Difference between revisions of "Nebula"

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[[File:Comp-Prog-Dav-R-Deitrick-Starter-Trav-Page-16 16-July-2018a.jpg|right]]
 
[[File:Comp-Prog-Dav-R-Deitrick-Starter-Trav-Page-16 16-July-2018a.jpg|right]]
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A [[Nebula]] is an interstellar cloud of dust, hydrogen, helium and other ionized gases.
+
A [[Nebula]] is an interstellar cloud of dust, [[hydrogen]], helium and other ionized gases.
 
* Nebulae or nebulas can affect [[ship sensor suite]]s or other [[ship equipment]].  
 
* Nebulae or nebulas can affect [[ship sensor suite]]s or other [[ship equipment]].  
 
* They are [[Astrographic Feature]]s.
 
* They are [[Astrographic Feature]]s.
 
   
 
   
 
== Description ([[Specifications]]) ==
 
== Description ([[Specifications]]) ==
−
''[[Wikipedia: Interstellar cloud|Interstellar clouds]]'' are regions of gas, dust, and [[Wikipedia: plasma (physics)|plasma]] that have a higher average density than the general ''[[Wikipedia: Interstellar medium|interstellar medium]]''.  They are typically composed of about 70% hydrogen, the bulk of the remainder being helium with traces of other elements.  
+
''[[Wikipedia: Interstellar cloud|Interstellar clouds]]'' are regions of gas, dust, and [[Wikipedia: plasma (physics)|plasma]] that have a higher average density than the general ''[[Wikipedia: Interstellar medium|interstellar medium]]''.  They are typically composed of about 70% hydrogen, the bulk of the remainder being helium with traces of other elements. Nebula can range in size from as small as 1 pc in diameter, as in the case of planetary nebulae, to over 100 pc wide in the case of some of the largest nebular clouds.  
−
 
+
 
=== Basic Nebula Types ===
 
=== Basic Nebula Types ===
 
''[[Wikipedia: Interstellar cloud|Interstellar clouds]]'' can be classified into 3 general types based on the primary form of hydrogen found within:
 
''[[Wikipedia: Interstellar cloud|Interstellar clouds]]'' can be classified into 3 general types based on the primary form of hydrogen found within:
 
# ''Neutral Clouds'' ([[Wikipedia: H I region|H I regions]] - formed of atomic hydrogen)
 
# ''Neutral Clouds'' ([[Wikipedia: H I region|H I regions]] - formed of atomic hydrogen)
−
# ''Ionized Clouds'' ([[Wikipedia: H II region|H II regions]] - formed of ionized hydrogen [i.e. "[[Wikipedia: plasma (physics)|Plasma]]"])
+
# ''Ionized Clouds'' ([[Wikipedia: H II region|H II regions]] - formed of positively-ionized hydrogen [i.e. "[[Wikipedia: plasma (physics)|Plasma]]"])
 
# ''[[Wikipedia: Molecular cloud|Molecular Clouds]]'' (Molecular Hydrogen - formed of H<sub>2</sub>)
 
# ''[[Wikipedia: Molecular cloud|Molecular Clouds]]'' (Molecular Hydrogen - formed of H<sub>2</sub>)
  
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=== Selected Nebulae ===
 
=== Selected Nebulae ===
  
 +
# [[Anellet Cloud]]
 +
# [[The Anundarluu|Anundarluu, The]]
 +
# [[Anterior Cloud]]
 
