On the isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system. (arXiv:1811.10684v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Asensio_Torres_R/0/1/0/all/0/1">Ruben Asensio-Torres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Currie_T/0/1/0/all/0/1">Thayne Currie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Janson_M/0/1/0/all/0/1">Markus Janson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Desidera_S/0/1/0/all/0/1">Silvano Desidera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuzuhara_M/0/1/0/all/0/1">Masayuki Kuzuhara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hodapp_K/0/1/0/all/0/1">Klaus Hodapp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_T/0/1/0/all/0/1">Timothy D. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guyon_O/0/1/0/all/0/1">Olivier Guyon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lozi_J/0/1/0/all/0/1">Julien Lozi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Groff_T/0/1/0/all/0/1">Tyler Groff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kasdin_J/0/1/0/all/0/1">Jeremy Kasdin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chilcote_J/0/1/0/all/0/1">Jeffrey Chilcote</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jovanovic_N/0/1/0/all/0/1">Nemanja Jovanovic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinache_F/0/1/0/all/0/1">Frantz Martinache</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sitko_M/0/1/0/all/0/1">Michael Sitko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Serabyn_E/0/1/0/all/0/1">Eugene Serabyn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wagner_K/0/1/0/all/0/1">Kevin Wagner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Akiyama_E/0/1/0/all/0/1">Eiji Akiyama</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kwon_J/0/1/0/all/0/1">Jungmi Kwon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uyama_T/0/1/0/all/0/1">Taichi Uyama</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Yi Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nakagawa_T/0/1/0/all/0/1">Takao Nakagawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayashi_M/0/1/0/all/0/1">Masahiko Hayashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McElwain_M/0/1/0/all/0/1">Michael McElwain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kudo_T/0/1/0/all/0/1">Tomoyuki Kudo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tamura_M/0/1/0/all/0/1">Motohide Tamura</a>

We present SCExAO/CHARIS 1.1–2.4 micron 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 arcsecond. 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 pm 0.5 standard spectra, with a Teff = 2945 pm 100 and a mass of 350 MJup. 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 pm 0.5 with Teff = 2840 pm 190 and 100 MJup. Previous studies of stellar populations in Sco-Cen have highlighted a discrepancy in isochronal ages between the low-mass and high-mass populations. This could be explained either by a mass-dependent age gradient 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.

We present SCExAO/CHARIS 1.1–2.4 micron 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 arcsecond. 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 pm 0.5 standard spectra, with a Teff = 2945 pm 100
and a mass of 350 MJup. 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 pm
0.5 with Teff = 2840 pm 190 and 100 MJup. Previous studies of stellar
populations in Sco-Cen have highlighted a discrepancy in isochronal ages
between the low-mass and high-mass populations. This could be explained either
by a mass-dependent age gradient 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.

http://arxiv.org/icons/sfx.gif