Key parameters at a glance
- A radius of 4.43 Earth radii
- A mass of 17.98 Earth masses
- Surface gravity around 0.92 g
- An orbital period of 49.770 days
- Semi-major axis 0.2500 AU
- Distance from Earth 71.59 light-years
- Earth Similarity Index 0.513
- Travel time at Voyager 1 speed 1,262,488 years
Context from the literature
HD 90156 is a star with an orbiting exoplanet in the constellation Hydra. Based on parallax measurements, it is located at a distance of 71.6 light-years from the Sun. The system is drifting further away with a heliocentric radial velocity of 27 km/s. The apparent visual magnitude of this star is 6.92, which is places it near the lower limit of visibility to the naked eye. A survey in 2015 ruled out the existence of any stellar companions at projected distances above 5 AU.
Excerpted from Wikipedia · full article
HD 90156 b Planet Profile
Physical Specs
Classification
Planet Type
Neptune-like
Discovery
Size rank in cohort
Rank by radius
#468of 574
top 81.4%
This planet
4.43R⊕
Neptune-like median
6.39R⊕
Nearest-size peers
| Metric | Earth | HD 90156 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 4.43 | 11.21 |
| Mass (M⊕) | 1.00 | 17.98 | 317.83 |
| Density (g/cm³) | 5.51 | 1.14 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.92 | 2.53 |
| Insolation (S⊕) | 1.00 | — | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Minimum mass (M sin i) | 17.980 M⊕ | Lower bound from radial-velocity fitting. |
Star Catalogue Identifiers
HD
HD 90156
HIP
HIP 50921
TIC
TIC 193032655
Gaia DR2
Gaia DR2 5461620846141553024
Gaia DR3
Gaia DR3 5461620846141553024
System
HD 90156
Percentile among Neptune-like cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 49.77 Earth days (13.6% of a terrestrial year) on a highly eccentric trajectory at a mean orbital distance of 0.2500 AU.
Extended Orbital Architecture
RV semi-amplitude (K)
3.690 m/s
Transit mid-time (BJD)
2,455,169.3000
Long. of periastron (ω)
113.00°
Angular separation (arcsec)
11.40000
Eq. Temperature
—
Insolation (S⊕)
—
Earth = 1.00
Earth Similarity (ESI)
0.513
0 = alien, 1 = Earth-identical
Discovery Paper
Primary reference
Mordasini et al. 2011Instrument
HARPS Spectrograph
Publication
2011-02
Observation locale
Ground
Discovery cohort
Planets confirmed in 2009 at La Silla Observatory (12 shown).
Host System: HD 90156
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,599 K — cooler than the Sun (5,778 K)
Estimated Age
4.40 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.920 R☉
Stellar Mass
0.840 M☉
Metallicity [Fe/H]
-0.24
Extended Stellar Properties
Surface gravity (log g)
4.480 dex
Stellar density
1.956 g/cm³
Systemic radial velocity
26.85 km/s
Rotational v·sin i
0.00 km/s
Activity index (log R'HK)
-4.950
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
45.530 mas
Total Proper Motion
106.509 mas/yr
PM Right Ascension
-39.09 mas/yr
PM Declination
99.08 mas/yr
Galactic Cartesian (pc)
x = -0.794 · y = 0.354 · z = -0.495
Equatorial (J2000)
RA 155.98011° · Dec -29.64510°
Galactic ℓ, b
268.372° · 23.152°
Ecliptic λ, β
170.849° · -36.479°
HTM-20 index
-1442401804
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Kepler-1730 b
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