Forest of Molecular Signals in Star Forming Galaxy
Overview of the press release
Astronomers found a rich molecular reservoir in the heart of an active star-forming galaxy with the Atacama Large Millimeter/submillimeter Array (ALMA). Among eight clouds identified at the center of the galaxy NGC 253, one exhibits very complex chemical composition, while in the other clouds many signals are missing. This chemical richness and diversity shed light on the nature of the baby boom galaxy.
Ryo Ando, a graduate student of the University of Tokyo, and his colleagues observed the galaxy NGC 253 and for the first time, they resolved the locations of star formation in this galaxy down to the scale of a molecular cloud, which is a star formation site with a size of about 30 light-years. As a result, they identified eight massive, dusty clouds aligned along the center of the galaxy.
“With its unprecedented resolution and sensitivity, ALMA showed us the detailed structure of the clouds,” said Ando, the lead author of the research paper published in the Astrophysical Journal. “To my surprise, the gas clouds have a strong chemical individuality despite their similarity in size and mass.”
Different molecules emit radio waves at different frequencies. Using this feature, the team investigated the chemical composition of the distant clouds by analyzing the radio signals precisely. They identified signals from various molecules including formaldehyde (H2CO), hydrogen cyanide (HCN), and many organic molecules.
Figure: The starburst galaxy NGC 253 and the radio spectra obtained with ALMA. ALMA detected radio signals from 19 different molecules at the center of this galaxy.
Credit: ESO/J. Emerson/VISTA, ALMA (ESO/NAOJ/NRAO), Ando et al. Acknowledgment: Cambridge Astronomical Survey Unit
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