51 Pegasi - Maunder minimum candidate?

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51 Pegasi - Maunder minimum candidate?

Post by Sirius_Alpha on 26th November 2009, 3:27 am

51 Pegasi - a planet-bearing Maunder minimum candidate
http://arxiv.org/abs/0911.4862

Abstract wrote:We observed 51 Peg, the first detected planet-bearing star, in a 55 ks XMM-Newton pointing and in 5 ks pointings each with Chandra HRC-I and ACIS-S. The star has a very low count rate in the XMM observation, but is clearly visible in the Chandra images due to the detectors' different sensitivity at low X-ray energies. This allows a temperature estimate for 51 Peg's corona of T<1MK; the detected ACIS-S photons can be plausibly explained by emission lines of a very cool plasma near 200eV. The constantly low X-ray surface flux and the flat-activity profile seen in optical CaII data suggest that 51 Peg is a Maunder minimum star; an activity enhancement due to a Hot Jupiter, as proposed by recent studies, seems to be absent. The star's X-ray fluxes in different instruments are consistent with the exception of the HRC Imager, which might have a larger effective area below 200eV than given in the calibration.

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Re: 51 Pegasi - Maunder minimum candidate?

Post by Stalker on 26th November 2009, 4:00 am

what mean Maunder minimum?
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Re: 51 Pegasi - Maunder minimum candidate?

Post by Sirius_Alpha on 26th November 2009, 5:38 am

The Maunder minimum is a period of abnormally low solar activity way back in the 1800's or so. It resulted in a sort of "mini ice age" on Earth that lasted a few years. It was nothing comparable to the last real ice age though, and the current solar minimum is nothing close to the Maunder minimum.

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Re: 51 Pegasi - Maunder minimum candidate?

Post by Lazarus on 26th November 2009, 2:50 pm

Maybe the Maunder Minimum caused one of the minima of the "little ice age", maybe it didn't. The coincidental timing is somewhat suspicious though.

Possibly this suggests that 51 Peg b isn't an especially magnetic planet... contrasts to, say, Ups And b and HD 177949b which appear to be associated with active regions on their parent stars.
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Re: 51 Pegasi - Maunder minimum candidate?

Post by Sirius_Alpha on 26th November 2009, 3:28 pm

That may bode well for the planet candidates status as a bona fide planet. I would expect a massive planet to bother its star more.

Whatever happened to that possible detection of transits of 51 Peg b's evaporation tail? Are they still awaiting HST STIS spectroscopy to confirm?

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