文章基本信息

标题：Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system
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作者：Ruben Asensio-Torres ; Thayne Currie ; Markus Janson 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：622
DOI：10.1051/0004-6361/201834688
语种：English
出版社：EDP Sciences
摘要：We present SCExAO/CHARIS 1.1–2.4μm integral field direct spectroscopy of the young HIP 79124 triple system. HIP 79124 is a member of the Scorpius-Centaurus association, consisting of an A0V primary with two low-mass companions at a projected separation of < 1″. Thanks to the high quality wavefront corrections provided by SCExAO, both companions are decisively detected without the employment of any PSF-subtraction algorithm to eliminate quasi-static noise. The spectrum of the outer C object is very well matched by Upper Scorpius M4 ± 0.5 standard spectra, with aTeff = 2945 ± 100 K and a mass of ∼350MJup. HIP 79124 B is detected at a separation of only 180 mas in a highly-correlated noise regime, and it falls in the spectral range M6 ± 0.5 withTeff = 2840 ± 190 K and ∼100MJup. Previous studies of stellar populations in Sco-Cen have highlighted a discrepancy in isochronal ages between the lower-mass and higher-mass populations. This could be explained either by an age spread in the region, or by conventional isochronal models failing to reproduce the evolution of low-mass stars. The HIP 79124 system should be coeval, and therefore it provides an ideal laboratory to test these scenarios. We place the three components in a color–magnitude diagram and find that the models predict a younger age for the two low-mass companions (∼3 Myr) than for the primary star (∼6 Myr). These results imply that the omission of magnetic effects in conventional isochronal models inhibit them from reproducing early low-mass stellar evolution, which is further supported by the fact that new models that include such effects provide more consistent ages in the HIP 79124 system.
关键词：enbinaries: closestars: low-massstars: pre-main sequencetechniques: imaging spectroscopyplanets and satellites: detection