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The ALMA-QUARKS survey: Evidence of a candidate high-mass prestellar core aside a bright-rimmed cloud IRAS 18290-0924

Dongting Yang, Hong-Li Liu, Shengli Qin, Tie Liu, Anandmayee Tej, Siju Zhang, Xunchuan Liu, Fengwei Xu, Guido Garay, Lei Zhu, Patricio Sanhueza, Xiaofeng Mai, Wenyu Jiao, Paul F. Goldsmith, Sami Dib, Pablo Garcıa, Di Li, Jinhua He, A. Y. Yang, Prasanta Gorai, Suinan Zhang, Yankun Zhang, Jianjun Zhou, Mika Juvela, James O. Chibueze, Chang Won Lee, Jihye Hwang, Leonardo Bronfman, Xindi Tang, Archana Soam, Tapas Baug, Yichen Zhang, Swagat Ranjan Das, L. K. Dewangan, L. Viktor Toth

TL;DR

This study uses ALMA ATOMS and QUARKS two-band data to analyze the C2 core in the bright-rimmed cloud IRAS 18290-0924 as a test for a high-mass prestellar core. It finds a massive, largely unfragmented core with $M_{ m core} \approx 27$–$68\,M_{\odot}$ and a single central condensation of $M_{\rm cond} \approx 19\,M_{\odot}$ at $R \approx 400$ au, with no outflows or embedded YSOs. Virial analysis yields $\alpha_{\rm vir} \sim 0.1$–$0.3$, suggesting subvirial, magnetically influenced stability that could permit collapse without fragmentation. The results provide rare empirical support for high-mass prestellar cores and emphasize the importance of broad molecular-line surveys and future chemical diagnostics (e.g., deuterated species) to confirm the evolutionary state.

Abstract

Although frequently reported in observations, the definitive confirmation of high-mass prestellar cores has remained elusive, presenting a persistent challenge in star formation studies. Using two-band observational data from the 3mm ATOMS and 1.3mm QUARKS surveys, we report a high-mass prestellar core candidate, C2, located on the side of the bright-rimmed cloud IRAS 18290-0924. The C2 core identified from the 3mm continuum data of the ATOMS survey ($\sim$2 arcsecond, $\rm\sim 10000~au$ at 5.3 kpc) has a mass ranging from 27-68 $M_{\odot}$ for temperatures 10-22K within a radius of $\sim$2800 au. The highest-resolution ($\sim$0.3 arcsecond, $\rm\sim 1500 au$) observations of this source presented to date from the QUARKS survey reveal no evidence of further fragmentation. Further analysis of a total $\sim$10 GHz band width of molecular line survey does not find star-formation activity (e.g., outflows, ionized gas) associated with the core, with a few molecular lines of cold gas detected only. Additionally, virial analysis indicates the C2 core is gravitationally bound ($α_{\rm vir} \sim0.1-0.3$) and thus could be undergoing collapse toward star formation. These results strongly establish a candidate for a high-mass prestellar core, contributing to the very limited number of such sources known to date.

The ALMA-QUARKS survey: Evidence of a candidate high-mass prestellar core aside a bright-rimmed cloud IRAS 18290-0924

TL;DR

This study uses ALMA ATOMS and QUARKS two-band data to analyze the C2 core in the bright-rimmed cloud IRAS 18290-0924 as a test for a high-mass prestellar core. It finds a massive, largely unfragmented core with – and a single central condensation of at au, with no outflows or embedded YSOs. Virial analysis yields –, suggesting subvirial, magnetically influenced stability that could permit collapse without fragmentation. The results provide rare empirical support for high-mass prestellar cores and emphasize the importance of broad molecular-line surveys and future chemical diagnostics (e.g., deuterated species) to confirm the evolutionary state.

