MXPlank News Letter - 2021-07-26

Globular Cluster NGC 1466

This image from the NASA/ESA Hubble Space Telescope reveals an ancient, glimmering ball of stars called NGC 1466. It is a globular cluster - a gathering of stars all held together by gravity - that is slowly moving through space on the outskirts of the Large Magellanic Cloud, one of our closest galactic neighbours.

NGC 1466 certainly is one for extremes. It has a mass equivalent to roughly 140 000 Suns and an age of around 13.1 billion years, making it almost as old as the Universe itself. This fossil-like relic from the early Universe lies some 160 000 light-years away from us.

NGC 1466 is one of the 5 clusters in the LMC in which the level of dynamical evolution (or "dynamical age") was measured.

Credit:
ESA/Hubble & NASA

Exoplanet orbiting two stars

This image shows a gas giant planet circling the two red dwarf stars in the system OGLE-2007-BLG-349, located 8 000 light-years away. The planet - with a mass similar to Saturn - orbits the two stars at a distance of roughly 480 million kilometres. The two red dwarf stars are a mere 11 million kilometres apart.

The image is based on observations made with Hubble that helped astronomers confirm the existence of a planet orbiting The two stars in the system.

The system is too far away for Hubble to take an image of the planet. Instead, its presence was inferred from gravitational microlensing. This phenomenon occurs when the gravity of a foreground star bends and amplifies the light of a background star that momentarily aligns with it. The particular character of the light magnification can reveal clues to the nature of the foreground star and any associated planets. The Hubble observations represent the first time such a three-body system has been confirmed using the gravitational microlensing technique.

Credit:
NASA, ESA, and G. Bacon (STScI)

The Eponymous NGC 691

This image features the spiral galaxy NGC 691, imaged in fantastic detail by Hubble’s Wide Field Camera 3 (WFC3). This galaxy is the eponymous member of the NGC 691 galaxy group, a group of gravitationally bound galaxies that lie about 120 million light-years from Earth.

Objects such as NGC 691 are observed by Hubble using a range of filters. Each filter only allows certain wavelengths of light to reach Hubble’s WFC3. The images collected using different filters are then coloured by specialised visual artists who can make informed choices about which colour best corresponds to which filter. By combining the coloured images from individual filters, a full-colour image of the astronomical object can be recreated. In this way, we can get remarkably good insight into the nature and appearance of these objects.

Stellar flare hits HD 189733b

This image shows exoplanet HD 189733b, as it passes in front of its parent star, called HD 189733A. Hubble's instruments observed the system in 2010, and in 2011 following a large flare from the star (depicted in the image). Following the flare, Hubble observed the planet's atmosphere evaporating at a rate of over 1000 tonnes per second. In this picture, the surface of the star, which is around 80% the mass of the Sun, is based on observations of the Sun from the Solar Dynamics Observatory.

Credit:
NASA, ESA, L. Calcada

MXPlank News Letter - 2021-07-26

Globular Cluster NGC 1466

Exoplanet orbiting two stars

The Eponymous NGC 691

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Stellar flare hits HD 189733b