. Centre and Right: N2D+(2-1) main component velocity (VLSR) maps of two starless isolated cores in Taurus (centre) and Ophiuchus (right). Contours step is 0.05 km/s. The two velocity maps show significant differences in the internal motions.
P. Caselli, MPE, DE
A. Pon, UWO, CA
J. Pineda, MPE, DE
A. Belloche, MPIfR, DE
P. Andre, CEA, FR
Key publication

Suggested Session: Cores and Collapse