Epsilon Eridani - Revision history

Alastair: add category Stars_with_Planets

2018-05-27T20:52:14Z

add category Stars_with_Planets

Alastair: /* Fictional */

2017-07-12T02:04:27Z

Fictional

Alastair: /* Planets */ add correct name (Aegir) for planet b.

2017-06-18T20:49:54Z

Planets: add correct name (Aegir) for planet b.

Alastair: /* Planets */ add Mj

2017-06-18T07:40:36Z

Planets: add Mj

Alastair: /* Planets */ add grav

2017-06-18T07:38:02Z

Planets: add grav

Alastair: /* Planets */ adjust mass Spitzer for density ~5

2017-06-18T07:12:39Z

Planets: adjust mass Spitzer for density ~5

Alastair: /* Planets */ add table

2017-06-18T06:58:20Z

Planets: add table

Alastair: /* Fictional */ merge changes from private wiki

2017-06-18T06:02:54Z

Fictional: merge changes from private wiki

Alastair: /* Fictional */ add planet Spitzer reference

2017-02-26T05:10:50Z

Fictional: add planet Spitzer reference

Alastair: Created

2016-10-27T04:05:06Z

Created

New page

== Epsilon Eridani ==
=== Factual ===
[http://en.wikipedia.org/wiki/Epsilon_Eridani Epsilon Eridani] is a K2 star about ten-and-a-half light years from Earth, a bit cooler than our sun Sol and quite a bit younger (estimated to be about 800 million years, compared to our 4,500 million years). It features briefly in my novel ''The Chara Talisman''. It's nearest stellar neighbor is a binary pair of red dwarf flare stars, UV Ceti (also known as Luyten 726-8) at just over five light years, but TauCeti, home (in T-Space) to [[Jackie Roberts]] and the Port Skead spaceport in ''Chara Talisman'', is only a little further at five-and-a-half light years.

It's been known since 1998 to have at least one planet.. Astronomers deduced the planet's presence because of lumpiness in the cometary ring. As I write this on Oct 27 2008, NASA has [http://www.nasa.gov/mission_pages/spitzer/multimedia/20081027b.html announced] that observations from the Spitzer Space Telescope indicate that e Eridani has two asteroid belts, which strongly implies the presence of more planets.

[[Image:EpsEri-diagram.jpg|center|||Epsilon Eridani and Solar Systems Compared]]

The above diagram shows what we think we know, or think we know, about the system so far. None of that excludes the presences of smaller (Earth-sized) planets within the inner asteroid belt, closer to the star, because they'd be too small to detect.. My story isn't obsolete yet. Because ε Eri (as it's typically abbreviated) is cooler than our own sun, habitable planets would be closer. A planet at a distance equivalent to between Mercury and Venus would see ε Eri as about the brightness of our sun from Earth, although specific temperatures would depend on other factors too (greenhouse effect, for one).

=== Fictional ===

There are other story implications. This is a relatively young system (this is factual) with a lot of asteroidal material, and being young, there'll be isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system. Asteroid mining will be a major industry. Higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.

← Older revision		Revision as of 20:52, 27 May 2018
Line 1:		Line 1:
		+	[[Category:Stars_with_Planets]]
	== Epsilon Eridani ==		== Epsilon Eridani ==
	=== Factual ===		=== Factual ===

@@ Line 13: / Line 13: @@
 There are other story implications.  This is a relatively young system (this is factual) with a lot of asteroidal material,  and being young, there are isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system.  Asteroid mining is a major industry.  Somewhat higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.
-The outer reaches of the system (that is, a distance corresponding to the out reaches of the Solar System's Kuiper Belt or inner Oort cloud) contains scattered gas and dust clouds which can present a minor hazard to warp navigation.  Transit through such a cloud generally means a brief surge in background radiation, but unless something larger is struck, is relatively harmless, if alarming.
+The outer reaches of the system (that is, a distance corresponding to the out reaches of the Solar System's Kuiper Belt or inner Oort cloud) contains scattered gas and dust clouds which can present a minor hazard to warp navigation.  Transit through such a cloud generally means a brief surge in background radiation, but unless something larger is struck, is relatively harmless, although sometimes alarming.
 ==== History ====