# [[Basilisk Nebula]]
 
# [[Basilisk Nebula]]
 
# [[Block Nebula]]
 
# [[Block Nebula]]
 +
# [[Bourne Cloud]]
 +
# [[The Cauldron]]
 
# [[Coalsack Nebula]]
 
# [[Coalsack Nebula]]
 
# [[Curtain Nebula]]  
 
# [[Curtain Nebula]]  
−
# [[Lesser Curtain Nebula]]  
+
# [[Lesser Curtain Nebula|Curtain Nebula, Lesser]]  
 
# [[Dark Cloud]]
 
# [[Dark Cloud]]
−
# [[The Dark Nebula]]
+
# [[The Dark Nebula|Dark Nebula, The]]
 +
# [[Deimos Cloud]]
 
# [[Demon's Eye Nebula]]
 
# [[Demon's Eye Nebula]]
 
# [[Helix Nebula]]
 
# [[Helix Nebula]]
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# [[Hook Nebula]]
 
# [[Hook Nebula]]
 
# [[Horsehead Nebula]]
 
# [[Horsehead Nebula]]
 +
# [[Magister Cloud]]
 
# [[Inferno Nebula]]
 
# [[Inferno Nebula]]
 +
# [[Orion Nebula]]
 
# [[North American Nebula]]
 
# [[North American Nebula]]
 
# [[Pelican Nebula]]
 
# [[Pelican Nebula]]
 +
# [[Phobos Cloud]]
 
# [[Rim Reach Nebula]]
 
# [[Rim Reach Nebula]]
−
# [[Greater Shell Nebula]]
+
# [[Greater Shell Nebula|Shell Nebula, Greater]]
−
# [[Lesser Shell Nebula]]
+
# [[Lesser Shell Nebula|Shell Nebula, Lesser]]
 
# [[Separe Cloud]]
 
# [[Separe Cloud]]
 +
# [[Shadow Cloud]]
 
# [[Spark Nebula]]
 
# [[Spark Nebula]]
 +
# [[Great Ulund Cloud|Ulund Cloud, Great]]
 +
# [[Little Ulund Cloud|Ulund Cloud, Little]]
 +
# [[Veil of The Rim]]
 
# [[Verant's Head Nebula]]
 
# [[Verant's Head Nebula]]
 +
# [[Wisp Cloud]]
  
 
== History & Background ([[Dossier]]) ==
 
== History & Background ([[Dossier]]) ==
−
No information yet available.  
+
Ancient [[Solomani]] astronomers originally used the [[Latin]] term "[[Nebula]]" (''Lat. "Cloud"'') to refer to any diffuse object observed in the night skies of Ancient [[Terra]]. These included what were termed "nebulous stars" at the time (which included both what were later discovered to be star clusters and nebulae proper) as well as what were later discovered to be galaxies before their true nature was known.  Numerous astronomical catalogs were published by different [[Terran]] observers over a long span of time, which included among their lists objects originally classified as "nebulae". Such catalogs included the ''Messier Catalog'' of Charles Messier (abbr. "'''M'''", which was later supplemented by the the ''Caldwell Catalog'' (abbr. "'''C'''")), and the ''New General Catalog of Nebulae and Clusters of Stars'' (abbr. "'''NGC'''"), with the "''Index Catalog of Nebulae and Clusters of Stars''" (abbr. "'''IC'''") as an associated later supplement, among others. 
 +
 
 +
* Known to Vilani science
  
 
=== Nebula Effects on Ships ===
 
=== Nebula Effects on Ships ===
−
Nebulae often interfere with [[sensor]]s, especially commercial [[ship sensor suite]]s. They can affect other [[ship equipment]] as well.
+
Nebulae often interfere with [[sensor]]s, especially commercial [[ship sensor suite]]s. They can affect other [[ship equipment]] as well.{{Unpublished cite|author= Maksim-Smelchak }} Sufficient study by astronomers will allow jumping into and out of the better known nebulae. There's still enough clutter that an [[astrogator]] has to aim for the destination's outer reaches.{{Unpublished cite|author= [[Tom Chlebus]] }} [[Misjump]]s are a strong possibility under many to most conditions.{{Unpublished cite|author= Maksim-Smelchak }}
 +
 
 +
''[[Old Spacer's Tale|Old Spacer's Comments]]:'' A nebula is quite impressive from a distance, but usually doesn't look like much close-up. The gas and dust in the typical nebula are actually very sparse, barely more dense than a pure [[vacuum]]. They look impressive from a distance only because they're so deep along our line of sight. Many [[spacer]]s have reported that fuel skimming from a nebula would be about as effective as collecting water by running through fog with a bucket. Under most conditions, it would degrade [[sensor]]s beyond a few dozen [[AU]]. [[NAFAL]] (>0.1c) travel would be hazardous; but it wouldn't ordinarily affect jump nor could it be efficiently skimmed without something like a electro-magnetic ramscoop. {{Unpublished cite|author= [[William A. Humphrey]] }}
  
