Skip to main content

Forest of Molecular Signals in Star Forming Galaxy

Spiral Galaxy NGC 253. Credit: ESO

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.

 One of the clouds stood out with its extremely rich chemical composition. The team identified footprints of 19 different molecules in the cloud, such as thioformaldehyde (H2CS), propyne (CH3CCH), and complex organic molecules including methanol (CH3OH) and acetic acid (CH3COOH). “The data are filled with the signals of various molecules,” said Ando. “It is like a forest of molecules.”

 Many “molecular forests” have been found in our Milky Way Galaxy, but this is the first example outside the Milky Way. Researchers assume that the molecular jungle is an aggregate of dense and warm cocoons around bright baby stars. The cocoon gas is heated from inside by hundreds of young stars and a myriad of chemical reactions is driven to form various molecules.
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



Interestingly, the number of chemical signals is different in different clouds. For example, another cloud among the eight has a very sparse chemical composition, even though it is located within dozens of light-years of the chemically rich cloud. Such a diverse nature of star forming clouds has never been seen before and could be a key to understanding the starburst process in this galaxy.

 NGC 253 is a prototypical active star forming galaxy, or starburst galaxy. It is located 11 million light-years away in the constellation Sculptor. Starburst, or baby boom, galaxies have been the major drivers of star formation and galaxy evolution throughout the whole history of the Universe. Therefore it is crucial to understand what exactly is going on in the heart of such galaxies.

Text Credit


 ALMA

Resources


 Forest of Molecular Signals in Star Forming Galaxy

Next Post


ALMA Discovers Cold Dust Around Nearest Star

Etichette:

Comments

Post a Comment

Popular posts from this blog

GAMMA-RAY EMISSION FROM THE SNR HB3

Image: At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded. Credit: NASA/CXC/SAO The processes of particles acceleration to very high energies from the supernova shock region and diffusion in the interstellar medium of such particles has not been well understood so far. Gamma-ray observations in the GeV regime are a powerful probe of these mechanisms
Post a Comment
Read more

THE HITCHCHIKER'S GUIDE TO THE LOCAL SUPERCLUSTER

Image: Virgo Supercluster. Credit: Andrew Z. Colvin The Virgo Supercluster is a region with a diameter of 33 megaparsecs (~1000 times larger the Milky Way's diameter) containing at least 100 galaxy groups and clusters.
Post a Comment
Read more

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).
Post a Comment
Read more