Siklus Starspot Terpendek Pada Sistem Bintang Iota Horologii

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KeSimpulan.com - Siklus starspot terpendek. Planet-planet mengorbit Iota Horologii hanya menikmati respites singkat dari matahari menggelora mereka.

Bintang yang terletak 56 tahun cahaya di konstelasi Horologium selatan, memiliki siklus starspot terpendek yang pernah terlihat yaitu 1,6 tahun. Siklus sunspot Matahari kita sendiri, bertambah dan berkurang setiap 11 tahun. Ketika sunspot mencapai puncak, sinar Matahari bisa melemparkan flare ke arah satelit pengorbit untuk menggoreng planet Bumi.

Dengan demikian setiap penduduk di sistem Iota Horologii yang setidaknya tanpa ampun menimpa pada salah satu planet raksasa dimana mungkin mengalami ledakan lebih sering, para astronom telah mengirim ke server preprint arXiv untuk dipublikasikan di edisi mendatang The Astrophysical Journal Letters:

The Mount Wilson Ca HK survey revealed magnetic activity variations in a large sample of solar-type stars with timescales ranging from 2.5 to 25 years. This broad range of cycle periods is thought to reflect differences in the rotational properties and the depths of the surface convection zones for stars with various masses and ages. In 2007 we initiated a long-term monitoring campaign of Ca II H and K emission for a sample of 57 southern solar-type stars to measure their magnetic activity cycles and their rotational properties when possible. We report the discovery of a 1.6-year magnetic activity cycle in the exoplanet host star iota Horologii, and we obtain an estimate of the rotation period that is consistent with Hyades membership. This is the shortest activity cycle so far measured for a solar-type star, and may be related to the short-timescale magnetic variations recently identified in the Sun and HD49933 from helio- and asteroseismic measurements. Future asteroseismic observations can be compared to those obtained near the magnetic minimum in 2006 to search for cycle-induced shifts in the oscillation frequencies. If such short activity cycles are common in F stars, then NASA's Kepler mission should observe their effects in many of its long-term asteroseismic targets.

Kondisi serupa mungkin telah dialami di Bumi selama perjuangan kehidupan untuk membangun sendiri ketika Matahari kita masih muda. Pada saat itu, Matahari akan menyerupai Iota Horologii, karena bintang itu masih muda yang diperkirakan telah melarikan diri dari cluster bintang Hyades yang hanya berjarak 600 juta tahun.
  1. T.S. Metcalfe, S. Basu, T.J. Henry, D.R. Soderblom, P.G. Judge, M. Knoelker, S. Mathur, M. Rempel. Discovery of a 1.6-year Magnetic Activity Cycle in the Exoplanet Host Star iota Horologii. arXiv:1009.5399 [astro-ph.SR], 1 Oct 2010.
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