First Exomoon Possibly Glimpsed

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Exoplanets are almost old hat to astronomers, who by now have found more than 1,000 such worlds beyond the solar system. The next frontier is exomoons—moons orbiting alien planets—which are much smaller, fainter and harder to find. Now astronomers say they may have found an oddball system of a planet and a moon floating free in the galaxy rather than orbiting a star.

The system showed up in a study using micro lensing, which looks for the bending of starlight due to the gravitational pull of an unseen object between a star and Earth. In this case the massive object might well be a planet and a moon. But the signal is not very clear, the researchers acknowledge, and could instead represent a dim star and a lightweight planet. “An alternate star-plus-planet model fits the data almost as well” as the planet-plus-moon explanation, the scientists reported in a paper that was posted this week on the preprint site arXiv. The study has not yet been peer-reviewed.

"I was excited by this paper," says astronomer Jean Schneider of the Paris Observatory, who was not involved in the research. Exomoons have "become fashionable these days," he adds, and are one of his personal "holy grails." Schneider wrote a paper in 1999 on how to detect exomoons using an alternative method, called transiting. (The transit technique looks for the dimming of a star's light caused when a planet or moon passes in front of the star from Earth's perspective).

Written By: Clara Moskowitz
continue to source article at scientificamerican.com

2 COMMENTS

  1. In this case the massive object might well be a planet and a moon. But the signal is not very clear, the researchers acknowledge, and could instead represent a dim star and a lightweight planet. “An alternate star-plus-planet model fits the data almost as well” as the planet-plus-moon explanation,

    There is really not a lot of difference, in the mass between the body a dim star and that of a large planet, other than radiation levels are high enough for the star to ignite fusion reactions. There are some semantic issues relating to orbits, but the orbit of large planet and the smaller star in a binary system, orbit are similar.
    Similarly, the Earth/Moon system could be considered to be a binary planet system rather than a planet and its satellite.

  2. This sounds like hockey card trading. Got him, need him, got him… ooh, exoplanet with exomoon… need him. This kind of falls under the who cares column. next week they’ll be looking for an exoplanet with a slight limp and the orbital consistency of a border collie on steroids at a sheep fair.

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