ﻻ يوجد ملخص باللغة العربية
Dynamically new comet C/2011 L4 (PanSTARRS) is one of the brightest comets since the great comet C/1995 O1 (Hale-Bopp). Here, we present our multi-wavelength observations of C/2011 L4 during its in-bound passage to the inner Solar system. A strong absorption band of water ice at 2.0 $mu$m was detected in the near infrared spectra, taken with the 8-m Gemini-North and 3-m IRTF telescopes. The companion 1.5 $mu$m band of water ice, however, was not observed. Spectral modeling show that the absence of the 1.5 $mu$m feature can be explained by the presence of sub-micron-sized fine ice grains. No gas lines (i.e. CN, HCN or CO) were observed pre-perihelion either in the optical or in the sub-millimeter. 3-$sigma$ upper limits to the CN and CO production rates were derived. The comet exhibited a very strong continuum in the optical and its slope seemed to become redder as the comet approached the Sun. Our observations suggest that C/2011 L4 is an unusually dust-rich comet with a dust-to-gas mass ratio $>$ 4.
We present pre-perihelion infrared 8 to 31 micron spectrophotometric and imaging observations of comet C/2012 K1 (Pan-STARRS), a dynamically new Oort Cloud comet, conducted with NASAs Stratospheric Observatory for Infrared Astronomy (SOFIA) facility
A sequence of events, dominated by two outbursts and ending with the preperihelion disintegration of comet C/2017 S3, is examined. The onset times of the outbursts are determined with high accuracy from the light curve of the nuclear condensation bef
P/2011 S1 (Gibbs) is an outer solar system comet or active Centaur with a similar orbit to that of the famous 29P/Schwassmann-Wachmann 1. P/2011 S1 (Gibbs) has been observed by the Pan-STARRS 1 (PS1) sky survey from 2010 to 2012. The resulting data a
High-quality white-light images from the SECCHI/HI-1 telescope onboard STEREO-B reveal high-velocity evanescent clumps [HVECs] expelled from the coma of the C/2011 L4 [Pan-STARRS] comet. Animated images provide evidence of highly dynamic ejecta movin
We present our results on the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer (ACIS) observations of the bright Oort Cloud comets C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS). ISON was observed between 2013 October 31-November 06 during var