51 Pegasi - a planet-bearing Maunder minimum candidate

K. Poppenhäger, J. Robrade, J. H. M. M. Schmitt, J. C. Hall, Katja Poppenhaeger

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16 Citations (Scopus)


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⪉ 1 MK; the detected ACIS-S photons can be plausibly explained by emission lines of a very cool plasma near 200 eV. The constantly low X-ray surface flux and the flat-activity profile seen in optical Ca II 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 200 eV than given in the calibration.
Original languageEnglish
Pages (from-to)1417-1421
JournalAstronomy & Astrophysics
Issue number3 1417
Publication statusPublished - 01 Dec 2009


  • stars: coronae
  • stars: activity
  • stars: individual: 51 Peg
  • X-rays: stars
  • X-rays: individuals: 51 Peg


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