A team of astronomers from Northern Arizona University and Lowell Observatory has discovered cometary activity on 2014 OG392, a distant centaur object discovered in 2014.
This image, taken by the Large Monolithic Imager on the 4.3-m Lowell Discovery Telescope on October 14, 2020, shows C/2014 OG392 (PANSTARRS) and its extensive coma; the dashed lines are star trails caused by the long exposure. Image credit: Northern Arizona University.
Centaurs are minor planets thought to have originated in the outer region of our Solar System known as the Kuiper Belt.
Active centaurs enigmatically display prominent comet-like features such as comae or tails even though they orbit in the gas giant region where it is too cold for water to readily sublimate.
Only 18 active centaurs have been identified since 1927 and, consequently, the underlying activity mechanisms are still poorly understood.
“We report the discovery of activity emanating from 2014 OG392, based on archival images we uncovered,” said lead author Colin Chandler, a doctoral student at Northern Arizona University.
2014 OG392 orbits between 10 and 15 AU (astronomical units) where its equilibrium temperature would be around minus 213 degrees Celsius (minus 351 degrees Fahrenheit).
Chandler and colleagues initially found suspected cometary activity in the archival images of the object from the Dark Energy Camera at the Cerro Tololo Inter-American Observatory.
They then carried out a follow-up observing campaign with the DECam, the Las Campanas Observatory 6.5-m Walter Baade Telescope, and the 4.3-m Lowell Discovery Telescope.
“We detected a coma as far as 400,000 km (248,548 miles) from 2014 OG392 and our analysis of sublimation processes and dynamical lifetime suggest carbon dioxide and/or ammonia are the most likely candidates for causing activity on this and other active centaurs,” the astronomers said.
“We developed a novel technique that combines observational measurements, for example, color and dust mass, with modeling efforts to estimate such characteristics as the object’s volatile sublimation and orbital dynamics.”
As a result of the team’s discovery, 2014 OG392 has recently been reclassified as a comet, and will be known as C/2014 OG392 (PANSTARRS).
“I’m very excited that the Minor Planet Center awarded a new comet designation befitting the activity we discovered on this unusual object,” Chandler said.
The researchers presented their results at the 52nd Division for Planetary Sciences (DPS) of the American Astronomical Society 2020 meeting and in a paper in the Astrophysical Journal Letters.
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Colin Orion Chandler et al. 2020. Cometary Activity Discovered on a Distant Centaur: A Nonaqueous Sublimation Mechanism. ApJL 892, L38; doi: 10.3847/2041-8213/ab7dc6
C.O. Chandler et al. 2020. Cometary Activity Discovered on Centaur 2014 OG39. DPS52, abstract # 404.02
