Gamma Ray Bursts

At the bottom of this entry, I give the Weekly Pondering 6 assignment, for those of you in ASTR 1/2. Any text that you need to read is linked to here.

6: Gamma Ray Bursts

Since we have been learning about the stars, we have come across a panoply of types. Some stars are tiny and cool--such as the most common type, the red dwarf. An example of such a star is Bernard’s star. Then there are the enormous blue giants. These are the brightest stars in the universe, but also very rare. An example of such a star is HD 269810, which is about 2.19 million times as luminous as the Sun, and 130 times as massive [1]. On Earth, we get enough sunlight per square meter on average to power [2] about 23 60-Watt light bulbs. If we replaced our Sun with HD 269810, a 100 x 100 m area of the Earth would receive enough light per second to power about 800 average [3] US households for a year. Actually, Earth would be so irradiated that it would become a desolate and hot rock.

We are also learning about how stars die. The most massive stars die in the most spectacular fashions, with huge fusion explosions called supernovae. We have observed many supernovae in our universe, although per galaxy they are quite rare. In this WP assignment we will learn about massive bursts of gamma radiation, with lower-energy afterglows, that were discovered by accident in the 1960s. We call these gamma ray bursts, and they continue to perplex us. The are so powerful that they typically release more energy [4] in 40 seconds than the Sun will in 10 billion years, and, although the evidence currently suggests that most of them are associated with supernovae, no consistent model of how these bursts form has been established. Please read this article (there are nine pages) on gamma ray bursts and watch the two short videos embedded above. In a paragraph or two, state three aspects of gamma ray bursts that you find interesting and remarkable. They could be observations, and/or questions you have.

Submit WP 6 here:

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Bibliography

1. Evans, C. J., et al. "A massive runaway star from 30 Doradus." The Astrophysical Journal Letters 715.2 (2010): L74.

2. Kopp, Greg, and Judith L. Lean. "A new, lower value of total solar irradiance: Evidence and climate significance." Geophysical Research Letters 38.1 (2011).

3. Use of Energy Explained; site: https://www.eia.gov/energyexplained/use-of-energy/electricityuse-in-homes.php. Accessed: March 2021; Note: this site provides household energy use; the computation for HD 269810 is my own work.

4. Massive star's dying blast caught by rapid-response telescopes; site: https://phys.org/news/2017-07-massive-star-dying-blast-caught.html. Accessed: March 2021