Quan-Zhi Ye

AN EARLY LOOK OF COMET C/2013 A1 (SIDING SPRING): BREATHTAKER OR NIGHTMARE?

The dynamically new comet, C/2013?A1 (Siding Spring), is to make a close approach to Mars on 2014 October 19 at 18:30 UT at a distance of 40 ? 1 Martian radii. Such an extremely rare event offers a precious opportunity for the spacecrafts on Mars to closely study a dynamically new comet itself as well as the planet-comet interaction. Meanwhile, the high-speed meteoroids released from C/Siding Spring also pose a threat to physically damage the spacecrafts. Here we present our observations and modeling results of C/Siding Spring to characterize the comet and assess the risk posed to the spacecrafts on Mars. We find that the optical tail of C/Siding Spring is dominated by larger particles at the time of the observation. Synchrone simulation suggests that the comet was already active in late 2012 when it was more than 7 AU from the Sun. By parameterizing the dust activity with a semi-analytic model, we find that the ejection speed of C/Siding Spring is comparable to comets such as the target of the Rosetta mission, 67P/Churyumov-Gerasimenko. Under a nominal situation, the simulated dust cone will miss the planet by about 20 Martian radii. At the extreme ends of uncertainties, the simulated dust cone will engulf Mars, but the meteoric influx at Mars is still comparable to the nominal sporadic influx, seemly indicating that an intense and enduring meteoroid bombardment due to C/Siding Spring is unlikely. Further simulation also suggests that gravitational disruption of the dust tail may be significant enough to be observable at Earth.

1I/2017 U1 (‘Oumuamua) is Hot: Imaging, Spectroscopy, and Search of Meteor Activity

1I/2017 U1 (`Oumuamua), a recently discovered asteroid in a hyperbolic orbit, is likely the first macroscopic object of extrasolar origin identified in the solar system. Here, we present imaging and spectroscopic observations of \textquoteleft Oumuamua using the Palomar Hale Telescope as well as a search of meteor activity potentially linked to this object using the Canadian Meteor Orbit Radar. We find that \textquoteleft Oumuamua exhibits a moderate spectral gradient of

Will comet 209P/LINEAR generate the next meteor storm?

10\%\pm6\%~(100~\mathrm{nm})^{-1}

Radar Observations of the 2011 October Draconid Outburst

, a value significantly lower than that of outer solar system bodies, indicative of a formation and/or previous residence in a warmer environment. Imaging observation and spectral line analysis show no evidence that \textquoteleft Oumuamua is presently active. Negative meteor observation is as expected, since ejection driven by sublimation of commonly-known cometary species such as CO requires an extreme ejection speed of

The unexpected 2012 Draconid meteor storm

\sim40

Dormant Comets Among the Near-Earth Object Population: A Meteor-Based Survey

m s

BANGS AND METEORS FROM THE QUIET COMET 15P/FINLAY

^{-1}

THE PROGRESSIVE FRAGMENTATION OF 332P/IKEYA–MURAKAMI

at

GONE IN A BLAZE OF GLORY: THE DEMISE OF COMET C/2015 D1 (SOHO)

\sim100

Tibet's Ali: Asia's Atacama?

au in order to reach the Earth. No obvious candidate stars are proposed as the point of origin for \textquoteleft Oumuamua. Given a mean free path of