Solar and Stellar Flares over Time: Effects on Hosted Planets
Abstract
The effects of flares from the Sun on Earth and other solar-system planets are presented. Also discussed are the flare properties of cooler, commonplace main-sequence K-M stars. Data from our "Sun in Time" program are used to study the flare properties of the Sun and solar-type stars from youth to old age. These studies are based on ground-based observations, UV and X-ray space missions (IUE & HST, ROSAT & Chandra) as well as a wealth of data from the Kepler Mission. The ultra-high precision photometry available from the Kepler Mission (and K2) has made it possible to study starspots, flare properties, and rotations of thousands of G, K, M stars. Superflares (defined as E > 10+33 ergs ~X-100 flares) on hundreds of mostly G and K stars have been found. (See e.g. Shibayama et al. 2013; Maehara et al. 2015; Notsu et al. 2013/15; Saar et al. 2015; Guinan et al. 2015). Using our Age-Rotation relations, we determine correlations of flares properties of the Sun and solar-type over a wide range of ages. We also compare these flare histories with the cooler, more common K- and M-type stars. The analysis of these datasets imply that the young Sun had numerous, very powerful flares that may have played major roles the evolution of the early atmospheres of Earth and other terrestrial planets. The strong X-UV fluxes and proton fluences from flares and associated plasmas from coronal mass ejection events can greatly affect the photochemistry of planetary atmospheres as well as ionizing and possibly eroding their atmospheres. Some examples are given. Also discussed are the effects of superflares from the present Sun on the Earth. Even though solar superflares are rarer (~1 per 300-500 yrs) than from the young Sun (> 1-2 per year), they could cause significant damage to our communication and satellite systems, electrical networks, and threaten the lives of astronauts in space..This research is supported by grants from NSF/RUI and NASA: NSF, AST 1009903; Chandra GO2-13020X, HST GO-13020.01. We are very grateful for this support
- Publication:
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American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016
- Bibcode:
- 2016AAS...22740605G