The chromospheric emission of solar-type stars in the young open clusters IC 2391 and IC 2602

Marsden, S. C. and Carter, B. D. and Donati, J.-F. (2009) The chromospheric emission of solar-type stars in the young open clusters IC 2391 and IC 2602. Monthly Notices of the Royal Astronomical Society, 399 (2). pp. 888-905. ISSN 0035-8711

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Abstract

In this paper we present chromospheric emission levels of the solar-type stars in the young open clusters IC 2391 and IC 2602. High-resolution spectroscopic data were obtained for over 50 F, G and K stars from these clusters over several observing campaigns using the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Unlike older clusters, the majority (28/52) of the solar-type stars in the two clusters are rapid rotators (v sin i > 20 km s−1) with five of the stars being classified as ultra-rapid rotators (v sin i > 100 km s−1) . The emission levels in the calcium infrared triplet lines were then used as a measure of the chromospheric activity of the stars. When plotted against the Rossby number (NR), the star's chromospheric emission levels show a plateau in the emission for log(NR) ≲−1.1 indicating chromospheric saturation similar to the coronal saturation seen in previously observed X-ray emission from the same stars. However, unlike the coronal emission, the chromospheric emission of the stars shows little evidence of a reduction in emission (i.e. supersaturation) for the ultra-rapid rotators in the clusters. Thus we believe that coronal supersaturation is not the result of an overall decrease in magnetic dynamo efficiency for ultra-rapid rotators.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Pre-print template-style version deposited in accordance with the copyright policy of the publisher. The definitive version is available at www.blackwell-synergy.com.
Depositing User: Dr Brad Carter
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 17 Feb 2010 05:26
Last Modified: 02 Jul 2013 23:25
Uncontrolled Keywords: stars; activity; late-type; rotation; open clusters and associations; individual; IC 2391; IC 2602
Fields of Research (FOR2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
04 Earth Sciences > 0401 Atmospheric Sciences > 040108 Tropospheric and Stratospheric Physics
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: doi: 10.1111/j.1365-2966.2009.15319.x
URI: http://eprints.usq.edu.au/id/eprint/5767

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