Radio Stars

In April 2024, MIT Haystack Observatory hosted an international conference titled "Radio Stars in the Era of New Observatories" that was attended by more than 60 professional astronomers and other researchers from around the world. The meeting focused on how radio wavelength observations are being used to provide unique insights into the physics and evolution of the stars. Additionally, it showcased the latest advances in radio telescopes and other technologies that are enabling (or will soon enable) some of the most exciting discoveries in stellar astrophysics. In this episode, Radio Stars Producer Alex Griswold interviews several conference attendees to capture some of the scientific highlights from the meeting, as well as personal perspectives from those who participated.

Betelgeuse is a red supergiant star visible to sky watchers in the "shoulder" of the constellation of Orion, the Hunter. In late 2019 Betelgeuse began to undergo a surprising "dimming" event before recovering its typical brightness several months later. In this two-part podcast, hear how astronomers have been using observations at radio wavelengths, combined with data from other telescopes, to uncover the cause of this historic dimming event, and what it means for the future evolution of this star.

Betelgeuse is a red supergiant star visible to sky watchers in the "shoulder" of the constellation of Orion, the Hunter. In late 2019 Betelgeuse began to undergo a surprising "dimming" event before recovering its typical brightness several months later. In this two-part podcast, hear how astronomers have been using observations at radio wavelengths, combined with data from other telescopes, to uncover the cause of this historic dimming event, and what it means for the future evolution of this star.

Today we know that virtually all stars within our Galaxy emit radio waves. Using modern radio telescopes, astronomers routinely study these stellar radio waves to better understand how stars form, how they evolve, and how they die. However, for early radio astronomers, it was an enormous challenge to detect even the nearest radio star---the Sun. In this episode, we hear from astronomer and historian Dr. Ken Kellermann of the National Radio Astronomy Observatory about some of the pioneers of early radio astronomy, including Karl Jansky and Grote Reber, the challenges they faced, and how their work paved the way for current-day astronomers to use radio waves as a vital tool for understanding the astrophysics of Sun and other stars.

Even with the most powerful optical telescopes, the closest stars beyond the Sun generally appear as mere pinpoints of light, leaving us to only imagine what their light-emitting surfaces or "photospheres" might look like. However, using a technique known as radio interferometry, astronomers are now able to glimpse the faces of certain types of stars known as asymptotic giant branch stars (or "AGB stars" for short). What's more, the appearances of these AGB stars are seen to change over time. In this podcast, hear how astronomers are using radio interferometry to gain fascinating insights into what the future has in store for stars like the Sun as they reach old age.

Planetary nebulae form when a wind from a dying star blows away its outer layers, enveloping the star in a cloud of debris that can span many light years across. Often planetary nebulae have spectacularly complex shapes, leading to whimsical nicknames such as "Eskimo" or "Cat's Eye". However, the origin of these diverse shapes has been a long-standing puzzle; if the progenitor stars are spherical and lose mass uniformly in all directions, what sculpts their ejecta into these varied forms? Using observations of circumstellar radio waves, scientists are discovering that part of the answer is that the outflows from some dying stars are far more complex than once believed. This podcast explores how two types of radio wavelength observations of dying stars are being combined to offer new insights into the origin of the intricately-shaped stellar ejecta known as planetary nebulae.

As they near the end of their lives, stars like the Sun eventually deplete the supply of nuclear fuel in their cores. At this point, the outer layers expand and cool, until the star swells to as much as a hundred or more times its original size. Such stars are known as "red giants". Red giants are known to be rampant cosmic polluters, spewing large amounts of matter into space. In this podcast, learn how recent radio wavelength observations are leading to new insights into this process, including the discovery that some red giants are trailed by previously invisible wakes of debris up to several light years long!

For roughly a century, Cepheid variable stars have been used as a yardstick for measuring the scale of the universe. Cepheids undergo steady pulsations, causing their brightness to undergo regular variations. Because the exact period of these brightness fluctuations is tightly linked with the stellar luminosity, measurement of a Cepheid's period and apparent brightness provides a direct way to gauge its distance. But are the lives of Cepheids truly as regular and predictable as they seem? Learn in this podcast how recent radio and infrared observations have revealed that at least some Cepheids have a "dirty" secret: they are quietly spewing significant amounts of matter into space through stellar winds.