This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The Orion Nebula is a large star-forming region visible to the naked eye. Some of the young stars in the nebula are surrounded by disks of gas and dust in which planets form.
Radiation from the massive central star, 1 Ori C1 (Theta-1 Orionis C1), gradually strips material from these disks, giving them shapes that resemble tadpoles. The disks are losing mass so rapidly that, given the age of the stars (around 1 million years), they should have disappeared long ago. The large gas shell surrounding the central star poses another puzzle.
The star sets the surrounding gas in motion, causing the shell to expand at around 13 kilometers per second (8 miles per second). Extrapolating backward from this speed suggests that the shell formed only a few hundred thousand years ago. The stars are therefore much older than both the gas shell and the dust disks (the "tadpoles") appear to be.
This is the age paradox of the Orion Nebula. Leiden astronomer Maite Wilhelm and her colleagues propose a new scenario that could explain both puzzles. They suggest that 1 Ori C1, which has a mass around 33.5 times that of the sun, formed when a binary star system merged.
A binary system consists of two stars that orbit a common center of mass under the influence of their mutual gravity. The researchers suspect that a third star disrupted the system, knocking one of the stars out of its stable orbit and eventually causing the two stars to collide. If the two stars did merge a few hundred thousand years ago, the resulting star's luminosity (the amount of light it emits) must have increased sharply from that point onward.
The researchers used computer simulations to investigate whether this scenario could explain the observations. The study is published in the journal Astronomy & Astrophysics. The simulations showed that the scenario is plausible.
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