Fireball class star system

StilLearning

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Hey everyone, I'm editing the 3rd draft of a non-fic designed to help authors and other worldbuilders build solar systems with realistic astrophysics for the worlds they make (not the worlds themselves as there are already a lot of worldbuilding systems that will let you do that): That can be a simple as just selecting a sun colour and getting basic details of what the corresponding sky would be like (e.g. sky colour, how big and bright any other planets are, how frequent aurora would be etc.), or can be quite detailed - there's a section detailing other planets that can be added for example. It's also possible to combine single solar systems into multi-star systems with multiple suns visible in the sky, each with an independent collection of planets (if required), complete with descriptions of how those suns would change positions over time, and what the day and night cycles would be like.

The excerpt below is the quick-look-up sheet for 'fireball class' star systems. These are the largest type of single-sun system dealt with, with the heaviest and hottest central sun (a blue-white A-type star). I'm wondering if, since you guys are my target audience, I could get your feedback on how accessible the information is, if there's anything obvious a world builder would want that I'm forgetting, anything superfluous, etc. etc.? If anyone can see any obvious mistakes in the science then please feel free to point that out too, although it's more general stuff I'm focused on at the moment, as I'm planning to do a review and edit aimed specifically at the scientific details at a later point. The book has lots of additional notes, and a glossary, which will get linked and referenced to throughout - I've not set those up yet. I am going to include an explanation of the units used below.
Many thanks




Fireball system:​

Large star, giving white-blue light. Planets are spread much wider than the Sun’s, showing dim points at night, interplanetary travel is much slower. HZ is broader, further out.


Basic stats:
Age range: Habitable zone*:Dimensions: Radiation levels:Opportunities:Hazards:Visuals in brief:
Up to around a billion years old.Inner edge:
2.7 AU

Outer edge:
6 AU
Radius: 1.8 Rs

Mass: 1.9 MS

Surface Temp: 8250 ℃
More UV in the star’s light - between 2 to 10 times as much exposure in the star’s habitable zone, compared to Earth. X-ray levels are almost zero.
  • Broader habitable zone - allowing multiple Earth-like worlds.
  • Fewer damaging solar particle storms at habitable zone
  • Wider spaced solar system, with longer interplanetary travel times.
  • 2 to 10 times as much UV exposure for an Earth-like planet in the habitable zone
  • Habitable planets will be volcanic, younger.
The blue-white star (A5 type), as seen from a habitable planet: A5 type stars give a blue-tinged white light (true white as seen through an earth-like atmosphere), with a much higher surface temperature and luminosity than Earth’s Sun. Their habitable zones are generally further out so they appear smaller from any habitable planets - around a half to a fifth as wide as the Sun seen from Earth.

The daytime sky of a habitable planet: The sky of an Earth-like planet orbiting a type A star would (barring contaminants) be more intense blue, evn tending towards indigo, than Earth’s. Sunsets will be white, or very faint yellow.

The night sky of a habitable planet: Comets will show tails for longer than those orbiting our Sun, and auroras will be rare and fainter, owing to the weaker solar wind. Zodiacal light will be much brighter than Earth’s.

Other planets: Other planets will appear as star-like points. They may be considerably fainter than those seen from Earth, only changing positions against the background sky over terrestrial years or decades, as the system has room to be much more widely spaced.

Travel within the system:​

Travel methods and speeds:

Travel times from an orbit on the Habitable Zone’s (HZ) inner edge (2.7 AU) to one…

...on the Habitable Zone's outer edge (6 AU) ..with Mercury-like heat ( 1.5 AU):.. with Neptune-like cold (105 AU):
Chemical rocket speeds (by Hohman transfer orbit) Up to 25 km/sec*3 years 4 months
1 year 2 months140 years
Sublight probe/arkship speeds** 15,000 km/sec (5% lightspeed)9 hrs 10 min3 hrs 20 min12 days
At lightspeed 299,792 km/sec28 minutes10 minutes14 hrs 30 mins
*Higher velocity may be reached using manoeuvres such as gravitational slingshots, as today’s space probes do. Similarly, use of more fuel efficient routes may cause significantly longer travel times (as much as 10-20 times longer than a simple Hohman transfer path).
** Not factoring acceleration and deceleration time - see p??? [ link] for more explanation



