Report - School of Physics

where the distance D is in pc, R J the radius expressed in Jupiter units, and T the
temperature in K. Together with the expected sensitivity performances of ALMA,
this indicates that a Jupiter would be detectable only out to about 1 pc. In the case
of a ‘hot Jupiter’ (R = 1.5 R J , T = 1000 K), this limit is pushed to a few parsecs,
but still not far enough to actually encompass any useful star. On the other hand,
a proto-Jupiter (with R = 30 R J and T = 2500 K) would be detectable in a matter
of minutes to hours out to several tens of parsecs.
The contrast between the star and the surrounding bodies, a critical factor at shorter
wavelengths (visible–infrared), becomes an advantage in the case of ALMA. The
contrast factor is of the order of 1000, which is well within the dynamic range of the
detectors, and the bright central source helps maintaining the optimal coherence of
the interferometer. So, while ALMA is not expected to contribute significantly to
the study of mature planets, its contribution will be very significant for studying
early stages of planet formation, from nebula to protoplanet.
2.1.7 Other Searches
The upper right-hand section of Figure 1 indicates some miscellaneous search methods.
Jupiter’s magnetosphere is known to produce strong emission of radio waves.
These decametric bursts are targeted by a number of collaborative efforts in the
radio community, as summarised in Table 4. As noted in Section 2.2.2, Gaia might
also detect a few protoplanetary collisions photometrically (Zhang & Sigurdsson,
2003), although whether they could ever be recognised as such, buried within such
a vast volume of other variables, has not been assessed.
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