Upload
feleti
View
79
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Interstellar Matter. Emily Linden & Fiona Ward. Question. Specify the radio techniques used to probe the nature of interstellar matter. Book example. Optical Spectral Analysis Requires -Background source of radiation - PowerPoint PPT Presentation
Citation preview
Emily Linden & Fiona Ward
INTERSTELLAR MATTER
Specify the radio techniques used to probe the nature
of interstellar matter.
QUESTION
• Optical Spectral Analysis Requires-Background source of radiation-Stars viewed through clouds to be relatively close to
earth (w/in a few thousand pcs)• Low-energy Radio Emissions produced by the gas of the
nebula itself is more versatile• Astronomers examine hydrogen spin-rates to determine
radio spectral lines• Hydrogen 21-Centimeter Radiation
BOOK EXAMPLE
• Hydrogen ground state spin patterns: parallel or antiparallel• Antiparallel has slightly less energy than parallel• All matter tends to achieve lowest possible energy state.• When hydrogen atom drops down to antiparallel spin, a
photon is emitted.• High energy low energy: Emitted photon is equal to energy
lost• Energy difference is very low, so energy of photon is very low• Wavelength= 21.1 cm (radio portion)• 21-centimeter radiation: the spectral line that results from
this hydrogen-spin-flip process
BOOK EXAMPLE
• Requires no visible light• Can be used on any interstellar region that
contains enough hydrogen gas to produce a detectable signal
• This includes low-density regions between dark clouds
• Wavelength much larger than typical interstellar dust particles
• Radio radiation reaches Earth unscattered by interstellar debris
• Can reach well beyond a few thousand parsecs• Can reach in directions lacking background
stars
BOOK EXAMPLE
• Hubble's Wide Field Planetary Camera 2 in 1994, 1995, and 2001
• Color filters were used to isolate light emitted by hydrogen, oxygen, nitrogen, and sulfur atoms
• This nebula is an emission
• NGC 604 (Nicolas-Claude Fabri de Peiresc.)
• First noted by the English astronomer William Herschel
ULTRAVIOLET, VISIBLE, AND
INFRARED
http://hubblesite.org/newscenter/archive/releases/2003/30/image/a/
• Radio signals will be sent out
• Usually up to five satellites in space
• Higher the frequency the father the distance
GRAVITATIONAL LENS
http://spectrevision.net/2013/05/31/interstellar-radio/
• Gives off a blue color• The star Rigel supplying
the light • Retains light from other
source
REFLECTION NEBULA
http://www.nasa.gov/multimedia/imagegallery/image_feature_701.html
• Book Example: Astronomers use Hydrogen 21-Centimeter Radiation to probe the nature of interstellar matter.
• Web Example: Astronomers use cameras from telescopes such as Hubble equipped with color filters and radio emissions to probe the nature of interstellar matter.
ANSWER