Notes on the blue-white star (A-5 type star) and system:​


The blue-white (type A5) star: Type A5 stars are much larger and hotter than our Sun, with habitable zones further out so, despite being wider than the Sun they appear smaller from habitable planets. They are younger, and faster spinning, which affects their shape and pattern of surface brightness. They also lack a convective outer layer (see p??? [link}) , so the starspots and patterns of granules of sun-like stars may only occur at the equator. They live for a billion years (1/10th as long as our Sun) - time for simple life to arise, but multi-cell life is less likely. Under 1% of our galaxy’s stars are A type.

The surrounding system: The system is much broader than Earth’s, so planets may be much more widely spread - or you might in more: Multiple gas giants with large moon systems, and at least as many solid-surfaced worlds as our solar system has. The solid worlds are likely to be geologically active, with frequent powerful quakes and eruptions: Normal volcanoes occur on worlds in the HZ or closer, allowing even small worlds to have atmospheres. Icy worlds, further out, will have cryovolcanic (see p??? [link}) eruptions, bringing water and ammonia slurries to their surface. Interplanetary space in the system will have more asteroids and dust, a far weaker solar wind, with few particle storms. The orbits of outer giant planets may extend to hundreds of AU with years lasting terrestrial centuries, or even millenia. Habitable worlds will have years lasting terrestrial decades.

Visuals from an Earth-like planet in the habitable zone:​

The blue-white central star: The star itself could appear ½ to ¼, the Sun’s apparent size. The light tone is blue-tinged white, and it may appear slightly flattened, as its fast rotation pulls it into a tangerine shape. The rotation reduces the temperature and brightness of the equator, so the sun’s brightness (when viewable, for example through cloud or fog) will be concentrated at the poles. After passing through the atmosphere the star would appear less blue, more true-white.

Sky colour: The sky of an Earth-like planet orbiting a type A star would (barring contaminants) be brighter, stronger blue than Earth’s. Sunsets will be white, or very faint yellow. Blue sky is caused by the blue component of sunlight being scattered by the gas molecules making up our atmosphere - these are closer in size to the wavelength of blue light than the wavelength of red, so they scatter blue light much more efficiently across the sky. The same would happen for a world with an A type sun, but with less of a blue in its light the blue colour would be more intense.

Plant colour: Photosynthetic plants may be based on violet, yellow and red pigments, giving a red-purple colour to take advantage of the more blue-rich light.

Other sky phenomena: Aurora will be far rarer and fainter than Earth’s, owing to the lack of flares and CME particle storms. Comets will develop tails much further out, which will last longer, owing to the greater warmth from the star. The zodiacal light (see glossary, p??? [link]) will be brighter than Earth’s, creating a ‘false dawn’ effect.

Hazards: Interplanetary travel times will be longer, and would need more energy due to the central star’s higher gravity. UV exposure in the habitable zone will be 2-10 x higher, possibly driving life underground. Asteroids are more common, resulting in more impacts (see glossary, p??? [link]). The star itself, despite being calmer, is the greatest hazard, as ....

Here are the units of measurement used:

Units of measurement:


Mass:
  • 1 MS: 1 x our Sun’s mass​

  • 1 MJ : 1 x the planet Jupiter’s mass​

  • 1 ME: 1 x the planet Earth’s mass

Radius:
  • Rs: 1 x our Sun’s radius
  • Re: 1 x the Earth’s radius
  • Rj: 1 x Jupiter’s radius

Distances in space:
  • LD: Lunar Distance - The average gap between Earth and the Moon. 0.0026 AU or 400,000 km
  • AU: Astronomical Unit - about 150 million kilometres (93 million miles) or 8.3 light minutes
  • Light second: How far light travels through space in 1 second - 299792.4 km, or 0.002 AU
  • Light day: How far light travels through space in 1 day - 25,902,068,371.2 km or 173 AU
  • Light year: How far light travels through space in 1 year - 9,454,254,955,488,000 km, or 63,000 AU

