Unusual spectral types

[Arion]

I've put together a list of prominent stars with various details so that I can get familiar with what I am actually looking at.

However, there are some really odd spectral types listed for some of them, for which I wasn't even able to find a definition online. Anyone know what these mean?

Am/dM1e (Castor B )

A0mA1 Va (Sirius A)

[lenscap]

These links explain spectral classes.

Castor B itself is actually 2 stars, a class A star with enhanced metals (Am) and a dwarf class M1 star with emission lines (dM1e)

http://astronomy.swin.edu.au/cosmos/H/Harvard+Spectral+Classification

https://www.cfa.harvard.edu/~pberlind/atlas/htmls/note.html

hth

 

[robin_astro]

Sirius A is also a spectroscopic binary

Here is the paper by Richard Gray where he describes the A0mA1 Va classification for Sirius A

http://adsabs.harvard.edu/doi/10.1086/191237

Here he splits the V luminosity class (main sequence) into Va/Vb

Robin

[robin_astro]

1 hour ago, robin_astro said:

Sirius A is also a spectroscopic binary

At least SIMBAD reports it as such

http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+48915a

which was a surprise to me but I have not found any reference to it being so

[goodricke1]

On 26/07/2018 at 22:42, robin_astro said:

At least SIMBAD reports it as such

http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+48915a

which was a surprise to me but I have not found any reference to it being so

I'm pretty sure the spectroscopic binary being referred to is in fact Sirius A and the Pup. The spectroscope was used in this case to determine that the velocity of A is variable, and is in close agreement with the result derived from visual observation.

[robin_astro]

Perhaps, but there are separate entries in SIMBAD for Sirius (double or multiple star), Sirius A (spectroscopic binary), Sirius B (white dwarf).  The classification "spectroscopic binary" is normally used where a binary pair are not resolved or the companion is unseen (at least at the time of discovery) whereas the discovery of Sirius B predates astronomical spectroscopy and was first deduced from proper motion measurements and then found visually.

Maybe it refers to a long postulated third object which has now been discounted, though I believe evidence for that was also suspected anomalies in the proper motion  rather than spectroscopy

 

[goodricke1]

SIMBAD must be in error I'm sure. If Castor and Mizar can be famous examples of spectroscopic binaries, the brightest star in the sky would be much more represented in the literature if this were true.

[coatesg]

I think it refers to the (now disproven) 1995 paper that there was a small (brown dwarf mass) companion - see: http://adsabs.harvard.edu/abs/1995A&A...299..621B

Can't imagine the presence of anything very large is very likely (or at least something that isn't very close to A) - anything else probably wouldn't be in a very stable orbit, esp considering that B was previously a much larger star before evolving off the main sequence - the current upper observational limits on orbiting bodies in the system are quite small.