Carbon monoxide in the distantly active Centaur (60558) 174P/Echeclus at 6 AU

(60558) 174P/Echeclus is an unusual object that belongs to a class of minor planets called Centaurs, which may be intermediate between Kuiper Belt Objects and Jupiter Family comets. It is sporadically active throughout its orbit at distances too far for water ice to sublimate, the source of activity for most comets. Thus, its coma must be triggered by another mechanism. In 2005, Echeclus had a strong outburst with peculiar behavior that raised questions about the nucleus homogeneity. In order to test nucleus models, we performed the most sensitive search to date for the highly volatile CO molecule via its J=2-1 emission toward Echeclus during 2016 May-June (at 6.1 astronomical units from the Sun) using the Arizona Radio Observatory 10-m Submillimeter Telescope. We obtained a 3.6-sigma detection with a slightly blue-shifted (delta v = -0.55 +- 0.1 km/s) and narrow (FWHM = 0.53 +- 0.23 km/s) line. The data are consistent with emission from a cold gas from the sunward side of the nucleus, as seen in two other comets at 6 AU. We derive a production rate of Q(CO) = (7.7 +- 3.3)x10^26 mol/s, which is capable of driving the estimated dust production rates. Echeclus CO outgassing rate is ~40 times lower than what is typically seen for another Centaur at this distance, 29P/Schwassmann-Wachmann 1. We also used the IRAM 30-m telescope to search for the CO J=2-1 line, and derive an upper limit that is above the SMT detection. Compared to the relatively unprocessed comet C/1995 O1 (Hale-Bopp), Echeclus produces significantly less CO, as do Chiron and four other Centaurs.Comment: 27 pages, 3 figures, 1 table. Accepted for publication in The Astronomical Journa

Millimeter-wavelength characterization of the CO emission of comets 174P/Echeclus, 29P/Schwassmann-Wachmann, and C/2016 R2 (PanSTARRS)

Comets are fascinating minor solar system bodies. They contain some of the most pristine and unprocessed material found in the solar system. As a comet approaches the Sun it displays the characteristic cometary coma and tail. This is due to the release of volatile species through a variety of processes. In the present work I studied the carbon monoxide emission of three very unique comets; 174P/Echeclus, 29P/Schwassmann-Wachmann and C/2016 R2 (PanSTARRS) with different radio telescopes at millimeter wavelengths. After molecular hydrogen, carbon monoxide is the second most abundant molecule in the universe, and is also the most volatile of the species found in most comets. The study of its release mechanisms, content and distribution rwithin the coma of a comet can constrain current models of cometary and solar system formation. Some of the most relevant results of this work include: Detection of carbon monoxide in comet/Centaur 174P/Echeclus -only the third Centaur in which CO has been detected-, evidence for non-correlation between the CO emission and dust production in comet 29P/Schwassmann-Wachmann, and the first detection of 13CO in a comet

Establishing Earth's Minimoon Population through Characterization of Asteroid 2020 CD3

We report on our detailed characterization of Earth's second known temporary natural satellite, or minimoon, asteroid 2020 CD3. An artificial origin can be ruled out based on its area-to-mass ratio and broadband photometry, which suggest that it is a silicate asteroid belonging to the S or V complex in asteroid taxonomy. The discovery of 2020 CD3 allows for the first time a comparison between known minimoons and theoretical models of their expected physical and dynamical properties. The estimated diameter of 1.2(-0.2)(+0.4) m and geocentric capture approximately a decade after the first known minimoon, 2006.RH120, are in agreement with theoretical predictions. The capture duration of 2020 CD3 of at least 2.7 yr is unexpectedly long compared to the simulation average, but it is in agreement with simulated minimoons that have close lunar encounters, providing additional support for the orbital models. 2020 CD3's atypical rotation period, significantly longer than theoretical predictions, suggests that our understanding of meter-scale asteroids needs revision. More discoveries and a detailed characterization of the population can be expected with the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time.Peer reviewe

Recurrent Cometary Activity in Near-Earth Object (3552) Don Quixote

International audienceWe report on observations of activity in near-Earth object (3552) Don Quixote using the Spitzer Space Telescope and ground-based telescopes around its 2018 perihelion passage. Spitzer observations obtained six months before perihelion show extended emission around the target's nucleus that is most likely caused by molecular band emission from either CO2 or CO, but we find no significant emission from dust. Ground-based optical observations taken close to perihelion reveal for the first time activity in the optical wavelengths, which we attribute to solar light reflected from dust particles. IRAM millimeter radio observations taken around the same time are unable to rule out CO as the driver of the molecular band emission observed with Spitzer. The comparison of the gas activity presented here with observations performed during Don Quixote's previous apparition suggests that activity in Don Quixote is recurrent. We conclude that (3552) Don Quixote is most likely a weakly active comet

The Peculiar Volatile Composition of CO-dominated Comet C/2016 R2 (PanSTARRS)

International audienc

The LCO Outbursting Objects Key Project: Overview and Year 1 Status

The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to (1) systematically monitor a sample of previously discovered over the whole sky, to assess the evolutionary state of these distant remnants from the early solar system, and (2) use alerts from existing sky surveys to rapidly respond to and characterize detected outburst activity in all small bodies. The data gathered on outbursts helps to characterize each outburst’s evolution with time, helps to assess the frequency and magnitude distribution of outbursts in general, and contributes to the understanding of outburst processes and volatile distribution in the solar system. The LOOK Project exploits the synergy between current and future wide-field surveys such as ZTF, Pan-STARRS, and LSST, as well as rapid-response telescope networks such as LCO, and serves as an excellent test bed for what will be needed for the much larger number of objects coming from Rubin Observatory. We will describe the LOOK Project goals, the planning and target selection (including the use of NEOexchange as a Target and Observation Manager or “TOM”), and results from the first phase of observations, including the detection of activity and outbursts on the giant comet C/2014 UN271 (Bernardinelli–Bernstein) and the discovery and follow-up of 28 outbursts on 14 comets. Within these outburst discoveries, we present a high-cadence light curve of 7P/Pons–Winnecke with 10 outbursts observed over 90 days, a large outburst on 57P/duToit–Neujmin–Delporte, and evidence that comet P/2020 X1 (ATLAS) was in outburst when discovered