A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Doppler imaging of stellar surface structure XXIV. The lithium-rich single K-giants DP Canum Venaticorum and DI Piscium
Alaotsikko: XXIV. The lithium-rich single K-giants DP Canum Venaticorum and DI Piscium
Tekijät: Kővári Zs, Korhonen H, Strassmeier K G, Weber M, Kriskovics L, Savanov I
Kustantaja: EDP Sciences
Julkaisuvuosi: 2013
Journal: Astronomy and Astrophysics
Lehden akronyymi: A&A
Artikkelin numero: A2
Vuosikerta: 551
Sivujen määrä: 11
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201220227
Verkko-osoite: http://dx.doi.org/10.1051/0004-6361/201220227
Tiivistelmä
Aims: We present the first Doppler imaging study of the two rapidly rotating, single K-giants DP CVn and DI Psc in order to study the surface spot configuration and to pinpoint their stellar evolutionary status.
Methods: Optical spectroscopy and photometry were used to determine the fundamental astrophysical properties. Doppler imaging was applied to recover the surface temperature distribution for both stars, while photometric light-curve inversions were carried out for studying the long-term changes of the surface activity of DP CVn. Surface differential rotation of DP CVn was estimated from cross-correlating the available subsequent Doppler reconstructions separated by roughly one rotation period.
Results: Both stars appear to have higher than normal lithium abundance, LTE log n of 2.28 (DP CVn) and 2.20 (DI Psc), and are supposed to be located at the end of the first Li dredge-up on the RGB. Photometric observations reveal rotational modulation with a period of 14.010 d (DP CVn) and 18.066 d (DI Psc). Doppler reconstructions from the available mapping lines well agree in the revealed spot patterns, recovering rather low latitude spots for both stars with temperature contrasts of ΔT ≈ 600-800 K below the unspotted photospheric background. Spots at higher latitudes are also found but either with less contrast (DP CVn) or with smaller extent (DI Psc). A preliminary antisolar-type differential rotation with α = -0.035 is found for DP CVn from cross-correlating the subsequent Doppler images. Long-term photometric analysis supports the existence of active longitudes, as well as the differential rotation.
Aims: We present the first Doppler imaging study of the two rapidly rotating, single K-giants DP CVn and DI Psc in order to study the surface spot configuration and to pinpoint their stellar evolutionary status.
Methods: Optical spectroscopy and photometry were used to determine the fundamental astrophysical properties. Doppler imaging was applied to recover the surface temperature distribution for both stars, while photometric light-curve inversions were carried out for studying the long-term changes of the surface activity of DP CVn. Surface differential rotation of DP CVn was estimated from cross-correlating the available subsequent Doppler reconstructions separated by roughly one rotation period.
Results: Both stars appear to have higher than normal lithium abundance, LTE log n of 2.28 (DP CVn) and 2.20 (DI Psc), and are supposed to be located at the end of the first Li dredge-up on the RGB. Photometric observations reveal rotational modulation with a period of 14.010 d (DP CVn) and 18.066 d (DI Psc). Doppler reconstructions from the available mapping lines well agree in the revealed spot patterns, recovering rather low latitude spots for both stars with temperature contrasts of ΔT ≈ 600-800 K below the unspotted photospheric background. Spots at higher latitudes are also found but either with less contrast (DP CVn) or with smaller extent (DI Psc). A preliminary antisolar-type differential rotation with α = -0.035 is found for DP CVn from cross-correlating the subsequent Doppler images. Long-term photometric analysis supports the existence of active longitudes, as well as the differential rotation.
Turun yliopiston Tutkimustietojärjestelmän portaali