habitable terrestrial exoplanet
DESCRIPTION
Habitable Terrestrial Exoplanet. Search for terrestrial planets around M dwarfs → larger reflex motion Smaller stellar mass Habitable zone closer (TRANSCRIPT
04/19/23 AST 248, Spring 2007 1
Habitable Terrestrial Exoplanet
• Search for terrestrial planets around M dwarfs → larger reflex motion– Smaller stellar mass– Habitable zone closer (<0.1 AU): does not mean
planet is there– Circularization: eccentricity may be small
• Gliese 581: previously known to have Neptune-mass planet
• 2 new planets: one with no eccentricity• Deduced mean planetary temperature: 0–40 C
(depends on reflectivity)
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Gliese 581 Parameters
Parameter Gl 581 b Gl 581 c Gl 581d
P [days] 5.3684
0.0004
12.93 0.008
84.4
0.6
e 0 (fixed) 0 (fixed) 0.20
0.09
a [AU] 0.041 0.073 0.25
m sin i [M] 15.7 5.1 8.2
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Search for Life in the Universe
Chapters 12 (Part 2)
Unidentified Flying Objects (UFOs)
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Outline• UFOs
– Crashed Aliens in Roswell, NM– Crop Circles, Abductions, etc.– Ancient Visitations– Cover-Up & Scientific Disinterest
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UFOs
• Appearance– Jet planes first introduced at the end of World War II
public aware of fast-moving aircrafts– First UFO claim in June 1947– “Flew erratic, like a saucer” flying saucer– ~50% of the public believe in the existence of UFOs
• Air Force Investigation– 20-year investigation– 90% of claims discarded– Remaining 10% indeterminate– Lack of proof is no proof
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Crashed Aliens in Roswell, NM
• Known facts– Rancher found crash remnants July 1947– Military personnel picked up the debris– Remains shown next day in Fort Worth, TX– Claimed to be remains of a weather balloon
• Claims by Stanton Friedman (1978)– Crash an alien spacecraft– Alien bodies also recovered– Story hushed up by military
• Analysis– Project Mogul: balloon used for secret monitoring of Soviet tests– Witness accounts in seventies contradicted or discounted– Motive for secrecy not clear– Ability to keep secret highly doubtful
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Crop Circles, Abductions, etc.
• Crop circles:– Claim: too accurate and too quick to be done
by humans– Shown to be possible– Some admitted to be pranks
• Abductions:– Sleep paralysis: common dream during rapid
eye movement (REM)– Also known during day dreaming
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Ancient Visitations
• Ancient drawings– Claim: pictures of aliens– Counterclaim: other possibilities abound
• Nazca markings– Claim: needed unavailable knowledge– Counterclaim: did not need unavailable knowledge– Claim: could only be seen from space– Counterclaim: could be form of worship
• Egyptian pyramids– Claim: Egyptians could not build the pyramids by themselves– Counterclaim: it was shown that the pyramids could be
constructed with tools available then
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Cover-Up & Scientific Disinterest
• Cover-up– Motive to avoid alarm: 50% already think that aliens
have landed– U.S. Government notoriously unable to keep secrets
known by many for a long time– All other governments need to participate in the
conspiracy
• Scientific disinterest– Stems from lack of evidence, not disinterest– If there was serious evidence, or the chance to obtain
serious evidence, scientists would jump at it