Key parameters at a glance
- A radius of 3.43 Earth radii
- A mass of 7.00 Earth masses
- Surface gravity around 0.60 g
- An orbital period of 52.564 days
- Semi-major axis 0.2690 AU
- Equilibrium temperature 470 K (197 °C)
- Distance from Earth 220.31 light-years
- Earth Similarity Index 0.429
- Travel time at Voyager 1 speed 3,885,188 years
1 sibling around HIP 9618
HIP 9618 c shares its host star with 1 other confirmed planet. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| HIP 9618 b | Sub-Neptune | 3.83 | 8.30 | 20.773 | 641 | 2023 |
| HIP 9618 c this | Sub-Neptune | 3.43 | 7.00 | 52.564 | 470 | 2023 |
HIP 9618 c Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#209of 1978
top 10.5%
This planet
3.43R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | HIP 9618 c | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 3.43 | 11.21 |
| Mass (M⊕) | 1.00 | 7.00 | 317.83 |
| Density (g/cm³) | 5.51 | 1.00 | 1.33 |
| Surface Gravity (g) | 1.00 | 0.60 | 2.53 |
| Insolation (S⊕) | 1.00 | 11.70 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 7.000 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
HD
HD 12572
HIP
HIP 9618
TIC
TIC 306263608
Gaia DR2
Gaia DR2 94468978202180352
Gaia DR3
Gaia DR3 94468978202180352
System
HIP 9618
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 52.56 Earth days (14.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2690 AU.
Transit Fingerprint
Depth
0.119 %
Duration
6.572 h
Impact parameter b
0.291
Rp / R★
0.032768
Transit midpoint (BJD)
2,458,779.1904
Photometric dip
Transit produces a flux drop of 1,193 ppm lasting ≈ 6.57 h.
Extended Orbital Architecture
Planet / star radius ratio
0.032768
Semi-major axis / stellar radius
61.000
Impact parameter (b)
0.291
RV semi-amplitude (K)
1.390 m/s
Transit mid-time (BJD)
2,458,779.1904
Long. of periastron (ω)
90.00°
Angular separation (arcsec)
3.98000
Eq. Temperature
470K
(197 °C)
Insolation (S⊕)
11.70
Earth = 1.00
Earth Similarity (ESI)
0.429
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Osborn et al. 2023Instrument
TESS CCD Array
Publication
2023-08
Observation locale
Space
Discovery cohort
Planets confirmed in 2023 at Transiting Exoplanet Survey Satellite (TESS) (12 shown).
Host System: HIP 9618
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,649 K — cooler than the Sun (5,778 K)
Estimated Age
5.60 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.959 R☉
Stellar Mass
0.942 M☉
Metallicity [Fe/H]
-0.02
Extended Stellar Properties
Surface gravity (log g)
4.445 dex
Stellar density
1.490 g/cm³
Activity index (log R'HK)
-4.990
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 11 bands
Astrometric Data
Parallax
14.776 mas
Total Proper Motion
191.883 mas/yr
PM Right Ascension
158.82 mas/yr
PM Declination
107.68 mas/yr
Galactic Cartesian (pc)
x = 0.800 · y = 0.479 · z = 0.363
Equatorial (J2000)
RA 30.90501° · Dec 21.28133°
Galactic ℓ, b
144.587° · -38.536°
Ecliptic λ, β
36.118° · 8.200°
HTM-20 index
1752874521
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TOI-1723 b
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TOI-132 b
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KOI-142 b
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Kepler-223 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 3.44 R⊕ · 6,065.6 ly