−
=== Nebula Sizes ===
+
=== Nebula Size & Relative Location ===
 
Nebulae are typically measured in the following units:
 
Nebulae are typically measured in the following units:
 
{| class="wikitable sortable"  
 
{| class="wikitable sortable"  
−
!colspan="5"|Nebula Size & Location
+
!colspan="5"|Nebula Size & Relative Location
 
|-
 
|-
 
! Size
 
! Size
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| [[Astrographic Hex]]
 
| [[Astrographic Hex]]
 
| [[Parsec]] or [[AU]]
 
| [[Parsec]] or [[AU]]
−
| Smaller nebulae typically represented on a single astrographic hex.
+
| These smaller nebulae are typically represented on a single astrographic hex.
 
|-
 
|-
 
| [[Subsector]]
 
| [[Subsector]]
 
| [[Light-year]] or [[Deshi]]
 
| [[Light-year]] or [[Deshi]]
−
| Smaller nebulae by astronomic standards, but less than a subsector in size.
+
| They are smaller nebulae by astronomic standards, but less than a subsector in size.
 
|-
 
|-
 
| [[Sector]]
 
| [[Sector]]
 
| [[Light-year]] or [[Deshi]]
 
| [[Light-year]] or [[Deshi]]
−
| Typical nebulae, often several subsectors in size. Some might be proto-galaxies, failed galaxies, or accreted star clusters... possibly the remants of a nova starburst.  
+
| These are typical nebulae, often several subsectors in size. Some might be proto-galaxies, failed galaxies, or accreted star clusters... possibly the remants of a nova starburst.  
 
|-
 
|-
 
| Multi-Sector
 
| Multi-Sector
 
| [[Light-year]] or [[Deshi]]
 
| [[Light-year]] or [[Deshi]]
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| Truly massive nebulae, often several sectors in size.
+
| These are truly massive nebulae, often several sectors in size.
 
|-
 
|-
 
|}
 
|}
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{{Detail}}
 
{{Detail}}
 
{{Sources
 
{{Sources
−
|S1= TBD
 
 
|S2= [[Traveller Wiki Editorial Team]]
 
|S2= [[Traveller Wiki Editorial Team]]
 
|S3= Author & Contributor: [[User:WHULorigan|WHULorigan]]
 
|S3= Author & Contributor: [[User:WHULorigan|WHULorigan]]

Revision as of 17:30, 23 January 2019

Comp-Prog-Dav-R-Deitrick-Starter-Trav-Page-16 16-July-2018a.jpg

A Nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases.

Description (Specifications)

Interstellar clouds are regions of gas, dust, and plasma that have a higher average density than the general interstellar medium. They are typically composed of about 70% hydrogen, the bulk of the remainder being helium with traces of other elements. Nebula can range in size from as small as 1 pc in diameter, as in the case of planetary nebulae, to over 100 pc wide in the case of some of the largest nebular clouds.

Basic Nebula Types

Interstellar clouds can be classified into 3 general types based on the primary form of hydrogen found within:

  1. Neutral Clouds (H I regions - formed of atomic hydrogen)
  2. Ionized Clouds (H II regions - formed of positively-ionized hydrogen [i.e. "Plasma"])
  3. Molecular Clouds (Molecular Hydrogen - formed of H2)

Hydrostatic Equilibrium

Under normal circumstances interstellar clouds exist in a state of hydrostatic equilibrium, in which the natural self-gravitation that would otherwise cause the cloud to collapse is balanced by the outward pressure within the cloud due to motion of the atoms and molecules that compose it. Star formation is normally caused within molecular clouds by a triggering event which locally disturbs this equilibrium, causing runaway local collapsing regions within the cloud. Such causes can be the collision of one cloud with another, or the shock-wave within the interstellar medium caused by a nearby supernova explosion.

