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

SaturnRADIO INFRARED OPTICAL ULTRAVIOLET

Orion Nebula: Stars are born…RADIO INFRARED OPTICAL XRAY

Crab Nebula: a star that died in 1054RADIO OPTICAL XRAY

Cassiopeia A: a star that died in ~1700RADIO INFRARED OPTICAL XRAY

Sagittarius A: Mystery Mass in Galaxy CenterRADIO OPTICAL

Virgo A: Hidden Massive Black Hole shooting out a JetRADIO 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?

InterferometryGetting better “resolution”

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 27-element Very Large Array.

NRAO/AUI

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

• 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

Magnetic Fields in Active Galactic Nuclei