Credit: ESO, ALMA (ESO/NAOJ/NRAO)/A. Schruba, VLA (NRAO)/Y. Bagetakos/Little THINGS
With their spectacular glowing arms, grand spiral galaxies seem to get all the attention — but NGC 6822, a barred irregular
dwarf galaxy, proves that regular spirals do not have a monopoly on
galactic beauty. Also called Barnard’s galaxy, NGC 6822 is located in
the constellation of Sagittarius just 1.6 million light-years away and is brimming with rich star formation regions.
This new image is a composite of older observations made with the Wide Field Imager attached to the 2.2-metre MPG/ESO telescope at ESO’s La Silla Observatory and new data collected by the Atacama Large Millimeter/submillimeter Array (ALMA). The areas observed with ALMA are highlighted in the image and can be seen here in detail.
The
observations by ALMA reveal the structure of star-forming gas clouds in
unprecedented resolution. Observations in our own galaxy have shown
that stars form in the dense cores of giant clouds of molecular hydrogen
gas, the only places where gas can become cold enough to collapse under
its own gravity. These conditions also foster the formation of other
molecules, such as carbon monoxide, which are an indispensable tool in helping astronomers to detect galactic molecular hydrogen gas.
Until
recently, astronomers have only been able to resolve star formation
regions within the Milky Way — but now ALMA’s sharp sight provides a
window into star formation in other galaxies. The analysis of the data
revealed that, unlike in our own galaxy, the observed molecules are
concentrated into small, dense cores of gas. This explains why it has
been so hard to observe extragalactic star formation regions so far,
especially in low mass, low metallicity galaxies. ALMA also found that
the cores in NGC 6822 behave remarkably similarly to stellar nurseries
in the Milky Way, indicating that the physics of star formation in these
low-mass galaxies resemble that which we see in our own galaxy.
Links
- Star forming gas clouds in NGC 6822
- ALMA observes clouds in NGC 6822
- Barnard’s galaxy seen with the 2.2-metre MPG/ESO telescope
- Research paper by Schruba et al.
- MPE press release
- NOVA press release
Source: ESO/Images
