An investigation of chromospheric activity spanning the Vaughan--Preston gap: impact on stellar ages Export

@article{citeulike:4470265, abstract = {Chromospheric activity is widely used as an age indicator for solar-type stars based on the early evidence that there is a smooth evolution from young and active to old and inactive stars. We analysed chromospheric activity in five solar-type stars in two open clusters, in order to study how chromospheric activity evolves with time. We took UVES high-resolution, high S/N ratio spectra of 3 stars in IC 4756 and 2 in NGC 5822, which were combined with a previously studied data-set and reanalysed here. The emission core of the deep, photospheric Ca II K line was used as a probe of the chromospheric activity. All of the 5 stars in the new sample, including those in the 1.2 Gyr-old NGC 5822, have activity levels comparable to those of Hyades and Praesepe. A likely interpretation of our data is that solar-type-star chromospheric activity, from the age of the Hyades until that of the Sun, does not evolve smoothly. Stars change from active to inactive on a short timescale. Evolution before and after such a transition is much less significant than cyclical and long-term variations. We show that data presented in the literature to support a correlation between age and activity could be also interpreted differently in the light of our results.}, archivePrefix = {arXiv}, author = {Pace, G. and Melendez, J. and Pasquini, L. and Carraro, G. and Danziger, J. and Francois, P. and Matteucci, F. and Santos, N. C.}, citeulike-article-id = {4470265}, citeulike-linkout-0 = {http://arxiv.org/abs/0904.3199}, citeulike-linkout-1 = {http://arxiv.org/pdf/0904.3199}, day = {22}, eprint = {0904.3199}, keywords = {age-activity-rotation-relationship}, month = {Apr}, posted-at = {2009-10-23 20:49:22}, priority = {2}, title = {An investigation of chromospheric activity spanning the Vaughan\&\#45;\&\#45;Preston gap: impact on stellar ages}, url = {http://arxiv.org/abs/0904.3199}, year = {2009} }

TY - JOUR ID - citeulike:4470265 L3 - citeulike-article-id:4470265 N2 - Chromospheric activity is widely used as an age indicator for solar-type stars based on the early evidence that there is a smooth evolution from young and active to old and inactive stars. We analysed chromospheric activity in five solar-type stars in two open clusters, in order to study how chromospheric activity evolves with time. We took UVES high-resolution, high S/N ratio spectra of 3 stars in IC 4756 and 2 in NGC 5822, which were combined with a previously studied data-set and reanalysed here. The emission core of the deep, photospheric Ca II K line was used as a probe of the chromospheric activity. All of the 5 stars in the new sample, including those in the 1.2 Gyr-old NGC 5822, have activity levels comparable to those of Hyades and Praesepe. A likely interpretation of our data is that solar-type-star chromospheric activity, from the age of the Hyades until that of the Sun, does not evolve smoothly. Stars change from active to inactive on a short timescale. Evolution before and after such a transition is much less significant than cyclical and long-term variations. We show that data presented in the literature to support a correlation between age and activity could be also interpreted differently in the light of our results. TI - An investigation of chromospheric activity spanning the Vaughan--Preston gap: impact on stellar ages KW - age-activity-rotation-relationship AU - Pace, G AU - Melendez, J AU - Pasquini, L AU - Carraro, G AU - Danziger, J AU - Francois, P AU - Matteucci, F AU - Santos, NC PY - 2009/Apr/22/ UR - http://arxiv.org/abs/0904.3199 ER -