Temperature
5588 K
5566.5 to 5695
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Stellar HostProfile
HAT-P-21
G3 • 277.3 pc
Records
7
literature rows
Planets
1
system count
References
8
distinct source labels
TIC: TIC 17993892
Approximate color
from effective temperature
Canonical Summary
Adopted host values from one source row
Values come from the row with the most populated summary measurements. Missing values stay missing. Ranges and counts describe all source rows.
Stellar source: Bakos et al. 2010 • System source: TICv8
Mass
0.95 Msun
0.95 to 1.24
Radius
1.10 Rsun
1.10 to 1.28
Age
10.20 Gyr
7.80 to 10.20
Luminosity
0.03 log(Lsun)
0.03 to 0.18
Distance
277.3 pc
single adopted value
Spectral Type
G3
Consistent across records
Planets
1
Stable across source rows
Scale Comparison
Radius against the Sun
Current adopted radius: 1.10 R☉ (circles scaled linearly by radius)
Sun
1.0 R☉ baseline
HAT-P-21
1.10 R☉
System Layout
Known planets
1 planets linked to this host
HAT-P-21 b
Transit
◌
Discovery
2010
Period
4.12 days
Radius
12.44 R⊕
Mass
1547.8 M⊕
Eq. Temp
—
HAT-P-21 and Its Jupiter-Like Planet
HAT-P-21 is a G3 star located 904 light-years away. Its mass is 0.947 solar masses, its radius is 1.11 solar radii, and its temperature is 5590 K. The star's reported mass estimate is smaller than the Sun's, while its reported radius estimate is larger than the Sun's and its reported temperature is cooler than the Sun's. Its age is 10.2 billion years.
One planet orbits this host: HAT-P-21 b, a Jupiter-like world discovered by transit in 2010. It has a mass of 1550 Earth masses, a radius of 12.4 Earth radii, and an orbital period of 4.12 days. Its reported radius estimate is larger than Earth's, as is its reported mass estimate, which is roughly 4.87 times Jupiter's mass. Its mean density is 4.43 g/cm³, 0.804 times Earth's.
Provenance
Underlying measurements and references
Evidence Summary
Rows
7
Stellar refs
7
System refs
1
Distancestable
Parallaxstable
Temperaturedisputed
Massdisputed
Radiusdisputed
Agedisputed
Luminositydisputed
Surface Gravitydisputed
Metallicitydisputed
Spectral Typestable
| ST TEFF | ST MASS | ST RAD | ST AGE | ST LUM | ST SPECTYPE | SY DIST | Stellar Ref | System Ref |
|---|---|---|---|---|---|---|---|---|
| 5695 | 1.00 | 1.25 | 7.80 | 0.18 | — | 277.3 | Mancini et al. 2022 | TICv8 |
| 5634 | — | 1.26 | — | — | — | 277.3 | ExoFOP | TICv8 |
| 5566.5 | — | 1.28 | — | 0.15 | — | 277.3 | Gaia DR2 | TICv8 |
| 5588 | 0.95 | 1.10 | 10.20 | — | — | 277.3 | Bonomo et al. 2017 | TICv8 |
| 5634 | 1 | 1.26 | — | 0.16 | — | 277.3 | TICv8 | TICv8 |
| 5588 | 0.95 | 1.10 | 10.20 | 0.03 | G3 | 277.3 | Bakos et al. 2010 | TICv8 |
| 5588 | 1.24 | 1.21 | — | — | — | 277.3 | Stassun et al. 2017 | TICv8 |