Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system

Ruben Asensio-Torres, Thayne Currie, Markus Janson, Silvano Desidera, Masayuki Kuzuhara, Klaus Hodapp, Timothy D. Brandt, Olivier Guyon, Julien Lozi, Tyler Groff, Jeremy Kasdin, Jeffrey Chilcote, Nemanja Jovanovic, Frantz Martinache, Michael Sitko, Eugene Serabyn, Kevin Wagner, Eiji Akiyama, Jungmi Kwon, Taichi UyamaYi Yang, Takao Nakagawa, Masahiko Hayashi, Michael McElwain, Tomoyuki Kudo, Thomas Henning, Motohide Tamura

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20 Scopus citations


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 eff = 2945 ± 100 K and a mass of ∼350 M Jup . 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 eff = 2840 ± 190 K and ∼100 M Jup . 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.

Original languageEnglish (US)
Article numberA42
JournalAstronomy and Astrophysics
StatePublished - Feb 1 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Binaries: close
  • Planets and satellites: detection
  • Stars: low-mass
  • Stars: pre-main sequence
  • Techniques: imaging spectroscopy


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