Recording of webinar to celebrate 30 years of the Hubble Space Telescope

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    Dominic Ford

    This morning at midday, Dr John Mason presented a live webinar to celebrate the publication of an image by NASA to mark the 30th anniversary of the launch of the Hubble Space Telescope.

    Unfortunately we were unable to stream it live on YouTube, but you can now watch a video of the event here:

    External link:

    In the Q&A session, some technical questions came up which John needed to check with the specialists at NASA. Based on his conversations this afternoon, he would like to add the following:

    The image is nicknamed the “Cosmic Reef” because it resembles an undersea world.

    Although NGC 2014 and NGC 2020 appear to be separate in this visible-light image, they are actually part of one giant star formation complex in the Large Magellanic Cloud, about 163,000 light years distant.. The star-forming regions seen here are dominated by the glow of stars at least 10 times more massive than our Sun. These stars have short lives of from a few million to a few tens of millions of years, compared with the 10,000 million-year lifetime of our Sun.

    The blue-coloured nebula (NGC 2020) below NGC 2014 has been shaped by one mammoth star that is roughly 200,000 times more luminous than our Sun. It is an example of a rare class of stars called Wolf-Rayet stars, which have unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. Their surface temperatures typically range from 50,000 K to around 200,000 K, hotter than almost all other stars. They are thought to be the descendants of the most massive stars. Wolf-Rayet stars are very luminous and have a high rate of mass loss through powerful stellar winds. The star in the Hubble image is thought to be 15 times more massive than the Sun, although it may have been more massive in the past prior to shedding a considerable amount of its mass.

    The Wolf-Rayet star at the centre of NGC 2020 is unleashing powerful winds, which have cleared out the area around it. It has ejected its outer layers of gas, sweeping them around into a cone-like shape, and exposing its searing hot core. The star appears offset from the centre because the telescope is viewing the cone from a slightly tilted angle. In a few million years, the star is likely to explode as a supernova. The brilliant blue colour of the nebula comes from oxygen gas that is heated to roughly 11,000 degrees Celsius, which is much hotter than the hydrogen gas surrounding it.

    Information courtesy of NASA, ESA and STScI

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