There are 4290 abstracts currently viewable. Search: Advanced Search
* News 04/04/20 * The archive is using a new backend database. This has thrown up a few SQL errors in the last few days. If you have any issues please email adavey@nso.edu with either the number of eprint you are trying to edit or a link to your preprint.

 High Dispersion Spectroscopy of Solar-type Superflare Stars. I. Temperature, Surface Gravity, Metallicity, and v \sin i Yuta Notsu   Submitted: 2014-12-29 19:04 We conducted high dispersion spectroscopic observations of 50 superflare stars with Subaru/HDS, and measured the stellar parameters of them. These 50 targets were selected from the solar-type (G-type main sequence) superflare stars that we had discovered from the Kepler photometric data. As a result of these spectroscopic observations, we found that more than half (34 stars) of our 50 targets have no evidence of binary system. We then estimated effective temperature (T{eff}), surface gravity (log g), metallicity ([Fe/H]), and projected rotational velocity (v\sin i) of these 34 superflare stars on the basis of our spectroscopic data. The accuracy of our estimations is higher than that of Kepler Input Catalog (KIC) values, and the differences between our values and KIC values ((Δ T{eff}){rms} ~ 219K, (Δ log g){rms} ~ 0.37 dex, and (Δ{[Fe/H]}){rms} ~ 0.46 dex) are comparable to the large uncertainties and systematic differences of KIC values reported by the previous researches. We confirmed that the estimated T{eff} and log g values of the 34 superflare stars are roughly in the range of solar-type stars. In particular, these parameters and the brightness variation period (P0) of 9 stars are in the range of Sun-like" stars (5600≤ T{eff}≤ 6000K, log g≥4.0, and P0>10 days). Five of the 34 target stars are fast rotators (v \sin i ≥ 10km s-1), while 22 stars have relatively low v \sin i values (v \sin i<5km s-1). These results suggest that stars whose spectroscopic properties similar to the Sun can have superflares, and this supports the hypothesis that the Sun might cause a superflare. Authors: Yuta Notsu, Satoshi Honda, Hiroyuki Maehara, Shota Notsu, Takuya Shibayama, Daisaku Nogami, Kazunari Shibata Projects: Other