摘要：Context. The near-Earth asteroid (3200) Phaethon is an intriguing
object: its perihelion is at only 0.14 au and is associated with the Geminid meteor
stream.
Aims. We aim to use all available disk-integrated optical data to derive
a reliable convex shape model of Phaethon. By interpreting the available space- and
ground-based thermal infrared data and Spitzer spectra using a
thermophysical model, we also aim to further constrain its size, thermal inertia, and
visible geometric albedo.
Methods. We applied the convex inversion method to the new optical data
obtained by six instruments and to previous observations. The convex shape model was then
used as input for the thermophysical modeling. We also studied the long-term stability of
Phaethon’s orbit and spin axis with a numerical orbital and rotation-state integrator.
Results. We present a new convex shape model and rotational state of
Phaethon: a sidereal rotation period of 3.603958(2) h and ecliptic coordinates of the
preferred pole orientation of (319°, −39°) with
a 5° uncertainty. Moreover, we
derive its size (D = 5.1 ±
0.2 km), thermal inertia (Γ
= 600 ± 200
J
m–2
s–1/2
K–1), geometric
visible albedo (pV
= 0.122 ± 0.008), and estimate the macroscopic surface roughness. We
also find that the Sun illumination at the perihelion passage during the past several
thousand years is not connected to a specific area on the surface, which implies
non-preferential heating.
