Abstract
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 language | English |
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Pages (from-to) | 1417-1421 |
Journal | Astronomy & Astrophysics |
Volume | 508 |
Issue number | 3 1417 |
Publication status | Published - 01 Dec 2009 |
Keywords
- stars: coronae
- stars: activity
- stars: individual: 51 Peg
- X-rays: stars
- X-rays: individuals: 51 Peg