ScienceNot yet confirmed elsewhere1 publisher2 min readPublished
70 Ophiuchi's second star leaves room for a stable Earth-mass orbit, simulations show
Researchers from over a dozen institutions simulated Earth-mass planets in 70 Ophiuchi and found stable habitable-zone orbits over 10 million years. The same radial-velocity data exclude Jupiter-mass-or-larger planets out to about 5 AU from the primary star.
The Scientist · Science desk
Key figures: Earth-mass planets simulated at 2,000 different distances from the primary star, each tracked over 10 million years; Jupiter-mass-or-larger planets ruled out out to about 5 AU from the primary; radial-velocity precision better than 1 meter per second.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Distances tested from primary | 2,000 distances | 6 | |
| Each simulated planet tracked | 10 million years | 7 | |
| Jupiter-mass planets ruled out to | 5 AU | about, from the primary star | 10 |
| Radial-velocity precision | 1 m/s | better than | 4 |
What happened
- In the simulations, Earth-mass planets were placed at 2,000 different distances from the primary star.
- The radial-velocity data on both stars mixed recent and archival measurements, with eight instruments covering the primary across a century.
- The team reached a radial-velocity precision of better than 1 meter per second.
- 70 Ophiuchi is about 16 light-years away, four times farther than the Proxima Centauri system.
Why it matters
- constraint A stable orbit settles where a planet could stay. Climate and atmosphere are outside what the simulations report, and the zone tested is the primary star's.
- decision In our view, the worry that a companion star rules out habitable-zone orbits is not a sound reason to skip this pair, because the simulations did not support it.
- contradiction Earlier measurements left a Jupiter-sized planet as an explanation for a wobble in the system. The new data exclude Jupiter-mass planets across the range they cover.
ScienceAlert's write-up says the research suggests potentially habitable planets can exist in binary systems "for a very long time" [14]. The run is narrower than that phrase. Each simulated planet was tracked for 10 million years [7], and the team's calculations put the two stars at possibly around 3 billion years old [1]. That makes the window about 0.3 percent of the system's age [15]. K dwarfs can live far longer than the Sun, with lifespans of up to 70 billion years [13], but a star's lifespan does not set how long an orbit holds. We would call the result a 10-million-year stability test and treat anything longer as extrapolation.
The authors' own wording is more careful than the framing. "You might imagine that second star coming through like a wrecking ball and making it impossible for an Earth-sized planet to survive in the habitable zone. But these simulations show that isn't necessarily the case," said Stephen Kane, a University of California, Riverside astrophysicist and co-author [9]. Skylar D'Angiolillo, a UCR planetary scientist and co-author, said: "What we found is that stable orbits are possible in the habitable zone of the primary star." [8] Both statements are about what is possible.
The radial-velocity work addresses a separate matter, what is actually in the system. The team injected fake planet signals into the data to see what it could detect [5]. The reported outcome is the giant-planet exclusion [10]. The source does not give a detection limit for Earth-mass planets. An Earth-sized planet in the habitable zone is therefore dynamically allowed, and the data as reported neither show one nor rule one out.
What to watch
- Orbital integrations that run far past 10 million years, which would test the 'very long time' framing directly.
- A published detection limit for Earth-mass planets from the injected-signal tests.
- Whether the same stability analysis is run for the secondary star's habitable zone.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence55
- Adoption
- Insufficient
- Hype gap+25
- Incentives
- Insufficient
- Confidence55
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The two stars of 70 Oph AB are K dwarfs about 88 percent and 73 percent the mass of the Sun and possibly around 3 billion years old, according to the team's calculations.
- [2]
70 Oph AB is only about 16 light-years away, or four times farther than the Proxima Centauri system.
- [3]
The team incorporated recent and archival radial velocity measurements of both stars, including data from eight instruments for the primary star, across a century of observation.
- [4]
The researchers achieved a radial velocity precision of better than 1 meter per second.
- [5]
The researchers injected fake planet signals into their radial velocity data to see what they could detect.
- [6]
The team simulated Earth-mass planets at 2,000 different distances from the primary star.
- [7]
Each simulated Earth-mass planet was tracked over 10 million years.
- [8]
"What we found is that stable orbits are possible in the habitable zone of the primary star."
ReportedSupportedSource: Skylar D'Angiolillo, Earth and planetary sciences researcher at UC Riverside and study co-authorView cited source - [9]
"You might imagine that second star coming through like a wrecking ball and making it impossible for an Earth-sized planet to survive in the habitable zone. But these simulations show that isn't necessarily the case."
ReportedSupportedSource: Stephen Kane, astrophysicist at UC Riverside and study co-authorView cited source - [10]
The researchers ruled out Jupiter-mass-or-larger giant exoplanets around the two stars, out to about five astronomical units from the primary star.
- [11]
In 1855 British astronomer William Jacob claimed 70 Oph AB had a planet, making it the first host of an exoplanet candidate, University of Michigan researchers point out.
ReportedSupportedSource: University of Michigan researchers, as cited by ScienceAlertView cited source - [12]
Jacob's claim did not survive scrutiny, but more recent measurements showed a wobble that could still have been explained by a Jupiter-sized planet.
- [13]
K dwarfs are calmer and less active than red dwarfs and potentially seven times longer-lived than the Sun, with lifespans of up to 70 billion years.
- [14]
ScienceAlert wrote that new research suggests potentially habitable planets can exist in binary star systems, and for a very long time.
- [15]
The 10-million-year simulation window is about 0.3 percent of the estimated 3-billion-year age of the system.
Sources
1 independent publisher whose own reporting we read for this story.
- sciencealert.comAn Earth-Sized Planet Could Survive With 2 Suns Just 16 Light-Years Away
1 article · October 11, 2026
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Topics
- Habitable zoneFollow
- Radial velocity methodFollow
- Binary star systemsFollow
- ExoplanetsFollow
Entities
- 70 OphiuchiFollow
- Stephen KaneFollow
- Skylar D'AngiolilloFollow
- Yiting LiFollow
- William JacobFollow
- The Astrophysical JournalFollow
- Habitable Worlds ObservatoryFollow