Geoscience Reference
In-Depth Information
U
C7-b
N
10
K10-b
20000
K20-b
55 Cnc-e
5
E
V
K18-b
3
K11-b
55Cnc-e (1)
(2)
2
GJ 1214b
N
1
U
K11-d
10000
K11-f
C-7b
K-10b
0.5
0.3
8000
K11-e
6000
0.7
1
2
3
5
7
10
20
T=2650 at 10 bars
Mass [M
Earth
]
1
10
Fig. 9.8
Density vs mass of transiting super-Earths.
The data for the known transiting super-Earths and
mini-Neptunes is shown, as well as the relationships
for the four rocky representative compositions
described in the text. Earth, Venus, Uranus and
Neptune are shown for reference. (See Color Plate 9).
Mass (M
Earth
)
Fig. 9.7
Mass-Radius relationships for hot low-mass
planets. Data for CoRoT-7b (Bruntt
et al
., 2010; Hatzes
et al
., 2011), Kepler-10b (K-10, Batalha
et al
., 2011) and
55Cnc-e are shown ((1) Demory
et al
., 2011, (2) Winn
et al
., 2011 and (3) Gillon
et al
., 2012). Uranus (U) and
Neptune (N) are shown for reference. Four
representative rocky compositions are shown: no iron,
Earth-like (33% iron core, 67% silicate mantle with 0.1
of iron by mol), super-Mercury (63% iron core, 37%
silicate mantle no iron), and a pure iron planet. Any
planet above the no-iron line necessarily has
considerable amounts of volatiles. The range of rocky
planets lies within the shaded area. Two types of
volatiles compositions are shown: 0.1-0.01% of H-He
(pink), and 10-50% of water (blue) above an Earth-like
nucleus. The relationships correspond to calculations
of planets with effective temperature of 2000 K,
equivalent to a temperature of 2650 K at 10 bars.
CoRoT-7b
. This planet was the first transiting
super-Earth detected (Leger
et al
. 2009). With an
orbital period of less than a day around a sun-
like star, the insolation received by this planet
is one of the highest known. Its effective surface
temperature is estimated to be
2000 K. With im-
proved stellar parameters its discovery radius was
revised to a smaller value of R
∼
0.10 R
E
(Bruntt
et al
., 2010). Its mass, on the other hand,
has been under considerable debate. The star
CoRoT is a somewhat young (1-2.3 Gy) very
active star, which makes the radial velocity data
very noisy. Hatzes
et al
. (2011) proposed a sim-
ple technique to remove the activity of the star
by assuming that it changes on a much shorter
time-scale than the radial velocity signal from
the planet. By removing a baseline from every
night where there were more than two measure-
ments available, they revealed a ''clean'' sinu-
soidal radial velocity curve corresponding to a
mass of 7.26
=
1.58
±
a given planet may allow more volatiles. This
is the trade-off between the building blocks of
different density that gives rise to the degeneracy
in composition. Thus, any suggested values for
the amount of volatiles in a low-mass planet
discussed below are illustrative. Figures 9.6 and
9.7 show the M-R relationships for planets with
different amounts of volatiles above an Earth-like
nucleus relevant to the planets described below.
Figure 9.8 shows the density versus mass.
1
.
36 M
E
consistent with the major-
ity of the other studies. This technique contrasts
with that proposed by Pont
et al
. (2011), who used
±
