Planetary science: A new technique results in planet haul

The discovery of six new exoplanets orbiting three different stars is reported in three papers published in Nature Astronomy this week. The planets, identified using a new technique, range in mass from roughly 2.6 times the mass of the Earth to nearly half the mass of Jupiter, and all orbit very close to their stars.

Over the past decade, it has become clear that in other planetary systems, planets can be situated much nearer to their stars than they are in our Solar System. Carole Haswell and colleagues developed a technique to identify star systems where such close-in planets may be located. When a planet orbits close to a star its atmosphere can be eroded - known as ablation - causing a cloud of gas to dissipate. The authors identified star systems where this ablation process is happening and then examined these systems using a traditional planet-finding technique.

The authors found planets around the first three stars they studied using the new method. Star system DMPP-1 hosts multiple planets with three inner - probably rocky - planets, of 3 to 10 times the mass of the Earth, and a further Neptune-mass planet. The exoplanet around DMPP-2 has half the mass of Jupiter, but orbits its pulsating star in about 5 days. DMPP-3 is a binary star system, with a 2.6 Earth-mass planet orbiting the largest star. These newly discovered exoplanets orbit their stars substantially closer than Mercury does to the Sun.

The versatility of this technique - its ability to detect low mass planets with relatively little data because the nature of the planetary system is already inferred - makes it an effective way to search for new planets, the authors argue.

doi: 10.1038/s41550-019-0973-y

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