by Ann » Mon Mar 23, 2020 7:13 am
Got to show you a cool thing, or a cool star, in today's APOD.
Nu Eridani (blue star at upper left) and
40 Eridani (yellow-white star at lower right).
Start by looking at the bright blue star at upper left. That is Nu Eridani, probably the most massive star in today's APOD. Nu Eridani is classified as spectral class B2III SB, and
Jim Kaler's estimate is that the mass of Nu Eri is 8.5 solar masses.
Yes, but the really interesting star in the picture is the brightest yellow-white star at lower right. It is a K1V star, a main sequence star fainter and cooler than the Sun, and it is one of the few stars intrinsically fainter than the Sun that you might see with the naked eye. It is a nearby star, obviously, only 16 light-years away.
The star is 40 Eridani, also known as Keid, meaning egg shells. The bluish star to the upper right of it is called Beid, the eggs.
Anyway, the Keid system is a multiple one, containing a white dwarf and a tiny red dwarf. The white dwarf is a remnant of a star massive enough to have run through not only its main sequence but also its giant stage life and stopped producing energy by fusion, leaving only a hot but cooling stellar core behind. My own guess is that 40 Eridani B might have been perhaps a late type A or an F-type star when it was on the main sequence.
By the way, the white dwarf of the 40 Eridani system has been shown to be more massive than 0.5 M⊕. According to
this Astrobite, the mass of 40 Eridani B might be closer to 0.6 M⊕.
Ann
Got to show you a cool thing, or a cool star, in today's APOD.
[float=left][attachment=0]Beid Keid and Nu Eri.png[/attachment][c][size=85]Nu Eridani (blue star at upper left) and
40 Eridani (yellow-white star at lower right).[/size][/c][/float] [float=right][img3="The 40 Eridani system. The brightest star is a K1V main sequence star, 0.4 the luminosity of the Sun. 40 Eridani B is a white dwarf, and 40 Eridani C is a small red star similar to Proxima Centauri."]https://astrobites.org/wp-content/uploads/2017/09/featured-1024x1021.jpg[/img3][/float]
Start by looking at the bright blue star at upper left. That is Nu Eridani, probably the most massive star in today's APOD. Nu Eridani is classified as spectral class B2III SB, and [url=http://stars.astro.illinois.edu/sow/nueri.html]Jim Kaler's estimate[/url] is that the mass of Nu Eri is 8.5 solar masses.
Yes, but the really interesting star in the picture is the brightest yellow-white star at lower right. It is a K1V star, a main sequence star fainter and cooler than the Sun, and it is one of the few stars intrinsically fainter than the Sun that you might see with the naked eye. It is a nearby star, obviously, only 16 light-years away.
[float=right][img2]https://image.flaticon.com/icons/png/128/1476/1476347.png[/img2][/float]The star is 40 Eridani, also known as Keid, meaning egg shells. The bluish star to the upper right of it is called Beid, the eggs. :ssmile:
Anyway, the Keid system is a multiple one, containing a white dwarf and a tiny red dwarf. The white dwarf is a remnant of a star massive enough to have run through not only its main sequence but also its giant stage life and stopped producing energy by fusion, leaving only a hot but cooling stellar core behind. My own guess is that 40 Eridani B might have been perhaps a late type A or an F-type star when it was on the main sequence.
By the way, the white dwarf of the 40 Eridani system has been shown to be more massive than 0.5 M⊕. According to [url=https://astrobites.org/2017/09/12/40-eridani-b-a-challenging-star/]this Astrobite[/url], the mass of 40 Eridani B might be closer to 0.6 M⊕.
Ann