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|Title:||Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system||Authors:||Asensio-Torres, Ruben
Brandt, Timothy D.
|Issue Date:||2019||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||622||First Page:||A42||Abstract:||We present SCExAO/CHARIS 1.1-2.4 μm 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 a T<SUB>eff</SUB> = 2945 ± 100 K and a mass of ∼350 M<SUB>Jup</SUB>. 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 with T<SUB>eff</SUB> = 2840 ± 190 K and ∼100 M<SUB>Jup</SUB>. 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.||URI:||http://hdl.handle.net/20.500.12386/29410||URL:||https://www.aanda.org/articles/aa/full_html/2019/02/aa34688-18/aa34688-18.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201834688||Bibcode ADS:||2019A&A...622A..42A||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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