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

Ruben Asensio-Torres (1) , Thayne Currie (2) , Markus Janson (3) , Silvano Desidera (4) , Masayuki Kuzuhara (2) , Klaus Hodapp (5) , Timothy Brandt (6) , Olivier Guyon (7) , Julien Lozi (2) , Tyler Groff (8) , Jeremy Kasdin (9) , Jeffrey Chilcote (10) , Nemanja Jovanovic (11) , Frantz Martinache (12) , Michael Sitko (13) , Eugene Serabyn (14) , Kevin Wagner (15) , Eiji Akiyama (16) , Jungmi Kwon (17) , Taichi Uyama (18) , Yi Yang (19) , Takao Nakagawa , Masahiko Hayashi (20) , Michael Mcelwain (8) , Tomoyuki Kudo (2) , Thomas Henning (21) , Motohide Tamura (2)

1 Stockholm University
2 NAOJ - National Astronomical Observatory of Japan
3 MPIA - Max-Planck-Institut für Astronomie
4 OAPD - INAF - Osservatorio Astronomico di Padova
5 University of Hawaii
6 UC Santa Barbara - University of California [Santa Barbara]
7 SFL-ENSMSE - Département Sciences de la Fabrication et Logistique
8 NASA
9 Princeton University
10 UND - University of Notre Dame [Indiana]
11 CALTECH - California Institute of Technology
12 LAGRANGE - Joseph Louis LAGRANGE
13 Space Science Institute
14 JPL - Jet Propulsion Laboratory
15 University of Arizona
16 Hokkaido University [Sapporo, Japan]
17 ISAS - Institute of Space and Astronautical Science
18 UTokyo - The University of Tokyo
19 SPL - Signal Processing Laboratory
20 ESST - Department of Earth System Science and Technology [Fukuoka]
21 D-INFK - Department of Computer Science [ETH Zürich]

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 Teff = 2945 ± 100 K 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 ± 0.5 with Teff = 2840 ± 190 K and ∼100 MJup. 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.

Mots clés: binaries: close; stars: low-mass; stars: pre-main sequence; techniques: imaging spectroscopy; planets and satellites: detection

Domaines: Physique [physics]; Astrophysique [astro-ph]; Astrophysique [astro-ph]

Ruben Asensio-Torres, Thayne Currie, Markus Janson, Silvano Desidera, Masayuki Kuzuhara, et al.. Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system. Astronomy and Astrophysics - A&A, 2019, 622, pp.A42. ⟨10.1051/0004-6361/201834688⟩. ⟨hal-02303350⟩