The competition to name the star HD38283 and the exoplanet orbiting it

Note that this blog post was rewritten to reflect that the planet has been named and the competition website has now been discontinued.

A southern-only star, with a planet discovered by an Australian astronomer at an Australian observatory – well of course it has to have an Australian name!

In August 2019, the Melbourne Age had an article about how the International Astronomical Union has asked Australia to name a planet, along with the star it’s orbiting.

But Planet McPlanetface? Oh, change the record. 

The competition

The star itself is pretty unassuming. It’s not visible with a naked eye, and currently only has a catalogue name - HD38283. But if you know where to look, and have a pair of low-power and large objective binoculars (say, a 7x50), you can actually see it. Being out of the city would help a lot, too, as it’d take a lot of finding. 

This is a screenshot from the free planetarium program Stellarium that shows HD38283 in relation to the Southern Cross and Carina. If you are going to find it using binoculars it's going to be tough. It's marked with the circle at the bottom left, in a small constellation called Mensa (the Table). Like the Southern Cross, if you’re in Australia, it never sets.

The planet that orbits HD38283 was discovered by Australian astronomer Chris Tinney at Siding Spring in NSW. It’s described as “Saturn-like”, meaning it’s a ball of gas rather than rock. The planet’s orbit is an oval, but it’s mostly in the star’s “Goldilocks” zone, meaning any moons around the planet could have liquid water. Yes, there are a lot of ifs, but potentially, these moons could support life.

This planet rejoiced in the name HD38283b. Hence the competition.

The Mount Burnett Observatory asked for suggestions for the name of the planet. People submitted their suggestions on a website, and a judging group choose a shortlist. The ultimate winner was chosen from this. 

And the name...?

The winning name for the star was Bubup, a word for child in the Boonwurrung language, a language from the Kulin nation in what is now Victoria. The chosen name for the plant orbiting Bubup was YanYan, another Boonwurrung word meaning a boy.

This is my own photo of newly-named star Bubup. I took this photo of the star from the Astronomical Society of Victoria's dark sky site. Bubup is the star in the very centre of the photo (which I’ve blown up on the right). The brighter star below this (which you notice is also red) is HD37993. At least this one has a name - WX Mensae. Not a great name, and certainly not as good as Bubup.

Of course, what you can see in the photo is the star itself. from Earth, you won’t be able to see YanYan the planet. Only the most sophisticated telescopes can see planets, and even then, only the largest planets. Anyone who has looked at Saturn will agree that planets are very very small objects. A medium sized planet orbiting a star 125 light years away? Just forget it. 

Discovering the planet

So how was it discovered? There are lots of different ways of detecting a planet, apart from seeing one directly. Most of these methods involved carefully observing the light from the star and seeing how it changes over time.

HD39293 was discovered using the so-called “Doppler spectroscopy” method. A star being orbited by a large planet doesn't just sit in one place, it wobbles back and forth as the planet goes around it. Sophisticated instruments can detect these regular wobbles by looking at changes in the star’s colour, even though they won’t be able to see the planet itself.

Another way is to watch the brightness of the star. If a large planet moves across the face of the star the star gets a smidge less bright for a while, then goes back to its normal brightness.