ALMA Observes Exoplanet Formation Around V1247 Orionis

The quest to discover how planets found in the far reaches of the universe are born has taken a new, crucial twist.

A new study by an international team of scientists, led by Stefan Kraus from the University of Exeter, has given a fascinating new insight into one of the most respected theories of how planets are formed.

Young stars start out with a massive disk of gas and dust that over time, astronomers think, either diffuses away or coalesces into planets and asteroids.

However, scientists are still searching for a complete understanding of how these early formations come together to form asteroid-sized objects. One reason has been that drag in the disk produced by surrounding gas makes the grains move inward toward the star - which can in turn deplete the disk rapidly in a process known as "radial drift."

In the new research, the team use high powered telescopes to target the star V1247 Orionis -, a young, hot star surrounded by a dynamic ring of gas and dust.

The team produced a detailed image of the star and its surrounding dust disc, shown in two parts: a clearly defined central ring of matter and a more delicate crescent structure located further out.

The region between the ring and crescent, visible as a dark strip, is thought to be caused by a young planet carving its way through the disc. As the planet moves around in its orbit, its motion creates areas of high pressure on either side of its path, similar to how a ship creates bow waves as it cuts through water.

These areas of high pressure could become protective barriers around sites of planet formation; dust particles are trapped within them for millions of years, allowing them the time and space to clump together and grow.

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Extreme Asymmetry in the Disk of V1247 Ori

Extreme Asymmetry in the Disk of V1247 Ori

Authors:

Ohta et al

Abstract:

We present the first near-infrared scattered-light detection of the transitional disk around V1247 Ori, which was obtained using high-resolution polarimetric differential imaging observations with Subaru/HiCIAO. Our imaging in the H band reveals the disk morphology at separations of ~0.14"-0.86" (54-330 au) from the central star. The polarized intensity (PI) image shows a remarkable arc-like structure toward the southeast of the star, whereas the fainter northwest region does not exhibit any notable features. The shape of the arm is consistent with an arc of 0.28" ± 0.09" in radius (108 au from the star), although the possibility of a spiral arm with a small pitch angle cannot be excluded. V1247 Ori features an exceptionally large azimuthal contrast in scattered, polarized light; the radial peak of the southeastern arc is about three times brighter than the northwestern disk measured at the same distance from the star. Combined with the previous indication of an inhomogeneous density distribution in the gap at ≲46 au, the notable asymmetry in the outer disk suggests the presence of unseen companions and/or planet-forming processes ongoing in the arc.