TY  - JOUR
T1  - (3200) Phaethon: Bulk density from Yarkovsky drift detection
A1  - Hanuš, J.
A1  - Vokrouhlický, D.
A1  - Delbo', M.
A1  - Farnocchia, D.
A1  - Polishook, D.
A1  - Pravec, P.
A1  - Hornoch, K.
A1  - Kučáková, H.
A1  - Kušnirák, P.
A1  - Stephens, R.
A1  - Warner, B.
JA  - Astronomy and Astrophysics
Y1  - 2018
VL  - 620
SP  - L8
SN  - 0004-6361
UR  - https://ui.adsabs.harvard.edu/abs/2018A&A...620L...8H
KW  - asteroids: individual: (3200) Phaethon
KW  - astrometry
KW  - Astrophysics - Earth and Planetary Astrophysics
KW  - celestial mechanics
KW  - methods: numerical
KW  - methods: observational
KW  - minor planets
N2  - Context. The recent close approach of the near-Earth asteroid (3200)
M1  - ={Phaethon offered a rare opportunity to obtain high-quality observational
M1  -  data of various types. <BR /> Aims: We used the newly obtained optical
M1  -  light curves to improve the spin and shape model of Phaethon and to
M1  -  determine its surface physical properties derived by thermophysical
M1  -  modeling. We also used the available astrometric observations of
M1  -  Phaethon
M1  -  including those obtained by the Arecibo radar and the Gaia
M1  -  spacecraft
M1  -  to constrain the secular drift of the orbital semimajor
M1  -  axis. This constraint allowed us to estimate the bulk density by
M1  -  assuming that the drift is dominated by the Yarkovsky effect. <BR />
M1  -  Methods: We used the convex inversion model to derive the spin
M1  -  orientation and 3D shape model of Phaethon
M1  -  and a detailed numerical
M1  -  approach for an accurate analysis of the Yarkovsky effect. <BR />
M1  -  Results: We obtained a unique solution for Phaethon's pole orientation
M1  -  47 ° ) ecliptic longitude and latitude (both with an
M1  -  uncertainty of 5°)
M1  -  and confirm the previously reported thermophysical
M1  -  properties (D = 5.1 ± 0.2 km
M1  -  Γ = 600 ± 200J m<SUP>-2</SUP>
M1  -  s<SUP>-0.5</SUP> K<SUP>-1</SUP>). Phaethon has a top-like shape with
M1  -  possible north-south asymmetry. The characteristic size of the regolith
M1  -  2 cm. The orbit analysis reveals a secular drift of the
M1  -  (6.9 ± 1.9)×10<SUP>-4</SUP> au Myr<SUP>-1</SUP>. With
M1  -  the derived volume-equivalent size of 5.1 km
M1  -  the bulk density is 1.67 ±
M1  -  5.8 km
M1  -  as
M1  -  suggested by radar data
M1  -  the bulk density would decrease to 1.48 ± 0.42
M1  -  g cm<SUP>-3</SUP>. We further investigated the suggestion that Phaethon
M1  -  may be in a cluster with asteroids (155140) 2005 UD and (225416) 1999 YC
M1  -  that was formed by rotational fission of a critically spinning parent
M1  -  body. <BR /> Conclusions: Phaethon's bulk density is consistent with
M1  -  typical values for large (&gt; 100 km) C-complex asteroids and supports
M1  -  its association with asteroid (2) Pallas
M1  -  as first suggested by
M1  -  dynamical modeling. These findings render a cometary origin unlikely for
M1  -  Phaethon.
M1  -  10.1051/0004-6361/201834228
M1  -  eprint: arXiv:1811.10953}
ER  -