Stars of stellar type later than about M3.5 are believed to be fully
convective and therefore unable to support magnetic dynamos like the one that
produces the 11-year solar cycle. Because of their intrinsic faintness, very
few late M stars have undergone long-term monitoring to test this prediction,
which is critical to our understanding of magnetic field generation in such
stars. Magnetic activity is also of interest as the driver of UV and X-ray
radiation, as well as energetic particles and stellar winds, that affect the
atmospheres of close-in planets that lie within habitable zones, such as the
recently discovered Proxima b. We report here on several years of optical, UV,
and X-ray observations of Proxima Centauri (GJ 551; dM5.5e): 15 years of ASAS
photometry in the V band (1085 nights) and 3 years in the I band (196 nights),
4 years of Swift XRT and UVOT observations (more than 120 exposures), and 9
sets of X-ray observations from other X-ray missions (ASCA, XMM-Newton, and
three Chandra instruments) spanning 22 years. We confirm previous reports of an
83-day rotational period and find strong evidence for a 7-year stellar cycle,
along with indications of differential rotation at about the solar level.
X-ray/UV intensity is anti-correlated with optical V-band brightness for both
rotational and cyclical variations. From comparison with other stars observed
to have X-ray cycles we deduce a simple empirical relationship between X-ray
cyclic modulation and Rossby number, and we also present Swift UV grism spectra
covering 2300-6000 \AA.
%0 Journal Article
%1 citeulike:14170074
%A Wargelin, B. J.
%A Saar, S. H.
%A Pojmański, G.
%A Drake, J. J.
%A Kashyap, V. L.
%D 2016
%J Monthly Notices of the Royal Astronomical Society
%K imported
%P stw2570+
%R 10.1093/mnras/stw2570
%T Optical, UV, and X-Ray Evidence for a 7-Year Stellar Cycle in Proxima Centauri
%U http://dx.doi.org/10.1093/mnras/stw2570
%X Stars of stellar type later than about M3.5 are believed to be fully
convective and therefore unable to support magnetic dynamos like the one that
produces the 11-year solar cycle. Because of their intrinsic faintness, very
few late M stars have undergone long-term monitoring to test this prediction,
which is critical to our understanding of magnetic field generation in such
stars. Magnetic activity is also of interest as the driver of UV and X-ray
radiation, as well as energetic particles and stellar winds, that affect the
atmospheres of close-in planets that lie within habitable zones, such as the
recently discovered Proxima b. We report here on several years of optical, UV,
and X-ray observations of Proxima Centauri (GJ 551; dM5.5e): 15 years of ASAS
photometry in the V band (1085 nights) and 3 years in the I band (196 nights),
4 years of Swift XRT and UVOT observations (more than 120 exposures), and 9
sets of X-ray observations from other X-ray missions (ASCA, XMM-Newton, and
three Chandra instruments) spanning 22 years. We confirm previous reports of an
83-day rotational period and find strong evidence for a 7-year stellar cycle,
along with indications of differential rotation at about the solar level.
X-ray/UV intensity is anti-correlated with optical V-band brightness for both
rotational and cyclical variations. From comparison with other stars observed
to have X-ray cycles we deduce a simple empirical relationship between X-ray
cyclic modulation and Rossby number, and we also present Swift UV grism spectra
covering 2300-6000 \AA.
@article{citeulike:14170074,
abstract = {Stars of stellar type later than about M3.5 are believed to be fully
convective and therefore unable to support magnetic dynamos like the one that
produces the 11-year solar cycle. Because of their intrinsic faintness, very
few late M stars have undergone long-term monitoring to test this prediction,
which is critical to our understanding of magnetic field generation in such
stars. Magnetic activity is also of interest as the driver of UV and X-ray
radiation, as well as energetic particles and stellar winds, that affect the
atmospheres of close-in planets that lie within habitable zones, such as the
recently discovered Proxima b. We report here on several years of optical, UV,
and X-ray observations of Proxima Centauri (GJ 551; dM5.5e): 15 years of ASAS
photometry in the V band (1085 nights) and 3 years in the I band (196 nights),
4 years of Swift XRT and UVOT observations (more than 120 exposures), and 9
sets of X-ray observations from other X-ray missions (ASCA, XMM-Newton, and
three Chandra instruments) spanning 22 years. We confirm previous reports of an
83-day rotational period and find strong evidence for a 7-year stellar cycle,
along with indications of differential rotation at about the solar level.
X-ray/UV intensity is anti-correlated with optical V-band brightness for both
rotational and cyclical variations. From comparison with other stars observed
to have X-ray cycles we deduce a simple empirical relationship between X-ray
cyclic modulation and Rossby number, and we also present Swift UV grism spectra
covering 2300-6000 {\AA}.},
added-at = {2019-03-25T08:20:55.000+0100},
archiveprefix = {arXiv},
author = {Wargelin, B. J. and Saar, S. H. and Pojma\'{n}ski, G. and Drake, J. J. and Kashyap, V. L.},
biburl = {https://www.bibsonomy.org/bibtex/2a2830e2d3d3d6f3d0be445f4e06ad99f/ericblackman},
citeulike-article-id = {14170074},
citeulike-linkout-0 = {http://arxiv.org/abs/1610.03447},
citeulike-linkout-1 = {http://arxiv.org/pdf/1610.03447},
citeulike-linkout-2 = {http://dx.doi.org/10.1093/mnras/stw2570},
day = 11,
doi = {10.1093/mnras/stw2570},
eprint = {1610.03447},
interhash = {c0a76d63b4c85e3c20d4260027002120},
intrahash = {a2830e2d3d3d6f3d0be445f4e06ad99f},
issn = {0035-8711},
journal = {Monthly Notices of the Royal Astronomical Society},
keywords = {imported},
month = oct,
pages = {stw2570+},
posted-at = {2016-10-22 07:29:54},
priority = {2},
timestamp = {2019-03-25T08:20:55.000+0100},
title = {{Optical, UV, and X-Ray Evidence for a 7-Year Stellar Cycle in Proxima Centauri}},
url = {http://dx.doi.org/10.1093/mnras/stw2570},
year = 2016
}