@@ Line 35: / Line 35: @@
 |Spitzer||0.85||262||0.66 Me||0.9 Re||0.82g
 |-
-|b||3.39||2502 (6.85 yr)||493 Me (1.55 Mj)|| ||
+|Aegir (b)||3.39||2502 (6.85 yr)||493 Me (1.55 Mj)|| ||
 |-
 |d||~20||~97 yr|| >300 Me (0.94 Mj)|| ||

@@ Line 35: / Line 35: @@
 |Spitzer||0.85||262||0.66 Me||0.9 Re||0.82g
 |-
-|b||3.39||2502 (6.85 yr)||493 Me|| ||
+|b||3.39||2502 (6.85 yr)||493 Me (1.55 Mj)|| ||
 |-
-|d||~20||~97 yr|| >300 Me|| ||
+|d||~20||~97 yr|| >300 Me (0.94 Mj)|| ||
 |-
-|c||~34||~220 yr|| >100 Me|| ||
+|c||~34||~220 yr|| >100 Me (0.32 Mj)|| ||
 |}
 (Note: days and years above are Earth days/years)

@@ Line 33: / Line 33: @@
 !planet!!Distance(AU)!!Period(days)!!Mass!!Diameter!!Gravity
 |-
-|Spitzer||0.85||262||0.66 Me||0.9 Re||
+|Spitzer||0.85||262||0.66 Me||0.9 Re||0.82g
 |-
 |b||3.39||2502 (6.85 yr)||493 Me|| ||

← Older revision		Revision as of 06:58, 18 June 2017
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	The planet is smaller, cooler and dryer than Earth, but larger and wetter than Mars. The "barely habitable" is Roberts's opinion, but she comes from the overall warmer planet [[Skead]], orbiting [[Tau Ceti]].		The planet is smaller, cooler and dryer than Earth, but larger and wetter than Mars. The "barely habitable" is Roberts's opinion, but she comes from the overall warmer planet [[Skead]], orbiting [[Tau Ceti]].
		+
		+
		+	In the below table, planet b is confirmed, planets d and c are strongly suspected, and Spitzer is (so far as we know) fictional.
		+
		+	{\|class="wikitable"
		+	!planet!!Distance(AU)!!Period(days)!!Mass!!Diameter!!Gravity
		+	\|-
		+	\|Spitzer\|\|0.85\|\|262\|\|0.64 Me\|\|0.9 Re\|\|
		+	\|-
		+	\|b\|\|3.39\|\|2502 (6.85 yr)\|\|493 Me\|\| \|\|
		+	\|-
		+	\|d\|\|~20\|\|~97 yr\|\| >300 Me\|\| \|\|
		+	\|-
		+	\|c\|\|~34\|\|~220 yr\|\| >100 Me\|\| \|\|
		+	\|}
		+
		+	(Note: days and years above are Earth days/years)

@@ Line 11: / Line 11: @@
 === Fictional ===
-There are other story implications.  This is a relatively young system (this is factual) with a lot of asteroidal material,  and being young, there'll be isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system.  Asteroid mining will be a major industry.  Higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.
+There are other story implications.  This is a relatively young system (this is factual) with a lot of asteroidal material,  and being young, there are isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system.  Asteroid mining is a major industry.  Somewhat higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.
 ==== Planets ====
-There is one terraformed, but barely habitable, planet in the system.  It is named [[Spitzer]], after the space telescope which discovered the star's asteroid belts.  When we meet [[Jackie Roberts]] in ''[[The Chara Talisman]]'', she is on her way there.
+There is one terraformed, but "barely habitable", planet in the system.  It is named [[Spitzer]], after the space telescope which discovered the star's asteroid belts.  When we meet [[Jackie Roberts]] in ''[[The Chara Talisman]]'', she is on her way there.

← Older revision		Revision as of 05:10, 26 February 2017
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	There are other story implications. This is a relatively young system (this is factual) with a lot of asteroidal material, and being young, there'll be isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system. Asteroid mining will be a major industry. Higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.		There are other story implications. This is a relatively young system (this is factual) with a lot of asteroidal material, and being young, there'll be isotopes with relatively short half-lives that no longer exist (or exist in short supply) in the Solar system. Asteroid mining will be a major industry. Higher levels of background radiation will likely mean that life on the terraformed planet has mutated more than usual, with interesting results.
		+
		+	==== Planets ====
		+	There is one terraformed, but barely habitable, planet in the system. It is named [[Spitzer]], after the space telescope which discovered the star's asteroid belts. When we meet [[Jackie Roberts]] in ''[[The Chara Talisman]]'', she is on her way there.