Selected Nebulae

  1. Anellet Cloud
  2. Anundarluu, The
  3. Anterior Cloud
  4. Basilisk Nebula
  5. Block Nebula
  6. Bourne Cloud
  7. The Cauldron
  8. Coalsack Nebula
  9. Curtain Nebula
  10. Curtain Nebula, Lesser
  11. Dark Cloud
  12. Dark Nebula, The
  13. Deimos Cloud
  14. Demon's Eye Nebula
  15. Helix Nebula
  16. Holowon Cloud
  17. Hook Nebula
  18. Horsehead Nebula
  19. Magister Cloud
  20. Inferno Nebula
  21. Orion Nebula
  22. North American Nebula
  23. Pelican Nebula
  24. Phobos Cloud
  25. Rim Reach Nebula
  26. Shell Nebula, Greater
  27. Shell Nebula, Lesser
  28. Separe Cloud
  29. Shadow Cloud
  30. Spark Nebula
  31. Ulund Cloud, Great
  32. Ulund Cloud, Little
  33. Veil of The Rim
  34. Verant's Head Nebula
  35. Wisp Cloud

History & Background (Dossier)

Ancient Solomani astronomers originally used the Latin term "Nebula" (Lat. "Cloud") to refer to any diffuse object observed in the night skies of Ancient Terra. These included what were termed "nebulous stars" at the time (which included both what were later discovered to be star clusters and nebulae proper) as well as what were later discovered to be galaxies before their true nature was known. Numerous astronomical catalogs were published by different Terran observers over a long span of time, which included among their lists objects originally classified as "nebulae". Such catalogs included the Messier Catalog of Charles Messier (abbr. "M", which was later supplemented by the the Caldwell Catalog (abbr. "C")), and the New General Catalog of Nebulae and Clusters of Stars (abbr. "NGC"), with the "Index Catalog of Nebulae and Clusters of Stars" (abbr. "IC") as an associated later supplement, among others.

  • Known to Vilani science

Nebula Effects on Ships

Nebulae often interfere with sensors, especially commercial ship sensor suites. They can affect other ship equipment as well.[1] Sufficient study by astronomers will allow jumping into and out of the better known nebulae. There's still enough clutter that an astrogator has to aim for the destination's outer reaches.[2] Misjumps are a strong possibility under many to most conditions.[3]

Old Spacer's Comments: A nebula is quite impressive from a distance, but usually doesn't look like much close-up. The gas and dust in the typical nebula are actually very sparse, barely more dense than a pure vacuum. They look impressive from a distance only because they're so deep along our line of sight. Many spacers have reported that fuel skimming from a nebula would be about as effective as collecting water by running through fog with a bucket. Under most conditions, it would degrade sensors beyond a few dozen AU. NAFAL (>0.1c) travel would be hazardous; but it wouldn't ordinarily affect jump nor could it be efficiently skimmed without something like a electro-magnetic ramscoop. [4]

Nebula Size & Relative Location

Nebulae are typically measured in the following units:

Nebula Size & Relative Location
Size Typical Metrics Remarks
Astrographic Hex Parsec or AU These smaller nebulae are typically represented on a single astrographic hex.
Subsector Light-year or Deshi They are smaller nebulae by astronomic standards, but less than a subsector in size.
Sector Light-year or Deshi These are typical nebulae, often several subsectors in size. Some might be proto-galaxies, failed galaxies, or accreted star clusters... possibly the remants of a nova starburst.
Multi-Sector Light-year or Deshi These are truly massive nebulae, often several sectors in size.

References & Contributors (Sources)

62px-Information icon.svg.png This article is missing content for one or more detailed sections. Additional details are required to complete the article. You can help the Traveller Wiki by expanding it.
This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.
  1. ↑ Information provided to the library by Maksim-Smelchak
  2. ↑ Information provided to the library by Tom Chlebus
  3. ↑ Information provided to the library by Maksim-Smelchak
  4. ↑ Information provided to the library by William A. Humphrey
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