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
Lifeforms Prokaryotic microbes

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

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.

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

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.

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.

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

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

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.

Most military ships travel to and from Core IV.