Method to reconstruct exoplanetary spectrum.

We present a method for spectroscopic observations of exoplanets. Coronagraphic image of a star-planet system and its objective spectra are observed simultaneously. Stellar image and objective spectrum without coronagraphic suppression are also obtained as reference. By convolution of the coronagraphic image with the reference stellar spectrum, pseudo-objective spectra are synthesized. The difference between the observed and the synthesized pseudospectra reveals the distinctive features of planetary spectrum. We carry out laboratory demonstration of the proposed technique and show that the planetary spectrum is reconstructed.

Polarization degree analysis of objective spectrum in polarization differential stellar coronagraph.

It is shown that the degree of polarization analysis is useful to find objective spectra of exoplanets immersed in noisy stellar spectra. We report the laboratory experiment of polarization differential objective spectroscopy with a four-quadrant polarization mask coronagraph, where partially polarized planetary signal is expected to be discerned from unpolarized stellar noise. The detection of the planet signal is impeded by the stellar noise remained after subtracting mutually orthogonally polarized components of light. We distinguish clearly the planetary spectrum by use of the degree of polarization. We also show the refinement of the spectrum of the planet model.