# HD 181433

HD 181433
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pavo
Right ascension 19h 25m 09.5663s[1]
Declination −66° 28′ 07.671″[1]
Apparent magnitude (V) 8.38[1]
Characteristics
Spectral type K5V[2]
B−V color index 1.04[1]
Astrometry
Proper motion (μ) RA: –230.60[3] mas/yr
Dec.: 235.37[3] mas/yr
Parallax (π) 37.37 ± 1.13[3] mas
Distance 87 ± 3 ly
(26.8 ± 0.8 pc)
Absolute magnitude (MV) 6.24[note 1]
Details
Mass 0.86 ± 0.06[4] M
Surface gravity (log g) 4.57 ± 0.04[4] cgs
Temperature 4902 ± 41[4] K
Metallicity [Fe/H] 0.65[4] dex
Age 6.7 ± 1.8[4] Gyr
Other designations
Database references
Exoplanet Archive data
Extrasolar Planets
Encyclopaedia
data

HD 181433 is a star located approximately 87 light-years away[3][note 2] in the constellation of Pavo (the Peacock). According to SIMBAD, it has a stellar classification of K3III-IV,[1] which puts it on the borderline between being a red giant and a subgiant. This is inconsistent with the fact that its luminosity is only 0.308 times that of the Sun.[5] Its entry in the Hipparcos catalogue lists a spectral type of K5V,[2] classifying it as a dwarf star. As of 2008, three extrasolar planets are thought to be orbiting the star.[6] There is currently little information on these planets. The name of this star comes from its identifier in the Henry Draper catalogue.

## Planetary system

Orbiting the star are three planets, the discovery was announced in 2008[7] and the discovery paper was published in 2009.[5] The inner planet has a mass at least 7.5 times that of Earth, and is termed a super-Earth (this classification is based solely on the mass of the planet and should not be taken to imply that the planet could support Earthlike conditions). The middle planet and the outer planet are gas giants. The orbital periods for three planets are 9.3743 days for a 7.56 ME planet, 962 days for a 0.64 MJ planet, and 2172 days for a 0.54 MJ planet.[5] This solution is unstable, more data are required to constrain the orbital position of planet d.[8]

The HD 181433 planetary system[5]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
b ≥0.0238 MJ 0.080 9.3743 ± 0.0019 0.396 ± 0.062
c ≥0.64 MJ 1.76 962 ± 15 0.28 ± 0.02
d ≥0.54 MJ 3.00 2172 ± 158 0.48 ± 0.05

## Notes

1. ^ Calculated from apparent magnitude and parallax (assuming negligible absorption due to interstellar dust): $\textstyle M_{\mathrm{V}} = m_{\mathrm{V}} - 5\log_{10} \left(\frac{100}{\mathrm{parallax\ in\ milliarcseconds}}\right)$
2. ^ Calculated from parallax: $\textstyle \mathrm{Distance\ in\ parsecs}=\frac{1000}{\mathrm{parallax\ in\ milliarcseconds}}$

## References

1. "NLTT 47732 -- High proper-motion star". SIMBAD. Retrieved 2008-10-02.
2. ^ a b ESA (1997). "HIP 95152". The Hipparcos and Tycho Catalogues: The Hipparcos Main Catalogue. Retrieved 2008-10-02.
3. ^ a b c d van Leeuwen, F. (2007). "HIP 95152". Hipparcos, the New Reduction: The Astrometric Catalogue. Retrieved 2008-10-02.
4. Trevisan, M. et al. (November 2011), "Analysis of old very metal rich stars in the solar neighbourhood", Astronomy & Astrophysics 535: A42, arXiv:1109.6304, Bibcode:2011A&A...535A..42T, doi:10.1051/0004-6361/201016056. See table 13.
5. ^ a b c d Bouchy, F. et al. (2009). "The HARPS search for southern extra-solar planets. XVII. Super-Earth and Neptune-mass planets in multiple planet systems HD 47186 and HD 181433". Astronomy and Astrophysics 496 (2): 527–531. arXiv:0812.1608. Bibcode:2009A&A...496..527B. doi:10.1051/0004-6361:200810669.
6. ^ "A Trio of Super-Earths" (Press release). ESO. 2008-06-16. Retrieved 2008-10-02.
7. ^ "Astronomers find batch of "Super Earths"". BT Yahoo.com. Archived from the original on 2008-06-17. Retrieved 2008-06-16.
8. ^ Campanella, G. (2011). "Treating dynamical stability as an observable: a 5:2 MMR configuration for the extrasolar system HD 181433". MNRAS 418: 1028–1038. arXiv:1108.0360. Bibcode:2011MNRAS.418.1028C. doi:10.1111/j.1365-2966.2011.19553.x.