Copyright: ESA/XMM-Newton (X-rays); MPG/ESO (optical); NASA/Spitzer (infrared)
Acknowledgement: S. Carpano, Max-Planck Institute for Extraterrestrial Physics
This swirling palette of colours portrays the life cycle of stars in a spiral galaxy known as NGC 300.
Located some six million light-years away, NGC 300 is relatively nearby. It is one of the closest galaxies beyond the Local Group – the hub of galaxies to which our own Milky Way galaxy belongs. Due to its proximity, it is a favourite target for astronomers to study stellar processes in spiral galaxies.
The population of stars in their prime is shown in this
image in green hues, based on optical observations performed with the
Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope
at La Silla, Chile. Red colours indicate the glow of cosmic dust in the
interstellar medium that pervades the galaxy: this information derives
from infrared observations made with NASA’s Spitzer space telescope, and can be used to trace stellar nurseries and future stellar generations across NGC 300.
A complementary perspective on this galaxy’s composition comes from data collected in X-rays by ESA’s XMM-Newton
space observatory, shown in blue. These represent the end points of the
stellar life cycle, including massive stars on the verge of blasting
out as supernovas, remnants of supernova explosions, neutron stars, and
black holes. Many of these X-ray sources are located in NGC 300, while
others – especially towards the edges of the image – are foreground
objects in our own Galaxy, or background galaxies even farther away.
The
sizeable blue blob immediately to the left of the galaxy’s centre is
especially interesting, featuring two intriguing sources that are part
of NGC 300 and shine brightly in X-rays.
One of them, known as NGC 300 X-1, is in fact a binary system, consisting of a Wolf-Rayet star – an ageing hot, massive and luminous type star that drives strong winds into its surroundings – and a black hole, the compact remains of what was once another massive, hot star. As matter from the star flows towards the black hole, it is heated up to temperatures of millions of degrees or more, causing it to shine in X-rays.
The other source,
dubbed NGC 300 ULX1, was originally identified as a supernova explosion
in 2010. However, later observations prompted astronomers to reconsider
this interpretation, indicating that this source also conceals a binary
system comprising a very massive star and a compact object – a neutron
star or a black hole – feeding on material from its stellar companion.
Data
obtained in 2016 with ESA’s XMM-Newton and NASA’s NuSTAR observatories
revealed regular variations in the X-ray signal of NGC 300 ULX1,
suggesting that the compact object in this binary system is a highly
magnetized, rapidly spinning neutron star, or pulsar.
The large
blue blob in the upper left corner is a much more distant object: a
cluster of galaxies more than one billion light years away, whose X-ray
glow is caused by the hot diffuse gas interspersed between the galaxies.
Explore NGC 300 in ESASky
Source: ESA/Space Images
