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September 2020: A Pair of Planets

September 2020

In the show this time, we talk to Andrew Tkachenko about Stellar astrophysics in the era of big data, Fiona Porter rounds up the latest news, and we find out what we can see in the September night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.

The News

In the news this month: intermediate mass mergers, telescope troubles, and a sighting of a much younger solar system.

First up, LIGO and VIRGO have spotted the gravitational waves of an unusual black hole merger. Since gravitational waves were first detected in 2015, a variety of astrophysical mergers have been seen between black holes and neutron stars. The most recent detection is unusual in the mass of the black holes involved – the pair were around 66 and 85 times the mass of the Sun, merging to form a black hole of around 142 solar masses.Next, some less good news – the Arecibo radio telescope in Puerto Rico is no longer able to operate as a result of recent damage. A steel cable that was used to support part of the telescope's structure snapped, breaking an antenna and tearing a 30-metre hole in the telescope's 302-metre dish.Finally, the Very Large Telescope in Chile has produced the first image of a pair of exoplanets around a Sun-like star. The star seen is very young – only about seventeen million years old – but is otherwise very similar to the Sun, with a comparable mass. The planets, however, are quite different to those in our own solar system: the inner planet weighs in at around fourteen times the mass of Jupiter, orbiting at 160 AU from its parent star, while the outer one is around six Jupiter masses and orbits at 320 AU. For comparison, 1 AU is the distance between the Earth and the Sun, and Pluto orbits at an average of 40 AU.Very few exoplanets have been directly imaged like this; the first one, also by the Very Large Telescope, was in 2004, and there are still less than 50 images total. Only two other systems with multiple planets have been imaged, and neither had a Sun-like star, so this is makes for a very interesting look at something like a much younger version of our solar system.

Interview with Andrew Tkachenko

Dr Andrew Tkachenko talks about his work on astroseismology and the use of machine learning for classifying groups of stars. In particular he discusses the TESS and Kepler missions and using light curves (plots of brightness against time) to classify stars with machine learning. He also introduces the planned PLATO mission as a future experiment this method will be useful on. Andrew also talks about what led him to Manchester and how the work he has been doing could be useful for a ground based survey that Manchester researchers Mark Kennedy and Rene Breton are involved in.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during September 2020.

Southern Hemisphere

Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speaks about the Southern Hemisphere night sky during September 2020.

Odds and Ends

George is organizing a professional workshop for UK postgraduate students who will be working with data from the Atacama Large Millimeter/submillimeter Array (ALMA). While George has organized workshops before, what makes this one different is that it will be virtual, which is a first for George. The advantages are that people can attend the workshop while staying home, so they do not need to take any health risks when travelling and also do not need to spend any money on train fare or hotel rooms. However, people will need to set up the data processing software CASA on their own computers as well as download the ALMA data that will be used for demonstration purposes during the workshop, and that could be more challenging if George and other ALMA staff are not physically present to help. The workshop will be sometime in the fall. Hopefully, it will go well.

Michael describes the QUBIC mission, one of many attempts to hunt for B-mode polarisation of the CMB. The collaboration has been working on a number of articles over the last few months. In particular a test of the prototype instrument in Paris was discussed. The preprint (as yet unpublished) version of that can be found here .

Show Credits

News:Fiona Porter
Interview:Andrew Tkachenko and Michael Wright
Night sky:Ian Morison and Haritina Mogosanu
Presenters:George Bendo and Michael Wright
Editors:Joseph Winnicki, Lizzy Lee and Hongming Tang
Segment Voice:Tess Jaffe
Website:Michael Wright and Stuart Lowe
Producer:Michael Wright
Cover art:This image, captured by the SPHERE instrument on ESO’s Very Large Telescope, shows the star TYC 8998-760-1 accompanied by two giant exoplanets, TYC 8998-760-1b and TYC 8998-760-1c. This is the first time astronomers have directly observed more than one planet orbiting a star similar to the Sun. CREDIT: ESO/Bohn et al.

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