Radiation:
For this booklet we are sticking to a single measure of radiation, the rad. However it's worth knowing that there are other measures in use, and they can be more complex than just 'rads mutiplied or divided by X number:
  • Rads: Unit of radiation dose - means: ‘1,000,000 joules of energy, in the form of radiation, has been absorbed by every kg of material’
  • Grey:
  • Sieverts:
 
This is interesting and provides a lot of details that an author could use after having decided on having a large, blue-white sun. Consider starting with a high-level matrix of different star types that would guide an author to select a specific type. Perhaps specify a maximum number of planets in the habitable zone and an average transit time between them. This could provide a reference to help choose a specific solar system configuration.
 
Another aspect to consider would rotational periods of planets within the habitable zone. The planets would not move in lockstep, so there will be periods where planets are more accessible and periods where planets are on opposite sides of the sun.
 
This is interesting and provides a lot of details that an author could use after having decided on having a large, blue-white sun. Consider starting with a high-level matrix of different star types that would guide an author to select a specific type. Perhaps specify a maximum number of planets in the habitable zone and an average transit time between them. This could provide a reference to help choose a specific solar system configuration.
Thanks @Wayne Mack, I have something of that nature at the beginning of the book - although it's based on star types and habitable zone width rather than number of planets: If Trappist-1 ( TRAPPIST-1 - Wikipedia ) can jam 4 worlds into its tiny habitable zone then, in principle, physics-wise, you could fit close to a hundred into the habitable zone of a star like our Sun and several hundred into the HZ of one of the star systems above - and I know that readers will wonder what the hell I'm on about if I use those numbers (and it's not clear from the collected observations what the actual average figures are yet).

Another aspect to consider would rotational periods of planets within the habitable zone. The planets would not move in lockstep, so there will be periods where planets are more accessible and periods where planets are on opposite sides of the sun
I've got a page in the 'General Notes' at the end of the book that goes into this, but I agree it could do with highlighting in the look-up sheet and accompanying notes - I can add a footnote:

Chemical rocket speeds (by Hohman transfer orbit***) Up to 25 km/sec*


*** Hohmann transfers require the planets to be in the correct positions along their orbits (as they do not move in lockstep), and so may only be used during certain time windows. See p?? in General notes for further details, and alternatives [link]

Although a Hohmann transfer is usually one of the most efficient options, there are others - but as I'm trying to keep this as accessible as possible to folks with a minimal background in physics and astronomy they will have to stay exiled to the General Notes section at the back of the book. I could put something about Hohmann transfers up near the front, to make sure the term is as clear as possible to the reader. TBH a proper run down on interplanetary travel is a book in its own right, and... oh dear I think I've just explained to myself why I need to add that to the 'to be written' list for this series...
 
I think this is great stuff, and would find it very usefull. I can't offer much in the terms of feedback, only it strikes me that it might work better coded into an application. In terms of target audience (I'm a wannabe writer with minimal physics and astronomy knowledge) then yes,it does the job for me.
Is '...may be much more widely spread - or you might in more: Multiple...' from The Surrounding System, Notes from a Blue White star a typo? (hope it is, otherwise I've no hope!)

Great work (y)
 
I think this is great stuff, and would find it very usefull. I can't offer much in the terms of feedback, only it strikes me that it might work better coded into an application. In terms of target audience (I'm a wannabe writer with minimal physics and astronomy knowledge) then yes,it does the job for me.
Is '...may be much more widely spread - or you might in more: Multiple...' from The Surrounding System, Notes from a Blue White star a typo? (hope it is, otherwise I've no hope!)

Great work (y)
Thanks for @AnRoinnUltra - yes, it's a typo (thank you for pointing it out), it should read: '...may be much more widely spread - or you might cram in more: Multiple...'
 

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