Environmental Conditions of Moons

Much as with planets, the amount of stellar radiation received by a moon will help dictate some of its fundamental characteristics and potential habitability. The additional complication with moons lies in their range of masses, from tiny (e.g. Enceladus) to large (e.g. Ganymede or Titan) and how this relates to the retention of volatiles - which we discuss below. In order to make an initial estimate of the orbital radius at which stellar insolation produces a given surface temperature, the...

Dynamical Stability and Chaos

Chaos is a general term that describes a system whose motion is non-repeating over a given timescale, that is, the motion appears random. Stability describes the boundedness of a system a system is stable if changes in its evolution are confined to a certain range. Therefore, one of the most fundamental features of a chaotic system is stability (for a more complete review of chaos theory, consult (Chirikov, 1979)). For example, the Solar System is a chaotic system, but it is stable in the sense...

Sensitivity and Future Methods for Detection of Extrasolar Planets

We have seen that there are a number of ways of detecting the existence of extrasolar planets, most indirect. All the techniques have their own advantages and disadvantages and the different selection effects of these detection methods are summarised in Fig. 1.10, on which are plotted the mass and orbital radii of known exoplanets, together with characteristics of the Solar System planets. Currently employed detection methods are biased towards close-orbiting heavy planets and thus very few...

Remote Sensing Spectroscopy

Venus Atmosphere Absorption Spectrum

Photometric measurements could yield valuable information about an extrasolar terrestrial planet, and may be the only practical characterization technique for faint planets near the detection limit of a particular mission. However, for brighter planets, by far the most powerful technique available for retrieving the characteristics of planetary surfaces and atmospheres is spectroscopy, which samples radiation reflected, scattered or emitted by the planet at different wavelengths. Ultraviolet,...

Exoplanetary Mass Function

Figure 6.5 shows a mass histogram representing all exoplanets as well as solid lines showing sub-samples of short, intermediate and long period exoplanets. All indicate a rise in the number of exoplanets per unit mass towards lower masses despite the selection bias toward finding heavier exoplanets. This overall distribution is similar to the mass function based on subsamples of the long-period and intermediate-period exoplanets. Also over-plotted on this graph for comparison is a dotted line...

Multiple Lens Systems

The lens equation for a multiple lens system is a straight forward generalization of the single lens equation, eq. 3.4, but with more than one lens mass, we can no longer assume that the source, observer and lens system all lie in a single plane. However, as long as the distances to the lens and source DL and DS are much larger than the extent of the lens system, we can assume that the lens system resides a single distance, and define the Einstein radius of the total lens system mass using eq....

Life on Exomoons

Although entirely in the realm of speculation it is nonetheless interesting to consider what life might have to deal with on exomoons. For example, tidal heating may be episodic on geological timescales if driven by moons wandering in and out of resonance conditions. If a moon has a sufficiently massive silicate metal core then in certain situations radiogenic heating, combined with the insulating properties of the outer ice crust, could maintain a partial sub-surface liquid water environment,...

Surface Signatures

In addition to the rich array of spectral features associated with surface composition, such as the optical and near-infrared signatures of rock, ice or water, the Earth also displays spectral signatures due to the plant life that covers much of its surface. Chlorophyll absorbs strongly in the UV and blue lt 0.5 m and in the red 0.6-0.7yU,m , and has slightly less absorption in the green 0.55 m . This characteristic absorption in the red end of the visible spectrum was seen by the Galileo...

O

Top Data and best-fit model for OGLE-2005-BLG-169. Bottom Difference between this model and a single-lens model with the same single lens parameters to, uo, tE, and p . It displays the classical form of a caustic entrance exit that is often seen in binary microlensing events, where the amplitudes and timescales are several orders of magnitude larger than seen here. MDM data trace the characteristic slope change at the caustic exit At 0.092 very well, while the entrance is tracked by...

Dynamical Evolution and Stability

In general, one can consider orbital stability synonymous with the capability of an object in maintaining its orbital parameters i.e., semimajor axis, eccentricity, and inclination at all times. In other words, an object is stable if small variations in its orbital parameters do not progress exponentially, but instead vary sinusoidally. Instability occurs when the perturbative forces create drastic changes in the time variations of these parameters and result in either the ejection of the...

Stability of Ptype Orbits

Numerical simulations have also been carried out for the stability of P-type orbits in binary-planetary systems Ziglin, 1975 Szebehely amp McKenzie, 1981 Dvorak, 1984, 1986 Dvorak, Froeschle, amp Froeschle, 1989 Kubala, Black amp Szebehely, 1993 Holman amp Wiegert, 1999 Broucke, 2001 Pilat-Lohinger, Funk amp Dvorak, 2003 Musielak et al., 2005 . Similar to S-type orbits, in order for a P-type planet to be stable, it has to be at a safe distance from the two stars so that it would be immune from...

Microlensing Planet Detections

Table 3.1 summarizes the properties of the planets discovered by microlensing to date, including four published microlensing exoplanet discoveries Bond et al., 2004 Udalski et al., 2005 Beaulieu et al., 2006 Gould et al., 2006 plus a 2-planet system that will soon be published Gaudi et al. 2007, Bennett et al. 2007, both in preparation . The microlensing discoveries are compared to other known exoplanets in Fig. 3.9. The first planet discovered by microlensing is shown in Fig. 3.10. The light...

Timing of Pulsating White Dwarfs

During their cooling, white dwarfs may pass through periods of pulsational instability, where the whole star oscillates coherently with a period of minutes. While not as stable or rapid as pulsars, these white dwarfs allow very precise long term observations, including precise measurements of any deviation from stable, steadily slowing oscillations. That is, in the same way as for pulsars, the timing of the white dwarf pulsations allows for high precision detection of any planets orbiting the...

Description of the Doppler Method

Currently, there are two major Doppler methods one using high resolution cross-dispersed echelle spectrographs the echelle method and the other using dispersed fixed-delay interferometers the DFDI method . Both methods have been successfully used for detecting new planets e.g., Butler et al. 2006 for a summary of exoplanets detected by the Doppler techniques . Here we briefly describe both methods. 2.2.1 The High Resolution Cross-Dispersed Echelle Method The RV method using high resolution...