Nu Ophiuchi — Star in Ophiuchus
About Nu Oph
Description
Nu Ophiuchi is an orange giant of spectral type K0III at magnitude 3.34 in Ophiuchus. Located about 151 light-years from Earth, it has a luminosity of roughly 123 times solar. Nu Oph is notable for hosting two giant planets discovered by radial velocity measurements — both are super-Jupiters with orbital periods of several years.
Observing Tips
Nu Oph lies in the southern reaches of Ophiuchus, not far from the Milky Way. It appears as a warm orange star and is one of several moderately bright stars defining the lower portion of the Serpent Bearer. Best observed from June through September when Ophiuchus is in the evening sky.
History
Nu Ophiuchi has no traditional proper name. Its two giant planets (Nu Oph b and c) were discovered in 2004 and 2010 respectively, making it one of the few giant stars known to host a multi-planet system. The inner planet has a minimum mass of about 22 Jupiter masses, approaching the boundary between planet and brown dwarf.
Fun Facts
Nu Oph's inner 'planet' at 22 Jupiter masses is so massive that some astronomers classify it as a brown dwarf rather than a planet. The system challenges our definitions of what constitutes a planet versus a brown dwarf, a boundary that remains actively debated.
Observe
1Physical Properties
2Position & Identifiers
3How easy to spot?
| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Easy | Easy | Medium+ |
| 50 mm finder 50mm finder | Easy | Easy | Easy |
| 150 mm telescope 150mm scope | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Survey Image
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Explore
7
Size Comparison
8
Compare Stars
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Spectral Classification
10
Hertzsprung-Russell Diagram
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Stellar Lifecycle
12
Blackbody Spectrum
13
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
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Exoplanets
2 known planets
View in 3D
| Planet | Radius | Mass | Period | Distance |
|---|---|---|---|---|
| nu Oph b | 12.00R⊕ | 22.21M♃ | 1.5yr | 151ly |
| nu Oph c | 12.00R⊕ | 24.66M♃ | 8.7yr | 151ly |
Habitable Zone
Size & Mass Comparison
About exoplanets — how we find them and which host stars you can observe
Discover
16
Light Travel Time Machine
17
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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