Episode 869
Herbig–Haro object
Sat, 2019-Sep-21 00:51 UTC
Length - 2:32
Direct Link
Welcome to featured Wiki of the Day where we read the summary of the featured Wikipedia article every day.
The featured article for Saturday, 21 September 2019 is Herbig–Haro object.
Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars. They are formed when narrow jets of partially ionized gas ejected by said stars collide with nearby clouds of gas and dust at speeds of several hundred kilometers per second. Herbig–Haro objects are commonly found in star-forming regions, and several are often seen around a single star, aligned with its rotational axis. Most of them lie within about one parsec (3.26 light-years) of the source, although some have been observed several parsecs away. HH objects are transient phenomena that last around a few tens of thousands of years. They can change visibly over quite short timescales of a few years as they move rapidly away from their parent star into the gas clouds of interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations have revealed the complex evolution of HH objects over the period of a few years, as parts of the nebula fade while others brighten as they collide with the clumpy material of the interstellar medium.
First observed in the late 19th century by Sherburne Wesley Burnham, Herbig–Haro objects were not recognized as being a distinct type of emission nebula until the 1940s. The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named. Herbig and Haro were working independently on studies of star formation when they first analysed the objects, and recognized that they were a by-product of the star formation process. Although HH objects are a visible wavelength phenomena, many remain undetectable at these wavelengths due to dust and gas envelope and can only be seen at infrared wavelengths. Such objects, when observed in near infrared, are called Molecular Hydrogen emission-line Objects (MHOs).
This recording reflects the Wikipedia text as of 00:51 UTC on Saturday, 21 September 2019.
For the full current version of the article, see Herbig–Haro object on Wikipedia.
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This has been Matthew. Thank you for listening to featured Wiki of the Day.
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