domingo, 20 de octubre de 2013


Within the framework of cooperation of the draft study and research of comet C/2012 S1 ISON the astrophysicist, and member of the Investigation Cometary FB Astrophysic Jian-Yang Li | Planetary Science Institute, has published some scientific results of astronomical research comet C / 2012 S1 ISON : 1.- The dust coma is mostly composed of sub-µm-sized particles emitted at speeds of tens of meters per second. 2.- The A(θ)fρ, a quantity to measure the dust production rate, is 1339 and 1239 cm in the F606W and F438W filters, respectively, in apertures <1.6″ in radius. 3.- The dust colors are slightly redder than solar, with a slope of 5.0±0.2% per 100 nm, and increase to >10% per 100 nm 10,000 km down the tail. The color properties of ISON’s coma is similar to that of Comet Hale-Bopp. A sunward jet is about 1.6″ long, at a position angle of 291°, with an opening angle of ~45º. The shape and orientation of the jet does not change over 19 hours of our observations, suggesting a circumpolar jet. The jet indicates that the rotation pole is pointing within 30° of (RA, Dec) = (330°, 0°). There are two interesting implications from our observation: The existence of ice grains in the inner coma is the best explanation we could find for the change of color within the coma. The comet always faces the Sun with one side, and the other side is always in dark, therefore probably still retaining abundant supervolatiles (CO and/or CO2). This situation won’t change until the last week before perihelion. When the original night side is suddenly exposed to strong sunlight at within Mercury’s orbit, large outbursts might be triggered. While we are continuing our analysis, we were able to put an upper limit of the radius of the nucleus as 2 km from our images. The top image is the image of ISON taken by Hubble on October 9. The bottom image is an enhancement to reveal the non-symmetric structures in the coma, such as jet. Credit: NASA/ESA/Z. Levay The real color of comet ISON :

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