English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We have carried out a survey toward the central regions of 85 starless coresin HCN J = 1-0 to study inward motions in the cores. Sixty-four cores weredetected with HCN lines. The infall asymmetry in the HCN spectra is found to bemore prevalent, and more prominent than in any other previously used infalltracers such as CS J = 2-1, DCO+ J = 2-1, and N2H+ J = 1-0. We found closerelation between the intensities of the HCN and N2H+ lines. This implies thatthe HCN is not much depleted in the central regions of the cores. In somecores, the HCN spectra show different sign of asymmetry from other molecularlines. A few cores show various signs of asymmetry in individual HCN hyperfinelines. The distribution of the velocity shift dV of the HCN profiles withrespect to the systemic velocity of the optically thin tracer is found to bemore shifted toward bluer side than those of other infall tracers, indicatingthat the HCN traces inward motions more frequently. The dV distribution of eachHCN hyperfine line for all sources is similar. Moreover the dV values obtainedfrom different HCN hyperfine lines for each source are nearly similar. Thesemay mean that most of starless cores are in similar kinematic states across thelayers of the cores. We identify 17 infall candidates using all availableindicators such as the velocity shift dV and the blue to red peak intensityratio of double peaked profiles for HCN J = 1-0, CS J = 2-1, J = 3-2, DCO+ J =2-1, and N2H+ J = 1-0. Four of them, L63, L492, L694-2, and L1197 are found toshow higher blue to red ratio in the HCN hyperfine line along the loweropacity, suggesting that infall speed becomes higher toward the center.

Probing Inward Motions in Starless Cores Using The HCN J = 1-0 Hyperfine Transitions : A Pointing Survey Toward Central Regions