Geoscience Reference
In-Depth Information
HABITABLE ZONES FOR EARTH-LIKE PLANETS
IN THE 47 UMa PLANETARY SYSTEM
JIANGHUI JI
∗,†,§
and LIN LIU
‡,§
†
Purple Mountain Observatory, Chinese Academy of Sciences
Nanjing 210008, China
‡
Department of Astronomy, Nanjing University, Nanjing 210093, China
§
National Astronomical Observatory
Chinese Academy of Sciences, Beijing 100012, China
∗
jijh@pmo.ac.cn
The Habitable zones are usually believed to be appropriate environment for
terrestrial planets that can provide the liquid-water, subtle temperature, atmo-
sphere components of CO
2
,H
2
O, and N
2
[Kasting
et al.
,
Icarus
101
(1993)
108], supporting the development and biological evolution of life on their sur-
faces. In this work [see an accompanied paper, Ji
et al.
,
Astrophysical Journal
631
(2005) 1191 for details], we investigated the dynamical architecture of
47 UMa with the planetary configuration of the best-fit orbital solutions by
Fischer
et al.
[
Astrophysical Journal
586
(2003) 1394], to study the existence
of the Earth-like planets in the region for 0
.
05 AU
≤ a ≤
2
.
0 AU for 47 UMa
by numerical simulations. In the study, we found that the “hot Earths” at
0.05 AU
≤ a<
0.4 AU can dynamically survive at least for 1 Myr. The Earth-
like planets can eventually remain in the system for 10 Myr at the areas involved
in mean motion resonance (MMR) (e.g., 3:2 MMR and 9:5 MMR) with the
inner companion. Moreover, we showed that the 2:1 and 3:1 resonances could
be marginally stable, but the 5:2 MMR is unstable. In a dynamical sense, we
point out that the most possible candidate habitable environment is that the
Earth-like planets may bear the orbits of 0
.
8AU
≤ a<
1
.
0AU and 1.0AU
<
a<
1
.
30 AU (except 5:2 MMR) for relatively lower eccentricities. We also con-
ducted similar studies in other multi-planet systems and found the potential
existence of the Earth-like planets in habitable zones.
1. Introduction
The discovery of the first Jupiter-mass planet to the solar-type star 51 Peg
1
dates back 10 years ago. Such historical scientific finding not only uncovers
the prelude to search for other planets or alien worlds outside our own solar
system, but confirms that planets can be formed anywhere about their par-
ent stars in the circumstellar disks (e.g., HD 141569 and Beta Pictoris).
∗
Corresponding author.
377
