A protoplanetary disk seen around a distant star, shaped like a typical flying saucer, is puzzling astronomers who recently recorded the temperature of the object. Particles within the structure are significantly cooler than current planetary models predict.
The stellar body, known as 2MASS J16281370-2431391, sits inside the Rho Ophiuchi star-forming region. The star and its accompanying disk are located roughly 400 light-years away from our own planetary system. Images taken of the structure, sitting edge-on as seen from Earth, resemble a typical representation of an alien flying saucer.
An international team of astronomers, including researchers from the Laboratoire d'Astrophysique de Bordeaux in France, recorded the temperature of the protoplanetary disk, finding it to be significantly cooler than expected - just 7 degrees Celsius above absolute zero. Protoplanetary disks are an early stage of planet formation. Most models of planetary formation suggest these particles - roughly 1.25 inch in length - should have a temperature of roughly 15 to 20 degrees above absolute zero.
Examination of carbon monoxide in the structure, using the Atacama Large Millimeter/submillimeter Array (ALMA), recorded something unusual - a negative signal in certain parts of the disk. Such a result would normally be impossible. The findings were compared to observations made at the IRAM telescope in Spain. Astronomers realized the odd readings were the result of viewing the disk in front of the brighter nebula sitting behind the disk.
"This diffuse glow is too extended to be detected by ALMA, but the disc absorbs it. The resulting negative signal means that parts of the disc are colder than the background. The Earth is quite literally in the shadow of the Flying Saucer!" Stephane Guilloteau of the Laboratoire d'Astrophysique de Bordeaux said.
Astronomers are still unsure what to make of the findings. It is possible that larger particles of matter in these structures are cooler than smaller clumps of matter. How warm these pieces of matter are can affect the method by which they form new planets, asteroids, and comets.
Analysis of the flying saucer structure and the unusually low temperature recorded for small particles in the structure was detailed in the journal Astronomy and Astrophysics.