Orion’s Dust Hula Hoop | Markus Bauer

Orion's Dust Hula Hoop | Markus Bauer
Orion’s Dust Hula Hoop | Markus Bauer

The Orion nebula complex is a huge star-forming region of dust and gas about 1350 light years from Earth. It is centred on the famous constellation, but covers areas outside it as well. Eddie Schlafly of the Max Planck Institute for Astronomy in Heidelberg, Germany, and his colleagues used observations and 3D analysis techniques to get a more detailed view of the dust in this region.

The group analysed the colours of some 23 million stars in a roughly 1,000-square-degree region of sky in the Orion constellation in order to measure the temperature and brightness of the stars, which reveals their distances from us.

Intervening dust can redden stars’ colours, so by comparing the distances, colours and brightnesses of those stars, the team could work out when dust lay between the stars and Earth or when it lay beyond the stars. “We’re using all those stars simultaneously to figure out how much dust there is close, how much dust there is at the distance to Orion, and how much dust there is farther away,” says Schlafly.

This technique allowed them to create a 3D map of the region, and a pattern stood out: a dust ring some 330 light years wide that includes the major star-forming regions in Orion.

The team thinks that massive stars, which spew enormous amounts of energy, carved a giant bubble in the region’s gas and dust, pushing dust to the edge of that bubble to appear as a ring. These stars drained their energy reserves in just 10 to 15 million years and have since burned out.

To test that idea, Schlafly wants to find the dead stars’ prodigal siblings. Those massive stars would have had many low-mass companions that should still be alive and have since wandered from their nursery. The astronomers hope to use upcoming data from the European Space Agency’s Gaia satellite to find those companions and trace their movements back millions of years, says Schlafly. “If they all form a nice, beautiful clump at the centre of the ring, that would be a really spectacular confirmation that this picture is correct.”

Skywatcher Esprit 80 / 400 APO
Canon 6D
Skywatcher EQ6R Pro

PixInsight Core 1.8 Ripley
Adobe Photoshop

18. November 2020 , 21. November 2020 , 11. February 2021 , 12. February 2021

40x10" ISO1600
10x2" ISO1600
98x300" ISO1600
10x5" ISO1600
20x60" ISO1600

Total integration: 8.6 Hours

Flats: ~50
Bias: ~150