Abstract

Although frequently reported in observations, the definitive confirmation of high-mass prestellar cores has remained elusive, presenting a persistent challenge in star formation studies. Using two-band observational data from the 3mm ATOMS and 1.3mm QUARKS surveys, we report a high-mass prestellar core candidate, C2, located on the side of the bright-rimmed cloud IRAS 18290-0924. The C2 core identified from the 3mm continuum data of the ATOMS survey (2 arcsecond, at 5.3 kpc) has a mass ranging from 27-68 for temperatures 10-22K within a radius of 2800 au. The highest-resolution (0.3 arcsecond, ) observations of this source presented to date from the QUARKS survey reveal no evidence of further fragmentation. Further analysis of a total 10 GHz band width of molecular line survey does not find star-formation activity (e.g., outflows, ionized gas) associated with the core, with a few molecular lines of cold gas detected only. Additionally, virial analysis indicates the C2 core is gravitationally bound () and thus could be undergoing collapse toward star formation. These results strongly establish a candidate for a high-mass prestellar core, contributing to the very limited number of such sources known to date.

Paper Structure

This paper contains 7 sections, 2 equations, 4 figures.

Table of Contents

  1. Introduction
  2. Observations
  3. Results
  4. Parameter estimation of core and condesation
  5. Evolutionary stage of the C2 Core
  6. Dynamical stability of C2 Core and condensation
  7. Discussion and conclusions

Figures (4)

  • Figure 1: Three-colour image of Spitzer 8 $\mu$m (red), 4.5 $\mu$m (green), and 3.6 $\mu$m (blue) of the region associated with I18290. The black contours represent the 1.28 GHz MeerKAT emission. The white and green dashed circles show the FoV of the ATOMS and QUARKS survey, respectively. ATOMS 3 mm dust continuum emission is shown as the cyan contours, with levels starting at 3 $\sigma_{\rm 3\,mm}$ ($\rm\sim 0.1mJy~beam^{-1}$) and increasing as $[6, 12, 24, 48]\times \sigma_{\rm 3\,mm}$. The purple cross symbol shows the location of Core 2 2023MNRAS.520..322Z. The synthesized beam size of the ATOMS survey and the 0.5 pc scale bar are shown in the lower left corner and upper right corner, respectively.
  • Figure 2: QUARKS 1.3 mm dust continuum image (color scale) overlaid with ATOMS 3 mm dust continuum emission (in gray dashed contours, identical to those in Figure \ref{['fig:RGB']}). The black contours are at levels of [3, 6, 12, 24, 48] $\times \sigma_{\rm 1.3\,mm}$, with $\sigma_{\rm 1.3\,mm}\sim0.14\rm mJy~beam^{-1}$. The blue ellipses correspond to the FWHM sizes of the C2 core estimated from the ATOMS 3 mm image using the task CASA imfit. The synthesized beam sizes of the QUARKS and ATOMS survey are shown in the left and right bottom (panel a), respectively. The 0.01 pc scale bar is shown in the upper right corner. Panel (a): CO (2--1) outflow is overlaid on the QUARKS 1.3 mm dust continuum map. The blue and red contour levels are [3, 6, 12, 24, 48] $\times \sigma_{\rm co}$, with $\sigma_{\rm co} \sim\rm 0.08~Jy~beam^{-1}~km~s^{-1}$ for the blue lobes and $\sim\rm 0.06~Jy~beam^{-1}~km~s^{-1}$ for the red lobes. The corresponding velocity ranges are plus/minus $\rm ~5-30~km~s^{-1}$ relative to $\rm V_{LSR}$ ($\sim\rm 84.5~km~s^{-1}$) of the C2 core. Panel (b): zoom-in view of the C2 core. The black ellipses correspond to the FWHM sizes of the condensation estimated from the QUARKS 1.3 mm image using the task casa imfit.
  • Figure 3: Average spectra of the C2 core/condensation. (a): average spectra extracted from two ATOMS wideband SPWs over the C2 core. (b): Same as panel a but for four QUARKS SPWs over the C2 condensation. (c): zoom-in view of the molecular lines detected in the six SPWs (corresponding to panels a and b). The dashed line indicates the systemic velocity of the C2 core ($\rm\sim 84.5\,km\, s^{-1}$). Note that the absorption dips present in both $^{13}$CO and CO spectra are artifacts arising from the missing flux by ALMA, which will be addressed for future more in-depth studies by combining our QUARKS data with new single-dish observations.
  • Figure 4: Average spectra of $\rm H^{13}CO^+$ from the ATOMS survey and average spectra of $\rm N_2D^+$ from the QUARKS survey.