Mystery Of Distant, Obscure Planetary System – Solved After Eight Years

Eddie Gonzales Jr. – MessageToEagle.com – Astronomers using the combined power of two Hawaii telescopes have taken groundbreaking, sharp new images of a distant planetary system that likely resembles a baby version of our solar system.

Using Subaru Telescope and W. M. Keck Observatory, astronomers obtained and analyzed data for an infant Sun-like star named LkCa 15.

LKCA 15. An expanded view of the central part of the cleared region around LkCa 15, showing a composite of two reconstructed images (blue: 2.1 microns, from November 2010; red: 3.7 microns) for LkCa 15. The location of the central star is also marked. Credit: Kraus&Ireland, 2011

This data appear to solve this mystery; most of the light thought to come from the three candidate planets appears to originate from a disk of gas and dust.

“LkCa 15 is a highly complex system,” said Thayne Currie, lead author of the study and astrophysicist at NASA-Ames Research Center and the Subaru Telescope. “Prior to analyzing our Keck & Subaru data and given the same prior aperture masking data, we also would have concluded that LkCa 15 has three detected superjovian planets.”

LkCa 15 is surrounded by a massive protoplanetary disk made of gas and dust, which are the building blocks of planets. Early analysis of this disk showed it has a large cavity depleted of dust – a tell-tale sign that much of the disk material has already been incorporated into massive, developing planetary embryos, or “protoplanets.”

Artist’s concept of planets forming around LkCa 15. (NASA/JPL-Caltech)

While the study rules out very bright superjovian planets, Currie says it is likely that fainter, less massive planets may be in the LkCa 15 system: perhaps those like Jupiter and Saturn.

“The planets in this infant solar system could actually be a lot more like our own solar system than previously thought. They are certainly there somewhere, possibly embedded in the disk. We will keep trying to find them,” said Currie.

The findings were made using high-resolution images of the LkCa 15 system obtained from complementary instruments on Maunakea. At Subaru, researchers used a new cutting-edge planet imaging instrument – the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled to the CHARIS integral field spectrograph to obtain extremely sharp images at near-infrared wavelengths. The team also used Keck Observatory’s powerful adaptive optics system and Near-Infrared Camera (NIRC2) to obtain new sharp images at longer, thermal-infrared wavelengths where young planets emit more light.

The combined data showed that most of the light surrounding LkCa 15 originates from an extended arc-like structure – the visible edge of another component of LkCa 15’s disk. This arc has the same brightness previously attributed to planets around LkCa 15.

The nearly decade-old KOA data for LkCa 15 play a unique role in understanding this planetary system. When compared with new Keck Observatory and Subaru Telescope data, the KOA data also showed that light emitted from LkCa 15’s arc-like structure is static over the course of eight years.

“This is consistent with a fixed, disk-like structure. Without the KOA, we would not have been able to know this key fact,” said Currie.

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Written by Eddie Gonzales Jr. – MessageToEagle.com Staff Writer