What is Radio Astronomy?
MIT Haystack Observatory
This material was developed under a grant from the National Science Foundation
The Electromagnetic Spectrum
• Spans a range of
wavelengths
• Visible is just a narrow
range
• Radiowaves span a
large range - from
under 1mm to several
meters
Sources of Radio emission
• Solar System - sun, planets
• Milky way - star forming regions, old stars,
supernova remnants
• Extragalactic - quasars, radio jets
• Molecules
Sun
OPTICAL
RADIO
XRAY
Saturn
RADIO INFRARED OPTICAL ULTRAVIOLET
Orion Nebula: Stars are born…
RADIO
INFRARED
OPTICAL
XRAY
Crab Nebula: a star that died in 1054
RADIO
OPTICAL
XRAY
Cassiopeia A: a star that died in ~1700
RADIO
INFRARED
OPTICAL
XRAY
Sagittarius A: Mystery Mass in Galaxy Center
RADIO
OPTICAL
Virgo A: Hidden Massive Black Hole shooting out a Jet
RADIO
OPTICAL
Molecules
What are molecules good for?
• Detections - newest one - “glycoaldehyde”
(sugar)
• Probes - measure temperature, density,
chemistry
• Kinematics - velocities - doppler effect
HC3N as a density probe
in the Taurus Molecular
Cloud (TMC-1)
CH3CCH as a temperature probe in TMC-1
Model of H2O maser emission around NGC4258
How do radio telescopes work?
What is Resolution?
Interferometry
Getting better “resolution”
NRAO/AUI
Compare the radio image on the right, made with the Haystack 37-m single dish
telescope at a frequency of 43 GHz with the radio image above made with the 27element Very Large Array.
VLBI images of SiO maser emission in Orion and a possible model
SiO Masers around a highly evolved star - R Cassiopeia
VLBI sequence of a supernova in M81
Magnetic Fields in Active Galactic Nuclei
• The Blazar 1055+018
– Active Galactic Nuclei
– 15 billion light years
distant
– AGN are 40 times more
luminous and 10,000
times larger than the
brightest “normal”
galaxies
– Displays a colossal jet of
relativistic plasma
– Powered by a
supermassive, rotating
black hole