Smugglers Log:
Stars and Related Matters

by Johannes M. Bowers


Someone recently asked me, how close can a ship (safely) approach a star? How much do shields protect, and how much of a factor is the star's type? What effect does this have on sensors?

There is precedent in STAR WARS for getting extremely close to a star - in fact, concealing an entire Rebel fleet in one. It required a set of essentially Death Star scale shield generators linked to form a shielded "cage" that would then drop into a star's outer layers (one of the cooler ones) and orbit at a very high speed. With the benefit of the shield generators, the fleet was protected; however, there was still some danger if you were too close to the shield walls. R2 and C3PO had to make a quick EVA for some repairs and suffered some damage while out there from exposure/radiation.

As for sensors, that was exactly the premise used to conceal the fleet in the above (Marvel) storyline. Sensors could not penetrate into the solar coronal layers, so the fleet could stay hidden. Even under optimal conditions, the "submerged" fleet could not remain there indefinitely, and of course, being STAR WARS, problems developed (thus the necessity for the EVA). But certainly, unless an Imperial Stellar Cartography or Science ship were analyzing the star closely, there ought to be nothing short of the Force that could detect someone hiding in a star. Surviving that process is of course another matter entirely.

Specialized equipment is absolutely required for a long term immersion. Shields (preferably Capital scale or above) are mandatory for even the most high speed pass, as well as piloting rolls to avoid hazards like flares and navigate the layers/currents of the star safely.

HOW HOT IS HOT?
Our Sun's core can reach 10 to 22.5 million°F. The surface temperature is approximately 9,900°F (5,500°C). The outer atmosphere or corona of the Sun (which we can see during a solar eclipse) gets extremely hot again, up to 1.5 to 2 million degrees, but is extremely thin. At the center of big sunspot clusters the temperature can be as low as 7300 °F (4000 °C). The temperature of the Sun is determined by measuring how much energy (both heat and light) it emits.

To survive, you should target a sunspot to pass through the corona safely (or have really good shields and be quick) that allows you to enter the "safe zone" (a relative term) just above the surface and below the corona.

(much astronomy geek stuff follows after the STATS)

Type Temperature Damage Scale Difficulty
O over 25,000 °C 30D DS/DS Heroic + 50
B 11,000 - 25,000 °C 20D DS/DS Heroic + 30
A 7,500 - 11,000 °C 10D DS/Cap Heroic + 20
F 6,000 - 7,500 °C 8D DS/Cap Heroic
G 5,000 - 6,000 °C 6D Cap/Cap Very Difficult
K 3,500 - 5,000 °C 5D Cap/SF Difficult
M under 3,500 °C 5D Cap/SF Moderate

The first scale is for the corona, the second for the "safe zone." Roll once per pass, or per hour, or whatever feels right to you as the GM.

If the player rolls both piloting and shields successfully, they can remain in the layer without taking damage. Failing the piloting roll means they take damage as appropriate to the layer against their shields. Failing the shields roll but making the piloting roll results in damage reduced by one scale, but no shields. Failing both rolls... toasty...

I definitely would use the Rules of Engagement rules for Die Pool or Skill roll overage to adjust the Shield+Hull Rolls to resist damage, to reflect "tuning" the shields to the star type. I also would allow for the MacGyver types to attempt to boost the shields by redirecting power from other systems (like weapons, or life support if desperate) with appropriate repair rolls.


Other Hazards: Solar Flares, Prominences, the Solar Wind, and Coronal Mass Ejections

SOLAR FLARES
A solar flare is a magnetic storm which appears to be a very bright spot and a gaseous surface eruption. Solar flares release huge amounts of high-energy particles and gases and are tremendously hot (from 3.6 million to 24 million °F). They are ejected thousands of miles from the surface of the star.

Solar Flares hit your vessel at the star's upper Damage Scale or double the dice of damage.

SOLAR PROMINENCE
A solar prominence (also known as a filament) is an arc of gas that erupts from the surface of the star. Prominences can loop hundreds of thousands of miles into space. Prominences are held above the star's surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of stellar material into space.

