The latest in Ph-word: July and August’21

Do you want to know what happened during the hot months? The jet from the black hole in the centre of a nearby galaxy was photographed, the asteroid that flies closest to the sun was found, and a new kind of supernova was observed. That’s it. You can now stop reading. Just joking, you can read the whole of this brief astro-full post.


The Event Horizon Telescope, of first-photo-of-a-black-hole fame, analyzed data that it had from looking at the centre of galaxy Centaurus A. (Whose distance of 13 million light years away from us practically makes it a neighbour.) What it was after was the jets of gas launched from it. The jets have been photographed before, but now the ‘Scope took a much more clear look close to where they begin.


2021PH27 is a small asteroid which gets really close to the sun. 2021PH27 can get as close as 20 million kilometres from it, while Mercury gets to 47 million.

The small rock is one kilometer wide and was found by astronomer Scott Sheppard while looking at images from the Victor M. Blanco telescope. All in all, this makes the asteroid the closest celestial body to the sun, excepting a few comets.



When stars that are lighter than about eight solar masses run out of nuclear fuel, they become white dwarfs which can sometimes explode in a supernova. When stars heavier than ten solar masses run out of fuel, they explode in a (different kind of) supernova and then turn into either neutron stars or black holes.

Now, a third kind of supernova, applicable to the mass range between eight and ten solar masses, was caught on camera. This type and its features were predicted several years ago, and now they were seen to fit the behaviour of supernova SN2019zd, some 30 million light years away, which was captured misbehaving by the Hubble and the Spitzer telescopes.

The novel type is called electron-capture supernova. The idea here is that when the star stops producing energy it starts collapsing, and this presses electrons onto atomic nuclei. Eventually things become too narrow and the star explodes.

The new supernova (blue dot) in its host galaxy.
NASA/STScI/ J. DePasquale/ Las Cumbres Observatory

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