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تسجيل مستخدم جديدOptical and Near-Infrared Polarimetry for a Highly Dormant Comet 209P/LINEAR
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We conducted an optical and near-infrared polarimetric observation of the highly dormant Jupiter-Family Comet, 209P/LINEAR. Because of its low activity, we were able to determine the linear polarization degrees of the coma dust particles and nucleus independently, that is $P_n$=30.3$^{+1.3}_{-0.9}$% at $alpha$=92.2$^circ$ and $P_n$=31.0$^{+1.0}_{-0.7}$% at $alpha$=99.5$^circ$ for the nucleus, and $P_c$=28.8$^{+0.4}_{-0.4}$% at $alpha$=92.2$^circ$ and 29.6$^{+0.3}_{-0.3}$% at $alpha$=99.5$^circ$ for the coma. We detected no significant variation in $P$ at the phase angle coverage of 92.2$^circ$-99.5$^circ$, which may imply that the obtained polarization degrees are nearly at maximum in the phase-polarization curves. By fitting with an empirical function, we obtained the maximum values of linear polarization degrees $P_mathrm{max}$=30.8% for the nucleus and $P_mathrm{max}$=29.6% for the dust coma. The $P_mathrm{max}$ of the dust coma is consistent with those of dust-rich comets. The low geometric albedo of $P_v$=0.05 was derived from the slope-albedo relationship and was associated with high $P_mathrm{max}$. We examined $P_mathrm{max}$-albedo relations between asteroids and 209P, and found that the so-called Umov law seems to be applicable on this cometary surface.
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