A Star Named Melville

15 Feb 2021

Everyone knows Sigma Octantis, our southern pole star that lies slightly more than one degree from the south celestial pole, albeit at the dim end of fifth magnitude (5.47, nearly sixth) one has to look quite hard to find it.

But how many of us have ever heard of a star named Melville that lies even closer to the south celestial pole?

I came across reference to this charmingly named star years ago in a catalogue compiled by the Scottish astronomer Thomas Henderson. His catalogue “Positions of stars near the South Pole for the beginning of 1832”, contains this beguiling note about one of the stars: “The star whose right ascension is 19h31m, and which is within 27 minutes of the pole, was frequently observed by Mr. Fallows and is named Melville in his observations.”

Melville?

Melville the star’s story began in 1820 when a British mathematician with the swashbuckling name of Fearon Fallows was appointed by the British Admiralty to be the astronomer at the Cape of Good Hope, which would involve overseeing the building of an observatory in what was then a British colony. Between 1821 and 1829 he worked to site, plan and develop the observatory, which was the first astronomical observatory in the southern hemisphere.

He, and all the observatory staff, caught scarlet fever in 1830. (Scarlet fever is a contagious bacterial infection that mostly affects young children. These days it’s easily treated with antibiotics, but in the 1800s it caused deadly epidemics.) While still director of the observatory, he died of the disease in Simon’s Town, South Africa, in 1831 at the age of forty-three. He was buried on the grounds of the observatory, where his grave can still be seen. Despite his early death, his contribution to astronomy was considerable, cataloguing nearly 300 stars from his observations at the Cape.

Robert Saunders Dundas, second Viscount Melville (1771-1851) was the First Lord of the Admiralty from 1812 to 1827, and from 1828 to 1830. Apparently, even out of tight budgets, he never failed to squeeze something for another scientific interest or exploration… which was clearly appreciated by Fallows!

*Left – Fearon Fallows (1788-1831). Right – Melville (1771-1851)*

Observing Melville and the SCP

16″ f4.5 Dobs; 90x, 130x, 228x and 333x

Melville is a very interesting star, its name not withstanding. It is an S-type star, which is a cool giant with approximately equal quantities of carbon and oxygen in its atmosphere. The class was originally defined in 1922 by Paul Merrill for stars with unusual absorption lines and molecular bands now known to be due to s-process elements. The bands of zirconium monoxide (ZrO) are a defining feature of the S stars.

And what fun it is to rummaged around the faint stars in the vicinity of the south celestial pole both identifying Melville and also having a look at the place in the sky that marks our south pole.

This famously known, but unknown invisible spot in the sky, forms an equilateral triangle with 6.8 magnitude Melville (to the west) and the brightest of a trio of stars in a gentle arc of descending brightness – 7.8 mag HD 99685 being at the southern end of the arc. The other two stars are 8.7 mag HD 98784 in the middle of the arc and 11.5 mag TYC 9505-21-1.

I confess that without its tremendous name, HD 110994 would have remained but a random star that helped mark the south pole. But its tremendous name has elevated in my eyes to a most special star, to be visited now and then.