Cycles are most often found among moderately active stars. (1995) find that ~60% of the main-sequence stars with spectral types from F to early M show cycles with periods in the range 2.5–25 yr. Table 2 is available in electronic form at Īctivity cycles are commonly found among late-type stars through chromospheric indicators, such as the Mount Wilson Ca ii H&K S-index. This cycle is probably representative of the first coronal cycles in the life of a solar-like star, at the age when life started on Earth. The 1.6 yr cycle is the shortest coronal one observed to date, and ι Hor represents the most active star for which a coronal activity cycle has been found. It is likely subject to the modulation of a longer, not yet constrained second cycle. We confirm the presence of an activity cycle of ~1.6 yr in ι Hor both in X-rays and Ca ii H&K.
The second cycle is disrupted prior to reaching its maximum, followed by a brief episode of chaotic variability before the cyclic behavior resumes, only to be disrupted again after slightly more than one cycle.Ĭonclusions. The continuous chromospheric monitoring for more than three cycle lengths shows a trend toward decreasing amplitude, apparently modulated by a longer term trend. We find a cyclic behavior in X-rays very similar to the contemporaneous chromospheric cycle. The spectra of each observation are fit with two-temperature coronal models to study the long-term variability of the star. We monitored ι Hor with XMM-Newton observations spanning almost two years. This represents the first X-ray cycle observed in an active star, as well as the paradigm of the first coronal cycles in the life of a solar-like star. We intended to find the X-ray coronal counterpart of the chromospheric cycle for ι Hor. Coronal X-ray activity cycles have only been discovered in a few stars other than the Sun, all of them with an older age and a lower activity level than ι Hor.Īims. The shortest chromospheric (Ca ii H&K) activity cycle (1.6 yr) has been recently discovered in the young (~600 Myr) solar-like star ι Hor. Vaiana, Piazza del Parlamento 1, 90134 Palermo, ItalyĮ-mail: Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USAĮ-mail: Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, DenmarkĬontext. Metcalfe 3 ,4ġ Departamento de Astrofísica, Centro de Astrobiología (CSIC–INTA), ESAC Campus, PO Box 78, 28691 Villanueva de la Cañada, Madrid, SpainĮ-mail: INAF – Osservatorio Astronomico di Palermo G. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes In Methodology of frontal and executive function (pp. Behavioural assessment of the Dysexecutive syndrome. Fractionation of the dysexecutive syndrome in a heterogeneous neurological sample: Comparing the dysexecutive questionnaire and the Brock adaptive functioning questionnaire. British Journal of Psychology, 92(3), 551.Ĭhaytor, N., & Schmitter-Edgecombe, M. Dysexecutive symptoms among a non-clinical sample: A study with the use of the dysexecutive questionnaire. Neuropsychological Rehabilitation, 11(5), 529–537.Ĭhan, R. A comparison of the validity of self-report measures amongst people with acquired brain injury: A preliminary study of the usefulness of EuroQol-5D. Alderman, N., Dawson, K., Rutterford, N., & Reynolds, P.