Astronomers have mapped mysterious clouds of high-velocity hydrogen swirling around the Milky Way and other nearby galaxies.
Experts say the local universe is home to ‘curious’ clouds of neutral hydrogen gas, with the material covering up to 13 percent of the sky.
These clouds, however, are known to be moving at different speeds than that of the normal rotation of the Milky Way.
Astronomers have mapped mysterious clouds of high-velocity hydrogen swirling around the Milky Way and other nearby galaxies. Experts say the local universe is home to ‘curious’ clouds of neutral hydrogen gas, with the material accounting for up to 13 percent of the sky
‘These gas clouds are moving towards or away from us at speeds of up to a few hundred kilometers per second,’ said Dr Tobias Westmeier, from the University of Western Australia branch of the International Centre for Radio Astronomy Research.
‘They are clearly separate objects.’
To map the mysterious phenomenon, the team used data from the HI4PI survey of the entire sky, which combined observations from CSIRO’s Parkes Observatory in Australia and the Effelsberg 100m Radio Telescope operated by the Max-Planck Institute for Radio Astronomy in Germany.
Then, they omitted the gas that is moving at the same rate as the Milky Way, revealing the outliers.
In the highest resolution all-sky map of the features yet, the researchers have revealed this neutral hydrogen gas in stunning new detail.
The study has uncovered filaments, branches, and clumps within the clouds that have never been seen before.
These clouds are known to be moving at different speeds than that of the normal rotation of the Milky Way. Despite their prevalence in our own galaxy and at least two nearby, much remains a mystery about these gas clouds, the researcher explains
WHAT IS THE LARGE MAGELLANIC CLOUD?
The Large Magellanic Cloud (LMC) is a nearby galaxy, and a satellite of the Milky Way.
The very first recorded mention of the Large Magellanic Cloud was by Persian astronomer Shirazi, in his Book of Fixed Stars around 964 AD.
It is the third closest galaxy to the Milky Way. Vast clouds of gas within it slowly collapse to form new stars.
The LMC has a diameter of about 14,000 light-years and a mass of approximately 10 billion suns, making it roughly 1/100 as massive as the Milky Way.
The LMC is the fourth largest galaxy in the Local Group, after the Andromeda Galaxy (M31), the Milky Way, and the Triangulum Galaxy (M33).
The LMC is ablaze with star-forming regions.
From the Tarantula Nebula, the brightest stellar nursery in our cosmic neighborhood, to LHA 120-N 11, the small and irregular galaxy is scattered with glowing nebulae, the most noticeable sign that new stars are being born.
It is visible as a faint ‘cloud’ in the night sky of the southern hemisphere straddling the border between the constellations of Dorado and Mensa, and it appears from Earth more than 20 times the width of the full moon.
‘Starting to see all that structure within these high-velocity clouds is very exciting,’ said Dr Westmeier.
‘It’s something that wasn’t really visible in the past, and it could provide new clues about the origin of these clouds and the physical conditions within them.’
Despite their prevalence in our own galaxy and at least two nearby, much remains a mystery about these gas clouds, the researcher explains.
‘We know for certain the origin of one of the long trails of gas, known as the Magellanic Stream, because it seems to be connected to the Large and Small Magellanic Clouds,’ said Dr Westmeier.
‘But all the rest, the origin is unknown.’
The new study shows the clouds in unprecedented detail.
The image above compares the high-velocity neutral hydrogen gas detected by the Leiden/Argentine/Bonn (LAB) survey and the new HI4PI survey for the same region of the sky. The new effort has revealed unprecedented detail
Not long ago, scientists did not know the distances to these high-velocity clouds.
The team has made the map freely available, to help improve understanding on the phenomena.
‘We now know that the clouds are very close to the Milky Way, within about 30,000 light years of the disc,’ said Dr Westmeier.
‘That means it’s likely to either be gas that is falling into the Milky Way or outflows from the Milky Way itself.
‘For example, if there is star formation or a supernova explosion it could push gas high above the disc.’