# Digging into the Interior of Hot Cores with ALMA (DIHCA). VII. Disk candidates around high-mass stars and evidence of anisotropic infall

**Authors:** Fernando A. Olguin, Patricio Sanhueza, Yoko Oya, Adam Ginsburg, Maria T. Beltrán, Kaho Morii, Roberto Galván-Madrid, Huei-Ru Vivien Chen, Qiuyi Luo, Kei E. I. Tanaka, Suinan Zhang, Yu Cheng, Fumitaka Nakamura, Shanghuo Li, Kotomi Taniguchi, Guido Garay, Qizhou Zhang, Masao Saito, Takeshi Sakai, Xing Lu  
**arXiv:** [2601.15371](https://arxiv.org/abs/2601.15371)  
**Date:** 2026-01-21  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2601.15371v1/

## Key points

- Study conducted by Fernando A. Olguin et al. investigates kinematics of condensations in 30 fields where high-mass stars are forming using ALMA at high resolution.
- Presence of disks crucial for sustaining growth of high-mass stars without feedback mechanisms impeding their development.
- Gas tracers such as CH$_3$OH, CH$_3$CN, HNCO, and cis-HCOOH used to analyze velocity distributions showing gradients suggestive of rotational motion.
- Total of 32 disk candidates identified, representing largest sample uniformly analyzed at scales within a few hundred astronomical units in high-mass star formation regime.
- Position-velocity maps exhibit asymmetry with one side brighter than the other; power law indices range from -0.5 to -1 with median index value of -0.7.
- Estimated central masses for disk candidates range between 7 to 45 solar masses; most disk candidates relatively more compact and less massive compared to previous findings at lower resolutions.
- Most disk candidates found to be gravitationally unstable based on Toomre-$Q$ parameters with median value of 0.5.
- Observations provide opportunity to distinguish between disk and envelope components within hot cores on statistically relevant sample size; anisotropic collapse plays crucial role in supplying material during formation process.

## Summary

, , , , 

The study "Digging into the Interior of Hot Cores with ALMA (DIHCA). VII: Disk candidates around high-mass stars and evidence of anisotropic infall," conducted by Fernando A. Olguin et al., investigates the kinematics of condensations in 30 fields where high-mass stars are forming using the Atacama Large Millimeter/submillimeter Array (ALMA) at a high resolution of approximately 0.08'' (~230 au). The presence of disks is crucial for sustaining the growth of high-mass stars without feedback mechanisms impeding their development as their masses increase. The research focuses on identifying velocity gradients resembling rotation that can indicate the presence of disks around these high-mass stars. Through analyzing gas tracers such as CH$_3$OH, CH$_3$CN, and tentative detections of HNCO and cis-HCOOH in 49 objects, the team uncovers velocity distributions showing gradients suggestive of rotational motion. They identify a total of 32 disk candidates, representing the largest sample to date that has been uniformly analyzed at scales within a few hundred astronomical units in the high-mass star formation regime. Position-velocity maps of these disk candidates exhibit asymmetry, with one side appearing brighter than the other. By fitting power laws to these maps, indices ranging from -0.5 (indicative of Keplerian rotation) to -1 (suggesting rotation under specific angular momentum conservation) are found, with a median index value of -0.7. Assuming Keplerian rotation, central masses for these disk candidates are estimated to range between 7 to 45 solar masses, although these values are not corrected for inclination. Excluding outliers, it is observed that the disk candidates tend to be relatively more compact (<200 au) and less massive (<5 solar masses) compared to previous findings at lower angular resolutions. Calculations based on Toomre-$Q$ parameters reveal that most disk candidates are gravitationally unstable, with a median value of 0.5. The study concludes by emphasizing that these observations provide a significant opportunity to distinguish between the disk and envelope components within hot cores on a statistically relevant sample size. Furthermore, it confirms that anisotropic collapse plays a crucial role in supplying material to feed high-mass (proto)stars during their formation process.