A particular carbon-chain-producing region: L1489 starless core

Abstract

We detected carbon-chain molecules (CCMs) HC 2n+1 N (n=1-3) and C 3 S in K u band as well as high-energy excitation lines including C 4 H N=9-8, J=17/2-15/2, 19/2-17/2, and CH 3 CCH J=5-4, K=2 in the 3 mm band toward a starless core called the eastern molecular core (EMC) of L1489 IRS. Maps of all the observed lines were also obtained. Comparisons with a number of early starless cores and WCCC source L1527 show that the column densities of C 4 H and CH 3 CCH are close to those of L1527, and the CH 3 CCH column densities of the EMC and L1527 are slightly higher than those of TMC-1. The EMC and L1527 have similar C 3 S column densities, but they are much lower than those of all the starless cores, with only 6.5% and 10% of the TMC-1 value, respectively. The emissions of the N-bearing species of the EMC and L1527 are at the medium level of the starless cores. These comparisons show that the CCM emissions in the EMC are similar to those of L1527, though L1527 contains a protostar. Although dark and quiescent, the EMC is warmer and at a later evolutionary stage than classical carbon-chain-producing regions in the cold, dark, quiescent early phase. The PACS, SPIRE, and SCUBA maps evidently show that the L1489 IRS seems to be the heating source of the EMC. Although it is located at the margins of the EMC, its bolometric luminosity and bolometric temperature are relatively high. Above all, the EMC is a rather particular carbon-chain-producing region and is quite significant for CCM science.

Which Part of Dense Cores Feeds Material to Protostars?: The Case of L1489 IRS

“…The continuum emission is extended to the northeast from the center and shows the second peak at the east side of the protostar. This second peak originates within a starless core near the protostar, as reported in previous observations (Hogerheijde & Sandell 2000;Motte & André 2001;Wu et al 2019). The C 18 O emission exhibits a peak at the protostellar position and it thus likely traces an envelope associated with the protostar.…”

“…The extended emissions at LSR velocities of 6.62-6.96 km s −1 appears to be associated with the C 18 O secondary peak seen in the moment 0 map because they show stronger peaks at the C 18 O secondary peak position. The molecular emissions associated with L1489 starless core show their peaks at LSR velocities of ∼6.6-6.8 km s −1 (Caselli et al 2002a;Wu et al 2019), suggesting that the extended emission is also a part of the starless core. Figure 3 shows a position-velocity (PV) diagram cut along the direction of the disk major axis (P.A.= 54°; Sai et al 2020) to investigate the velocity gradient of the C 18 O emission in more detail.…”

“…In this paper, we have examined a SMFZ around the Class I protostar L1489 IRS as a case study. L1489 IRS is relatively isolated in the Taurus molecular cloud (d∼140 pc; Zucker et al 2019) and located close to the western edge of the dense core L1489 (Benson & Myers 1989;Hogerheijde & Sandell 2000;Motte & André 2001;Wu et al 2019). The object is considered to be a late Class I protostar according to the bolometric temperature and luminosity of 226 K and 3.5 L , respectively (Green et al 2013).…”

A search for cloud cores affected by shocked carbon chain chemistry in L1251

“…These lines were detected towards ten of the eleven observed sources. Three sources, IRAS 20582+7724 (I20582), L1221 and L1251A (corresponding to IRS3 in the L1251-A region, hereafter L1251-IRS3), were explained in terms of a new chemical mechanism -shocked carbon chain chemistry (SCCC); another outflow source, the eastern molecular core of the outflow source L1489 (L1489 EMC) was identified as a particular carbon-chain production region and as a candidate of a WCCC source (Wu et al 2019b).…”

“…Red and gray points show the data for SCCC sources and early carbon-chain cores (ECCC) fromWu et al (2019a), detected in Ku band. Black points represent WCCC sources Lupus I-1 ((Sakai et al 2009; Wu et al 2019a, IRAS 15398-3359)) and L1489 EMC(Wu et al 2019b).…”