Issue |
A&A
Volume 622, February 2019
|
|
---|---|---|
Article Number | A42 | |
Number of page(s) | 13 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/201834688 | |
Published online | 24 January 2019 |
Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system
1
Department of Astronomy, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
e-mail: ruben.torres@astro.su.se
2
NASA-Ames Research Center, Moffett Field, California 94035, USA
3
National Astronomical Observatory of Japan, Subaru Telescope, National Institutes of Natural Sciences, Hilo, HI 96720, USA
4
Eureka Scientific, 2452 Delmer Street Suite 100. Oakland, CA 94602-3017, USA
5
INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
6
Astrobiology Center, National Institutes of Natural Sciences, 2-21-1 Osawa Mitaka, Tokyo, Japan
7
National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
8
Institute for Astronomy, University of Hawaii, Hilo, HI, USA
9
Department of Physics, University of California-Santa Barbara, Santa Barbara, CA, USA
10
Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
11
College of Optical Sciences, University of Arizona, Tucson, AZ 85721, USA
12
NASA-Goddard Space Flight Center, Greenbelt, MD, USA
13
Department of Mechanical Engineering, Princeton University, Princeton, NJ, USA
14
Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall Notre Dame, IN 46556, USA
15
Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
16
Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
17
Center for Extrasolar Planetary Systems, Space Science Institute, 1120 Paxton Ave., Cincinnati, OH 45208, USA
18
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
19
Institute for the Advancement of Higher Education, Hokkaido University, Kita 17, Nishi 8, Kita-ku, Sapporo 060-0817, Japan
20
ISAS/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan
21
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
22
Department of Astronomy, The Graduate University for Advanced Studies, National Astronomical Observatory of Japan, Japan
23
Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
24
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Received:
20
November
2018
Accepted:
18
December
2018
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.
Key words: binaries: close / stars: low-mass / stars: pre-main sequence / techniques: imaging spectroscopy / planets and satellites: detection
© ESO 2019
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