Striking a Solar Prominence subjects you to a star's upper scale damage or double the number of D. But at least you can usually see it coming.

SOLAR WIND
The solar wind is a continuous stream of ions (electrically charged particles) that are given off by magnetic anomalies on the Sun. The solar wind is emitted where the star's magnetic field loops out into space instead of remaining within its volume. These magnetic anomalies in the corona are called coronal holes. In X-ray photographs of the Sun, coronal holes are black areas. Coronal holes can last for months or years.

It takes the solar wind about 4.5 days to reach Earth, at a range of 93 million miles; it has a velocity of about 250 miles/sec (400 km/sec). Adjust as appropriate for other planets. Since the particles are emitted from the star as it rotates, the solar wind blows in a pinwheel pattern through the system. The solar wind affects the entire system, including pushing comets' tails away from the Sun, causing auroras on Earth (and some other planets that have their own magnetic fields), the disruption of electronic communications on Earth, nudging ships and satellites around, etc.

Entering a Coronal Hole region subjects you to an ION attack of the star's damage D at the scale of the level you are in (Coronal or Sub-Coronal).

CORONAL MASS EJECTION
Coronal mass ejections (CMEs) are huge, balloon-shaped plasma bursts that come from the Sun. As these bursts of solar wind rise above the corona, they move along the star's magnetic field lines and increase in temperature up to tens of millions of degrees These bursts release up to 220 billion pounds (100 billion kg) of plasma. CMEs can disrupt the electronics of satellites and unshielded ships orbiting nearby worlds. CMEs usually happen independently, but are sometimes associated with solar flares.

CMEs subject any vessel in their path to double damage at the next scale up. (Yes, these are really bad news. But just the thing to have happen to whoever foolishly followed your PCs' ship into the star.)


And now, as promised, the geek stuff...

Stars are classified by their spectra (the elements that they absorb) and their temperature. There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M ("Oh Be A Fine Girl Kiss Me"). They are further divided by numbers, counting down from 0 to 9. Our Sun is a G2 star.

O and B stars are uncommon but very bright; one of these will be a landmark for an entire region. M "red dwarf" stars are the most common, but very dim. Most inhabited worlds will circle F, G, or K type stars. (Some of the brighter types are too hot and burn out too fast - a mere billion years or so - to even form planets, let alone life.)

Type Mass Radius Luminosity Notes Examples
O 60 15 1,400,000 Singly ionized helium lines (H I) either in emission or absorption. Strong UV continuum. Alnitak, Mintaka
B 18 7 20,000 Neutral helium lines (H II) in absorption. Rigel, Spica
A 3.2 2.5 80 Hydrogen (H) lines strongest for A0 stars, decreasing toward A9 Sirius, Vega
F 1.7 1.3 6 Ca II absorbtion. Metallic lines become noticeable. Canopus, Procyon
G 1.1 1.1 1.2 Absorption lines of neutral metallic atoms and ions (e.g., once-ionized calcium) Capella, Sol (the Sun)
K 0.8 0.9 0.4 Metallic lines, some blue continuum. Aldebaran, Arcturus
M 0.3 0.4 0.04 Some molecular bands of titanium oxide. Antares, Betelgeuse

Note that this table is calibrated in terms of solar masses, radii, and luminosity. (Luminosity is the total amount of energy that a star radiates in all wavelengths of electromagnetic radiation, not just the visible.) So an average M-type star masses only a third of what our Sun does, is a little under half as big, and puts out only 4 percent as much heat and light. The red giants that we've seen and named from Earth are much bigger, but not much hotter.

Also, the temperatures given in the first table are actually in the Kelvin scale (°K), which uses the same degrees as Celsius but starts 300 degrees colder, and is more useful for the very cold temperatures of space. When talking of temperatures in the thousands of degrees, however, it doesn't make much difference.


FULONGAMER
aka
Johannes M. Bowers



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