Sublimation of Organic Molecules in a Space Hamburger

Released: 7th Oct., 2022, Academia Sinica, Institute of Astronomy & Astrophysics (ASIAA), Taiwan

Organic molecules are detected in the gas phase at the planet-formation scale in the accretion disk (Space Hamburger) in the HH 212 star-forming system, which lies at about 1300 light-year away in the constellation of Orion. Some are prebiotic and thus may shed light on how life came to be on Earth and if extraterrestrial life can be formed in space.

In particular, an international research team, led by Chin-Fei Lee at Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), has observed six molecules (formaldehyde H2CO, methanol CH3OH, formamide NH2CHO, formic acid HCOOH, acetaldehyde CH3CHO, and isocyanic acid HNCO) using the Atacama Large Millimeter/submillimeter Array (ALMA). The observations at an unprecedented spatial resolution (around 10 au) unveil for the first time the stratified distribution of these molecules . More importantly, the distribution of H2CO, CH3OH, NH2CHO, and HCOOH is consistent with the distribution of their sublimation temperature, supporting that they sublimate into the gas phase from the ice mantle of dust grains in the disk into the disk atmosphere.

“Thanks to the powerful ALMA, we finally can differentiate the distribution of organic molecules in the disk atmosphere. We find that a molecule with a lower sublimation temperature starts to appear at a larger radius where the temperature is lower. This behavior supports that molecules must be originally stored in the ice mantle of dust grains in the disk and then sublimate into the gas phase by the heat”, said the lead author Chin-Fei Lee.

Claudio Codella, the 2nd author of the paper commented that “NH2CHO is a prebiotic molecule and thought to be formed from HNCO in ice mantle or H2CO in gas phase. However, our result appears to rule out the first formation path and challenge the second formation path. Further work is thus still needed to determine the formation path of this molecule in the disk.”

“Some of these molecules, e.g., H2CO and CH3OH, are likely originally formed in the ice mantle on dust grains much earlier in the pre-stellar core and then brought in to the disk by the gravitational collapse. ” added Cecelia Ceccarelli, the 3rd author of the paper.

More Information:

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organization for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

This research was presented in a paper “Stratified Distribution of Organic Molecules at the Planet-formation Scale in the HH 212 Disk Atmosphere” by Lee et al. appeared in Astrophysical Journal.

The team is composed of Chin-Fei Lee (ASIAA, Taiwan; National Taiwan University, Taiwan), Claudio Codella (INAF, Italy; Univ. Grenoble Alpes, CNRS, IPAG, France) , Cecilia Ceccarelli (Univ. Grenoble Alpes, CNRS, IPAG, France) , and Ana López-Sepulcre (IRAM, France)

Media Contact:

Dr. Chin-Fei Lee, Email: cflee@asiaa.sinica.edu.tw, Tel: +886 2 2366 5445