Star · G5 V
KOI-1257
KOI-1257 is a main-sequence star of spectral type G5 V in the constellation Cygnus, 2,140 light-years from the Sun. It is orbited by 1 confirmed exoplanet(s).
| Constellation | Cygnus |
|---|---|
| Distance | 2,140 light-years (656.0 pc) |
| Apparent magnitude | magnitude 14.82 |
| Absolute magnitude | magnitude 5.74 |
| Spectral type | G5 V |
| Surface temperature | 5,520 K |
| Luminosity | 1.07 L☉ |
| Radius | 1.13 R☉ |
| Mass | 0.99 M☉ |
| Age | 9.3 billion years |
| Metallicity [Fe/H] | 0.27 |
| Right ascension (J2000) | 19h 24m 54.0s |
| Declination (J2000) | +44° 55′ 38″ |
| Space velocity (relative to the Sun) | 51.0 km/s |
In the sky
A telescope is needed to see it: its apparent magnitude is 14.82. Visible from the whole Northern Hemisphere and south to latitude 45° S. North of latitude 45° N it never sets. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out around 115 BC. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 38 million years.
The Sun seen from there
From a planet around KOI-1257, the Sun would look like a star of magnitude 13.91, in the direction where our sky has the constellation Puppis. It would be invisible to the naked eye.
Planets
- KOI-1257 b 86.6-day orbit · 10.5 R⊕
Stellar parameters from the NASA Exoplanet Archive; position and brightness from the HYG / AT-HYG catalogue.