HD 108874

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**HD 108874**
Observation data Epoch 2000
Constellation (pronunciation)	Coma Berenices
Right ascension	12^h 30^m
Declination	+22° 52' 47.383"
Apparent magnitude (V)	8.76
Characteristics
Spectral type	G5 V
U-B color index	?
B-V color index	?
Variable type	?
Astrometry
Proper motion (μ)	RA: -45.05 mas/yr Dec.: -105.39 mas/yr
Parallax (π)	30.71 ± 0.81 mas
Distance	106 ly (30.6 pc)
Absolute magnitude (M_V)	3.72
Details
Mass	1 M_☉
Radius	1.22 R_☉
Luminosity	? L_☉
Temperature	5407 K
Metallicity	[Fe/H]=+0.14
Rotation	?
Age	7.26 Giga- years
Other designations
BD+23°2466,HIP 61028

HD 108874 is a yellow dwarf star (spectral type G5 V) in the constellation of Coma Berenices. It is 223 light years from Earth and has two extrasolar planets that are possibly in a 4:1 orbital resonance.

1 Planets
- 1.1 HD 108874 b
- 1.2 HD 108874 c
2 References

[edit] Planets

[edit] HD 108874 b

**HD 108874 b**
Orbital elements

Semi-major axis a:	1.051 ± 0.02 AU
Eccentricity e:	0.07 ± 0.04
Orbital period P:	395.4 ± 2.5 d
Inclination i:	?°
Angular distance θ:	15.343 mas
Longitude of periastron ω:	248.4 ± 36°
Time of periastron τ:	2,450,131.5 ± 60 JD
Semi-amplitude K:	37.91 ± .95 m/s
Physical characteristics
Mass:	>1.36 ± 0.13 M_J
Radius:	? R_J
Density:	? kg/m³
Gravity:	? g
Temperature:	? K
Discovery
Discovery date:	2003
Discovery site:
Detection method(s):
Discoverer(s):	Butler, Marcy, Vogt, Fischer et al.
Other catalogue

HD 108874 b is a gas giant discovered in 2003 that orbits in the star's habitable zone.

Of all 294 planets found so far (June/08) it has the most Earth-like insolation.

Using the following formulas, derived from Luminosity(watts) = 4pi·R²aT⁴ = 4pi·d²f

the Average, Apastron, and Periastron heat received by this planet can be calculated:

R, Star Radius (km)

a, Stefan-Boltzmann constant (5.67051e-8)

T, Star Effective temperature °K

f, Irradiance, Solar Constant (W/m²)

d, Semi-major axis (meters)

Periastron Flux: $f_p= \frac{( (1.22 \times 6.955 \times 10^8 )^2 ) \times (5.67051 \times 10^{-8}) \times (5407^4 K)} { ( ( 1.051- ( 1.051\times 0.07 ) ) \times 149597876600 m)^2 }$

Average Flux: $f_p= \frac{( (1.22 \times 6.955 \times 10^8 )^2 ) \times (5.67051 \times 10^{-8}) \times (5407^4 K)} { 1.051 \times 149597876600 m)^2 }$

Apastron Flux: $f_p= \frac{( (1.22 \times 6.955 \times 10^8 )^2 ) \times (5.67051 \times 10^{-8}) \times (5407^4 K)} { ( ( 1.051+ ( 1.051\times 0.07 ) ) \times 149597876600 m)^2 }$

Planet Distance	Insolation (W/m²)	% of Earth's.
HD 108874 b Apastron Flux	1234.655541	90.12%
Earth's Aphelion Flux	1325.277174	93.74%
Earth's Average Flux	1369.938576	100.00%
HD 108874 b Average Flux	1413.557129	103.18%
Earth's Perihelion Flux	1416.896227	103.43%
HD 108874 b Periastron Flux	1634.359035	119.30%
Venus' Aphelion Flux	2,585.411	188.72%
Venus' Average Flux	2,620.693	191.30%
Venus' Perihelion Flux	2,656.70	193.93%

Being that HD 108874 b is a gas giant 1.36 (+/-0.13) times the mass of Jupiter, and that it has the most Earth-like Insolation to date (12/2007), it has the best probablity of having habitable moons.

[edit] HD 108874 c

**HD 108874 c**
Orbital elements

Semi-major axis a:	2.68 ± 0.25 AU
Eccentricity e:	0.25 ± 0.07
Orbital period P:	1605.8 ± 88 d
Inclination i:	?°
Angular distance θ:	39.124 mas
Longitude of periastron ω:	17.3 ± 23°
Time of periastron τ:	2,449,584.8 ± 180 JD
Semi-amplitude K:	18.35 ± .86 m/s
Physical characteristics
Mass:	>1.018 ± 0.3 M_J
Radius:	? R_J
Density:	? kg/m³
Gravity:	? g
Temperature:	? K
Discovery
Discovery date:	2005
Discovery site:
Detection method(s):
Discoverer(s):	Vogt, Butler Marcy, Fischer et al.
Other catalogue