Study in Contrasts

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Science  28 Mar 2014:
Vol. 343, Issue 6178, pp. 1405
DOI: 10.1126/science.343.6178.1405-a

In order to image exoplanets directly, it helps to increase the contrast between the extremes of the bright stellar host and any faint companion. Close et al. report the use of an advanced adaptive optics system to observe HD142527, a young star that hosts a disk of gas and dust, whose well-studied morphology includes a large gap that sparked discussion of active planet formation there. The authors confirm the presence of a companion at only 12 times the Earth-Sun distance, detecting it in visible light emitted by gas accreting onto it. This lower-mass stellar companion orbits the primary star just at the inner edge of the gap, implying partial responsibility for clearing its neighborhood, just as planets are thought to do in other cleared disks. At the specific wavelength of light where gas accretion releases energy, the brightness difference between the two bodies is less pronounced than at other wavelengths, where the difference instead depends largely on their extremely distinct temperatures. The detection of this accreting companion in visible light should encourage more searches for planets that are still accumulating gas in their formation phase, when observers can take advantage of the favorable contrast levels.

Astrophys. J. Lett. 781, 10.1088/2041-8205/781/2/L30 (2014).

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