The secondary member, component B, is a magnitude 12.5[3] star at a
projected separation of 2,509±27
AU from the primary.[12] It is a small
red dwarf of spectral class M2.5 V.[5] Periodic variations in the
light curve of this star suggest a rotation period of 43.5 days.[10]
Planetary system
HD 164595 has one known exoplanet, HD 164595 b, which orbits HD 164595 A every 40 days.[19][20] It was detected with the
radial velocity technique with the
SOPHIE echelle spectrograph. Since the inclination of the
orbital plane is unknown, only a lower bound on the mass of the object can be determined. The exoplanet has a minimal mass equivalent of 16
Earths.[19]
In 2016, HD 164595 briefly attracted media attention after it was reported that a possible
SETI signal had been detected from the direction of the star in the previous year. The signal was only heard once and never confirmed by other telescopes, and is thought to have been due to terrestrial interference.
On 15 May 2015, a brief, single radio signal at 11 GHz (2.7 cm wavelength)[22] was observed in the direction of HD 164595 by a team led by N. N. Bursov[23] involving
Claudio Maccone at the
RATAN-600 radio observatory. The signal may have been caused by terrestrial radio-frequency interference or
gravitational lensing from a more distant source.[24][25] It was observed only once (for two seconds), by a single team, at a single telescope, giving it a
Rio Scale[26] score of 1 (insignificant) or 2 (low). Discussions in the media from 29 August 2016 onwards featured speculation that the signal could be caused by an
isotropic beacon from a
Type II civilization.[27]
The senior astronomer of the
SETI Institute,
Seth Shostak, stated that confirmation by another telescope is required.[28] Astronomer
Nicholas Suntzeff of
Texas A&M University stated that the signal is in a military frequency band, and that it could have been a satellite downlink, implying that some such systems may be kept secret and therefore would be unknown to SETI scientists.[22]
^An exact solar twin would be a G2V star with a 5778 K temperature, be 4.6 billion years old, with the correct metallicity and a 0.1%
solar luminosity variation.[18][17]
^
abHarlan, E. A.; Taylor, D. C. (1970). "Erratum: MK classifications for F- and G-type stars. II [Astron. J., Vol. 75, p. 165 - 166 (1970)]". The Astronomical Journal. 75: 507–508.
Bibcode:
1970AJ.....75..507H.
doi:
10.1086/110986.
^
abMontes, D.; et al. (September 2018). "Calibrating the metallicity of M dwarfs in wide physical binaries with F-, G-, and K-primaries - I: High-resolution spectroscopy with HERMES: stellar parameters, abundances, and kinematics". Monthly Notices of the Royal Astronomical Society. 479 (1): 1332–1382.
arXiv:1805.05394.
Bibcode:
2018MNRAS.479.1332M.
doi:
10.1093/mnras/sty1295.
S2CID119260219.
^Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 3. Sky Publishing Corporation and the European Space Agency. p. 1177.
ISBN0-933346-84-0.
^Bursov, N.; et al. (2016). "SETI observations on the RATAN-600 telescope in 2015 and detection of a strong signal in the direction of HD 164595". IAA SETI Permanent Committee. Guadalajara, Mexico.