Wolf 1061 (also known as HIP 80824 and V2306 Ophiuchi) is an M class red dwarf star located about 13.8 light years away in the constellation Ophiuchus. It is the 36th closest known star system to the Sun and has a relatively high proper motion of 1.2 seconds of arc per year. Like many red dwarfs, it most likely has a long rotation period of more than 100 days, although it is difficult to measure accurately. Wolf 1061 does not have any unusual spectroscopic features. The star was first cataloged in 1919 by German astronomer Max Wolf when he published a list of dim stars that had high proper motions. Wolf 1061's name originates from this list. The star has a stellar rotation period of 89.3±1.8~ days. A seven years study found no evidence of photometric transits and confirms the radial velocity signals are not due to stellar activity. The habitable zone estimate for the system lies between approximately 0.1 and 0.2 AU from the star.
Epoch J2000 Equinox J2000
|Right ascension||16h 30m 18.0584s|
|Declination||–12° 39′ 45.325″|
|Apparent magnitude (V)||10.07 (10.05 - 10.10)|
|U−B color index||+1.20|
|B−V color index||+1.57|
|Variable type||BY Draconis|
|Radial velocity (Rv)||–21.22 km/s|
|Proper motion (μ)||RA: –94.212 mas/yr
Dec.: 1,183.679 mas/yr
|Parallax (π)||232.29 ± 0.49 mas|
|Distance||14.04 ± 0.03 ly
(4.305 ± 0.009 pc)
|Absolute magnitude (MV)||11.87|
|Radius||0.307 (± 0.027) R☉|
|Luminosity (bolometric)||0.0102 L☉|
|Luminosity (visual, LV)||0.0015 L☉|
|Temperature||3342 ± 49 K|
|Metallicity [Fe/H]||–0.09 ± 0.09 dex|
|Rotation||94 ± 1 days|
In December 2015, a team of astronomers from the University of New South Wales announced the discovery of three planets orbiting Wolf 1061. The planets were detected by analyzing 10 years of observations of the Wolf 1061 system by the HARPS spectrograph at La Silla Observatory in Chile. The team used archive radial velocity measurements of the star's spectrum in the HARPS data and, along with 8 years of photometry from the All Sky Automated Survey, discovered two definite planets with orbital periods of around 4.9 and 17.9 days and a very likely third with a period of 67.3 days.
All three planets have masses low enough that they are likely to be rocky planets similar to the inner planets of the Solar System although their actual sizes and densities are currently unknown. However, this information could be determined if the planets happen to transit in front of Wolf 1061 when viewed from Earth. Because all three planets orbit close to the star and have short orbital periods, there is a chance that this will occur. The University of New South Wales team estimated the chances of a transit at around 14% for planet b, 6% for planet c, and 3% for planet d.
One of the planets, Wolf 1061 c, is a super-Earth located near the inner edge of the star's habitable zone, which conservatively extends from 0.11 to 0.21 AU, or at most from 0.09 to 0.23 AU. It is one of the closest known potentially habitable planets to Earth after Proxima b, Ross 128 b, and Luyten b. The next planet out, Wolf 1061 d, could be marginally habitable depending on its atmosphere's composition as it orbits just beyond the habitable zone.
In March 2017, another team of astronomers re-analyzed the system using the HARPS spectrograph. They found planets b and c to be quite similar to their originally reported parameters, but found that planet d was more massive and in a larger, more eccentric orbit. The team was also able to find updated parameters for the host star. Their results showed that Wolf 1061 c is slightly smaller, yet closer to the inner edge of the habitable zone.
(in order from star)
|b||≥1.91 ± 0.25 M⊕||0.0375 ± 0.0012||4.8869 ± 0.0005||0.15 +0.13
|—||1.2 (estimated) R⊕|
|0.0890 ± 0.003||17.8719 ± 0.0059||0.11 +0.10
|—||1.45 (estimated) R⊕|
|0.470 ± 0.016||217.21 +0.55
|—||2.2 (estimated) R⊕|
- "Astronomers discover closest potentially habitable planet: Wolf 1061c". ScienceAlert.com. 17 December 2015. Retrieved 17 December 2015.
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- Sarah Griffiths (17 December 2015). "'Super-Earth' is spotted just 14 light years away: Wolf 1061c is the closest 'habitable' planet outside our solar system ever found". Daily Mail.
- Stuart Gary (17 December 2015). "Potentially habitable super-Earth discovered orbiting star 14 light years from Earth". ABC News (Australia).