E-Print Archive

There are 3882 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
High Dispersion Spectroscopy of the Superflare Star KIC6934317  

Shota Notsu   Submitted: 2013-07-18 22:13

We conducted the high-resolution spectroscopic observation with Subaru/HDS for a G-type star (KIC6934317). We selected this star from the data of the Kepler spacecraft. This star produces a lot of superflares, and the total energy of the largest superflare on this star is ~103 times larger (~2.2*1035 erg) than that of the most energetic flare on the Sun (~1032 erg). The core depth and emission flux of Ca II infrared triplet lines and Ha line show high chromospheric activity in this star, in spite of its low lithium abundance and the small amplitude of the rotational modulation. Using the empirical relations between emission flux of chromospheric lines and X-ray flux, this star is considered to show much higher coronal activity than that of the Sun. It probably has large starspots which can store a large amount of magnetic energy enough to give rise to superflares. We also estimated the stellar parameters, such as effective temperature, surface gravity, metallicity, projected rotational velocity (v sin_i), and radial velocity. KIC6934317 is then confirmed to be an early G-type main sequence star. The value of v sin_i is estimated to be ~1.91 km s-1. In contrast, the rotational velocity is calculated to be ~20 km s-1 by using the period of the brightness variation as the rotation period. This difference can be explained by its small inclination angle (nearly pole-on). The small inclination angle is also supported by the contrast between the large superflare amplitude and the small stellar brightness variation amplitude. The lithium abundance and isochrones implies that the age of this star is more than about a few Gyr, though a problem why this star with such an age has a strong activity remains unsolved.

Authors: Shota Notsu, Satoshi Honda, Yuta Notsu, Takashi Nagao, Takuya Shibayama, Hiroyuki Maehara, Daisaku Nogami, Kazunari Shibata
Projects: None

Publication Status: Accepted by Publications of the Astronomical Society of Japan (PASJ) on July 18, 2013 (to be published on PASJ vol. 65, No. 5 (October 25, 2013)).
Last Modified: 2013-07-19 10:34
Go to main E-Print page  Edit Entry  Download Preprint  Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
High Dispersion Spectroscopy of the Superflare Star KIC6934317

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2003 Solar Physics Group - Montana State University