Is Kapteyn B Not to Be? [Exo-planet oops]

universetoday.com ^ | on July 7, 2015 | David Dickinson

[BenLurkin]

In 2014, we reported on an exciting new discovery of two new exoplanets orbiting Kapteyn’s Star. The current number of exoplanet discoveries as of July 2015 sits at 1,932 and counting.

An M-class red dwarf, Kapteyn’s Star is relatively nearby at only 13 light years distant. The planetary discovery consisted of a world five times the mass of the Earth in a 48 day orbit (Kapteyn b), and a world seven times the mass of the Earth in a 122 day orbit (Kapteyn c). The discovery was hailed as an example of an ancient—possibly over 11 billion years old—system with its innermost world cast as a ‘super-Earth’ in the habitable zone…

An interesting paper came up in the Astrophysical Journal Letters recently that suggests the exoplanets discovered orbiting Kapteyn’s Star in 2014 may in fact be spurious detections.

The idea of a planetary system around Kapteyn’s Star, real or not, is an interesting tale of exoplanet science. The original discovery was made using the High Accuracy Radial velocity Planetary research (HARP) instrument at the European Southern Observatory, with supporting observations from the Las Campanas and Keck Observatory. You’d think that would make the discoveries pretty air-tight. The planets discovered orbiting Kapteyn’s Star were discerned using the radial velocity method, looking at the spectra of the star for the characteristic tugging of an unseen companion.

Recent research led by Paul Robertson of Pennsylvania State University suggests that the signal for the discovery of Kapteyn B may in fact be the result of stellar activity. Starspots—think sunspots on our own host star—can mimic the spectral signal of an unseen planet. Analyzing the HARPS data, we know that Kapteyn’s Star rotates once every 143 days. Kapteyn-b’s orbit of 48 days is very close to an integer fraction (143/48= 2.979) making it extremely suspicious.

[Tucker39]

Sounds like the perfesser can’t bring himself to come right out and say that there really isn’t an exoplanet there. It’merely a false positive in the signal.

[Verginius Rufus]

I think Walt Whitman claimed to own this star in his poem, “O Kapteyn, my Kapteyn.”

[Verginius Rufus]

I think Walt Whitman claimed to own this star in his poem, “O Kapteyn, my Kapteyn.”

[Redcitizen]

Commander Pavel Andreievich Chekov: Course heading, Kapteyn?

Captain James T. Kirk: Second star to the right and straight on till morning.

[SunkenCiv]

Thanks BenLurkin.

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