Astronomers see mysterious nitrogen area in a butterfly-shaped star formation disk

An international team of astronomers, led by Dutch
scientists, has discovered a region in our Milky Way that
contains many nitrogen compounds in the southeast of a
butterfly-shaped star formation disk and very little in the
north-west. This artistic impression shows the universe around
the star formation area with, as an overlay, the scientists’
observations. Credit: Veronica Allen/Alexandra Elconin

An international team of astronomers, led by Dutch
scientists, has discovered a region in our Milky Way that
contains many nitrogen compounds in the southeast of a
butterfly-shaped star formation disk and very little in the
north-west. The astronomers suspect that multiple stars-to-be
share the same star formation disk, but the precise process
is still a puzzle. The article with their findings has been
accepted for publication in Astronomy & Astrophysics.

An international team of astronomers studied the star forming
region G35.20-0.74N, more than 7000 light years from Earth in
the southern sky. The astronomers used the (sub)millimeter
telescope ALMA that is based on the Chilean Chajnantor plateau.
ALMA can map molecular gas clouds in which stars form.

The researchers saw something special in the disk around a
young, heavy star. While large amounts of oxygen-containing and
sulfur-containing hydrocarbons were present throughout the
disk, the astronomers found only nitrogen-containing molecules
in the southeastern part of the disk. In addition, it was 150
degrees warmer on the nitrogen side than on the other side of
the disk.

Based on these observations, the scientists suspect that there
are multiple stars forming at the same time in one disk and
that some stars are hotter or heavier than others. The
researchers expect the disk to eventually break into several
smaller disks as the grow.

A few years ago, there have been observed chemical differences
in a star forming region in Orion. First author Veronica Allen
(University of Groningen and SRON): “The area in Orion is five
times bigger than our area. We have probably been lucky because
we expect that such a chemical difference to be short-lived.”

Second author Floris van der Tak (University of Groningen and
SRON): “Many of the nitrogen molecules are poisonous cyanides.
We do not know much about them because it is dangerous to work
with those molecules in laboratories on earth.”

The astronomers are now investigating the star formation cloud
in more detail. Allen: “Maybe we can see the break into smaller disks in real time.” In
addition, the astronomers make models to see how differences in
age, mass, temperature or gas density can cause a difference in
chemical composition, too.

Explore further:

First radio detection of lonely planet disk shows similarities
between stars and planet-like objects

More information: V. Allen et al. Chemical segregation
in hot cores with disk candidates. An investigation with ALMA,
Astronomy & Astrophysics (2017). DOI: 10.1051/0004-6361/201629118

Journal reference: Astronomy
& Astrophysics