K. G. Hełminiak, M. Kuzuhara, K. Mede, T. D. Brandt, R. Kandori, T. Suenaga, N. Kusakabe, N. Narita, J. C. Carson, T. Currie, T. Kudo, J. Hashimoto, L. Abe, E. Akiyama, W. Brandner, M. Feldt, M. Goto, C. A. Grady, O. Guyon, Y. HayanoM. Hayashi, S. S. Hayashi, T. Henning, K. W. Hodapp, M. Ishii, M. Iye, M. Janson, G. R. Knapp, J. Kwon, T. Matsuo, M. W. McElwain, S. Miyama, J. I. Morino, A. Moro-Martin, T. Nishimura, T. Ryu, T. S. Pyo, E. Serabyn, H. Suto, R. Suzuki, Y. H. Takahashi, M. Takami, N. Takato, H. Terada, C. Thalmann, E. L. Turner, M. Watanabe, J. Wisniewski, T. Yamada, H. Takami, T. Usuda, M. Tamura

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5 Scopus citations


We report the direct imaging detection of a low-mass companion to a young, moderately active star V450 And, that was previously identified with the radial velocity (RV) method. The companion was found in high-contrast images obtained with the Subaru Telescope equipped with the HiCIAO camera and AO188 adaptive optics system. From the public ELODIE and SOPHIE archives we extracted available high-resolution spectra and RV measurements, along with RVs from the Lick planet search program. We combined our multi-epoch astrometry with these archival, partially unpublished RVs, and found that the companion is a low-mass star, not a brown dwarf, as previously suggested. We found the best-fitting dynamical masses to be m1 =1.141+0.037 -0.091and m2= 0.279+0.023 -0.020M⊙. We also performed spectral analysis of the SOPHIE spectra with the iSpec code. Hipparcos time-series photometry shows a periodicity of P = 5.743 day, which is also seen in the SOPHIE spectra as an RV modulation of the star A. We interpret it as being caused by spots on the stellar surface, and the star to be rotating with the given period. From the rotation and level of activity, we found that the system is 380 +220 -100Myr old, consistent with an isochrone analysis (220+2120 -90Myr). This work may serve as a test case for future studies of lowmass stars, brown dwarfs, and exoplanets by combination of RV and direct imaging data.

Original languageEnglish (US)
Article number33
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 20 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • binaries: spectroscopic
  • binaries: visual
  • stars: imaging
  • stars: individual (V450 And)
  • stars: low-mass


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