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Asami Takumi

Publications and source records attributed to Asami Takumi.

2 recordsLinked to original sources

Multicolor Photometry of Tiny Near-Earth Asteroid 2015 RN$_{35}$ Across a Wide Range of Phase Angles: Possible Mission Accessible A-type Asteroid

Studying small near-Earth asteroids is important to understand their dynamical histories and origins as well as to mitigate the damage of the asteroid impact to the Earth. We report the results of multicolor photometry of the tiny near-Earth asteroid 2015 RN$_{35}$ using the 3.8 m Seimei telescope in Japan and the TRAPPIST-South telescope in Chile over 17 nights in 2022 December and 2023 January. We observed 2015 RN$_{35}$ across a wide range of phase angles from 2$^{\circ}$ to 30$^{\circ}$ in the $g$, $r$, $i$, and $z$ bands in the Pan-STARRS system. These lightcurves show that 2015 RN$_{35}$ is in a non-principal axis spin state with two characteristic periods of $1149.7\pm0.3$ s and $896.01\pm0.01$ s. We found that a slope of a visible spectrum of 2015 RN$_{35}$ is as red as asteroid (269) Justitia, one of the very red objects in the main belt, which indicates that 2015 RN$_{35}$ can be classified as an A- or Z-type asteroid. In conjunction with the shallow slope of the phase curve, we suppose that 2015 RN$_{35}$ is a high-albedo A-type asteroid. We demonstrated that surface properties of tiny asteroids could be well constrained by intensive observations across a wide range of phase angles. 2015 RN$_{35}$ is a possible mission accessible A-type near-Earth asteroid with a small $Δv$ of 11.801 km s$^{-1}$ in the launch window between 2030 and 2035.

astro-ph.EP

Photometry and Polarimetry of 2010 XC$_{15}$: Observational Confirmation of E-type Near-Earth Asteroid Pair

Asteroid systems such as binaries and pairs are indicative of physical properties and dynamical histories of the Small Solar System Bodies. Although numerous observational and theoretical studies have been carried out, the formation mechanism of asteroid pairs is still unclear, especially for near-Earth asteroid (NEA) pairs. We conducted a series of optical photometric and polarimetric observations of a small NEA 2010 XC$_{15}$ in 2022 December to investigate its surface properties. The rotation period of 2010 XC$_{15}$ is possibly a few to several dozen hours and color indices of 2010 XC$_{15}$ are derived as $g-r=0.435\pm0.008$, $r-i=0.158\pm0.017$, and $r-z=0.186\pm0.009$ in the Pan-STARRS system. The linear polarization degrees of 2010 XC$_{15}$ are a few percent at the phase angle range of 58$^{\circ}$ to 114$^{\circ}$. We found that 2010 XC$_{15}$ is a rare E-type NEA on the basis of its photometric and polarimetric properties. Taking the similarity of not only physical properties but also dynamical integrals and the rarity of E-type NEAs into account, we suppose that 2010 XC$_{15}$ and 1998 WT$_{24}$ are of common origin (i.e., asteroid pair). These two NEAs are the sixth NEA pair and first E-type NEA pair ever confirmed, possibly formed by rotational fission. We conjecture that the parent body of 2010 XC$_{15}$ and 1998 WT$_{24}$ was transported from the main-belt through the $ν_6$ resonance or Hungaria region.

astro-ph.EP