The Core system is a fairly unusual star system as it is a red dwarf with two planets in the habitable zone.

Type M8 V Red Dwarf
Radius 2.67 x 105 km (0.38 x sol)
Mass 5.27 x 1029 kg (0.26 x sol)
Temperature 2200 K
Luminosity 1.48 x 1025 W (0.04 x sol)

Type Terrestrial World
Orbital Radius 2.36 x 107 km (0.16 AU)
Period 1.07 x 103 hours (0.12 earth years)
Type Standard iron/silicate
Radius 6265.74 km (0.98 x earth)
Surface Area 4.93 x 108 km2
Land Area 2.91 x 108 km2 (1.95 x earth)
Mass 5.63 x 1024 kg (0.94 x earth)
Density 5.47 g/cm3 (0.99 x earth)
Composition 30.8% oxygen, 29.9% iron, 17.8% silicon, 17.0% aluminum, 4.6% other metals, trace other elements
Gravimetry
Gravity 9.53 m/s2 (0.97 x earth)
Escape Velocity 10.93 km/s
Rotation
Period 16.66 hours
Axis Tilt 24.05 °
Hydrosphere
Water 42 %
Ice 4 %
Atmosphere
Type Dense breathable
Pressure 140.51 kPa (1.39 x earth)
Composition 46.6% argon, 32.0% nitrogen, 21.4% oxygen, trace other gases
Climate
Type Standard
Min Temp 233 K (-39 °C)
Avg Temp 297 K (24 °C)
Max Temp 341 K (68 °C)
Biosphere
Chemistry Carbon

This is the center of the empire and all the important imperial functions are there.

About 140 billion people live here, making it the most populated planet in the empire.

Type Terrestrial World
Orbital Radius 3.61 x 107 km (0.24 AU)
Period 2.01 x 103 hours (0.23 earth years)
Radius 3559.80 km (0.56 x earth)
Surface Area 1.59 x 108 km2
Land Area 1.31 x 108 km2 (0.88 x earth)
Mass 1.03 x 1024 kg (0.17 x earth)
Density 5.45 g/cm3 (0.99 x earth)
Composition 51.0% iron, 25.2% oxygen, 23.7% silicon, trace other elements
Gravity 5.40 m/s2 (0.55 x earth)
Escape Velocity 6.20 km/s
Rotation
Period 36.74 hours
Axis Tilt 7.79 °
Hydrosphere
Water 19 %
Ice 32 %
Atmosphere
Type Thin toxic
Pressure 69.57 kPa (0.69 x earth)
Composition 59.8% sulfur dioxide, 20.1% nitrogen, 16.3% oxygen, 2.5% argon, 1.3% carbon dioxide, trace other gases
Climate
Type Cold
Min Temp 255 K (-17 °C)
Avg Temp 281 K (8 °C)
Max Temp 371 K (98 °C)
Biosphere
Chemistry Carbon
Lifeforms Prokaryotic microbes
Special
Features Planetary rings

This is the main industrial hub of core.

The atmosphere is breathable with a special respirator filter mask: TL 9 Respirator filter: eyes, face DR 10 $300 1.35kg. It runs on a B cell for one day(TL9), three days (TL10), 10 days, (TL11). It takes three seconds to put on and one to take off.

About 42 billion people live and work here, most in the major industries or the service industries for the workers.

Type Rock Planet
Orbital Radius 4.63 x 107 km (0.31 AU)
Period 2.93 x 103 hours (0.33 earth years)
Gravity 11.18 m/s2 (1.14 x earth)
Special Electromagnetic storms

The truly magnificent electromagnetic storms that can light up the whole sky make this planet a fairly popular resort location. About 100 million people live here to cater to the tourist trade(and there can be up to 300 million tourists at any given time)

Type Rock Planet
Orbital Radius 7.47 x 107 km (0.50 AU)
Period 5.99 x 103 hours (0.69 earth years)
Gravity 10.97 m/s2 (1.12 x earth)
Special Trace atmosphere

This is the military hub of the empire, The navy and army main bases are located here, along with many other bases.

About 5 billion people live here, mostly belonging to one of these groups: Military, military dependents, naval shipyard workers, services.

Type Rock Planet
Orbital Radius 1.22 x 108 km (0.81 AU)
Period 1.24 x 104 hours (1.42 earth years)
Gravity 8.30 m/s2 (0.85 x earth)

Core V and the many space stations orbiting it are the system main starport.

About 3 billion people live on the planet and the orbiting stations, most involved in the transportation and trade somehow.

Type Ice Planet
Orbital Radius 2.09 x 108 km (1.40 AU)
Period 2.80 x 104 hours (3.21 earth years)
Gravity 11.01 m/s2 (1.13 x earth)
Special Electromagnetic storms
Trace atmosphere

This is a truly hostile place with vulcanism, electromagnetic storms, normal storm, earthquakes ans so on. Hostile environment gear is often tested here and is then said to be “6-proof”

Army special forces and navy rescue often train here for hostile environments too.

Type Ice Planet
Orbital Radius 4.05 x 108 km (2.71 AU)
Period 7.57 x 104 hours (8.66 earth years)
Gravity 14.35 m/s2 (1.47 x earth)
Special Large moon

This planet is seen as a planet of mystery and is the home of many mystical orders. Most such attribute some special meaning to the world.

There are about 10 million people living here, most in the monasteries.

Type Ice Planet
Orbital Radius 7.77 x 108 km (5.19 AU)
Period 2.01 x 105 hours (23.01 earth years)
Gravity 10.55 m/s2 (1.08 x earth)
Special Trace atmosphere

Space travel to/from and within Core system is highly regulated. Most private ships are limited to specific travel lines going to and from Core V. Any cargo and passengers headed to other places in the system will have to go though immigration and customs there and then transit to in system transport.

Specially cleared cargo transports are allowed to and from Core II.

Most military ships travel to and from Core IV.