Home > Astronomical History, Ephemeris Program, stars > 02/13/2017 – Ephemeris – The brightest night-time star has a tiny stellar companion

02/13/2017 – Ephemeris – The brightest night-time star has a tiny stellar companion

February 13, 2017

Ephemeris for Monday, February 13th.  The Sun will rise at 7:45.  It’ll be up for 10 hours and 23 minutes, setting at 6:08.  The Moon, 3 days past full, will rise at 9:16 this evening.

Sirius is the brightest night-time star and is located in the south at 9 p.m. below and a bit left of Orion the Hunter.  We’ve visited Sirius last week.  But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. It’s Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title.  The tiny star was suspected as far back as 1834 due to Sirius’ wavy path in the sky against the more distant stars.  Sirius is only 8 light years away.  Sirius A and the Pup have 50 year orbits of each other.  The star was first seen by Alvan Clark in 1862 while testing a new telescope.  The Pup was the first of a new class of stars to be discovered, white dwarfs.  The Pup is about the size of the Earth, with the mass of our Sun; its out of fuel and slowly collapsing.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Sirius' path

Sirius A & B’s path in the sky showing the wobble that betrayed the Pup’s presence. Credit Mike Guidry, University of Tennessee.

Sirius A and B

Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.

Orion's Belt points to Sirius

Orion’s Belt points to Sirius. Created using Stellarium.

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