Astronomy Cast Full Raw Feed · Fraser Cain & Dr. Pamela L. Gay

Ep. 740: Sneaky Stars!

·1 hr 5 min·5 clips

Why a star that should have exploded six months ago is still hiding its nova from astronomers.

Fraser Cain and Dr. Pamela Gay host this episode of Astronomy Cast, focusing on the unpredictable nature of stars. The hosts discuss how stars often defy astronomers' expectations regarding their behavior and observable properties. They begin with the delayed nova of T Coronae Borealis, a recurrent nova expected to erupt last summer but still pending. Pamela Gay explains that with only about a century of detailed photometric data, astronomers are still learning what constitutes "normal" behavior for such stars. The irregularity might stem from changes in material transfer from its companion star, possibly due to the donor star's evolution or a depleted outer layer. The conversation highlights the lack of continuous, all-sky monitoring, a gap future telescopes like Vera Rubin will fill. They then examine Betelgeuse's unexpected dimming a few years ago, noting astronomers still debate whether it was caused by a giant sunspot or ejected dust. Current technology cannot definitively resolve surface features on such stars, though a proposed lunar interferometer could help. The hosts detail how stars can hide their true nature, like binary companions, especially when the stars are similar in temperature or not perfectly eclipsing. Pamela shares her early research on pulsating variable stars that unpredictably switch oscillation modes or "glitch," likely due to internal material shifts. Stellar composition can also be misleading, as stars may sink heavy elements internally or acquire them by consuming planets. Blue stragglers in globular clusters exemplify stellar deception, appearing young through collisions or mergers that reignite nuclear fusion. A key insight is that individual stars are often "lying liars," requiring population studies in clusters to discern general truths. The anticipated Vera Rubin Observatory will revolutionize time-domain astronomy by regularly surveying the entire southern sky. Even a star as prominent and close as Betelgeuse might have an unseen companion contributing to its light variations. The hosts emphasize that with limited historical data, what seems like anomalous stellar behavior might actually be routine over longer timescales. Technological limitations mean astronomers sometimes cannot distinguish between phenomena like dust clouds and starspots on distant giants. The tone is conversational and educational, blending personal anecdotes with detailed astronomical explanations. The hosts maintain a lighthearted rapport while delving into complex astrophysical concepts. This episode would appeal to astronomy enthusiasts interested in the challenges of observational science and the nuances of stellar astrophysics. Listeners seeking a highly structured, purely factual lecture might find the casual digressions less engaging.

As heard by us

A sharp look at star chemistry and how little a surface story can really settle.

The episode treats stellar chemistry as a clue, but it keeps undercutting the idea that the surface tells the full story. It lays out how elements can sink, mixing can be patchy, and a star can carry old damage from swallowing a planet or even another star.

Read the full review in PlayNext →

Why you'd press play

Press play for a star-chemistry mystery that keeps undercutting easy assumptions.

Read the full recommendation in PlayNext →

Listen to the show on

Apple Podcasts Spotify

Play clips from this episode More from Astronomy Cast Full Raw Feed