This was my second spectrum accepted into the BeSS database. It is a high resolution spectrum I just obtained of the H alpha region of the Be star (B emission) HD43544. This is a 6th magnitude star in the well known Winter constellation Canis Major. Captured with the Lhires III spectrograph, C14, Atik 460EX, Paramount ME from Las Cruces, NM. Many B spectral type stars exhibit emission lines rather than absorption (meaning they spike upward , not downward ). These are actively researched now because it is believed that several, possibly most B stars, are actually part of close binary systems with a small “type O subdwarf” ,or white dwarf ( or in some cases neutron star or even black hole!) accounting for mass transfer between the 2 stars which gives rise to the rapid rotation of the B star and formation of a gaseous disc surrounding the star. This is the reason for the emission feature. Close analysis of the emission profile changes over time in the HA region or other regions can yield a solution for orbital parameters of a binary system, thus proving they exist! The peaked nature of the Ha emission is dependent on line of sight from earth as shown in this schematic:
Position ‘A’ viewed from Earth would be looking directly ‘above’ the star where we see only an emission peak. Position ‘B’ is an oblique view where we would see 2 peaks with central dip depending on degree of obliquity but this “dip” gradually increases in depth toward the “C” position where we see the full absorption component (peak pointing down) at the H alpha 6563 angstrom point when we are looking at the star edge on!
I think one of the compelling things about amateur spectroscopy is that this kind of data that I have shown here, despite being obtained with amateur equipment, is still highly sought after by professional researchers. Once these spectra are “validated” by the BeSS administrators then they are considered accurate enough to be used in astrophysical research. Remember that most astronomers do not have daily access to equipment like we do! They have to vie for telescope time with many others and perhaps they will get a day or a few days once every year or more, if they are lucky, on one of the big telescopes either on Earth or in space but this resource that we provide enables researchers to acquire data any time anywhere at will! Spectroscopy or the analysis of light from stars and other objects in space is the way that we have figured out how stars work and evolve over time as well as the large scale structure of the universe. It is also a very viable way that we amateurs, you and me , can still participate and be relevant in new discoveries out there in our universe! For more information on astronomical spectroscopy you can read my primer that I wrote for ‘Reflector” magazine in this post
Thanks for reading!
Haven’t had a chance to report on the last 2 days of the conference, now 3 weeks ago, which was really a ground breaking event all around. I met a lot of great people from literally all over the world! Many were inspired to hopefully get started in this fascinating “subspecialty” of amateur astronomy. For myself, I learned a ton and was able to get started on a couple of research projects with the professional astronomers in attendance. Probably as a direct result of the information presented at this event, I was able to have my first spectrum accepted into the Be star global database (called BeSS) which is a resource used by astronomers worldwide.
Attendees at the recent workshop. I am in the back (arrow) . People came from as far away as Australia and New Zealand!
Francois Cochard, one of the co-owners of Shelyak Instruments discussed the challenge of finding dimmer stars when doing spectroscopy observations.
Dr Katie Devine from the College of Idaho gave a presentation on her focus of interest which is the study of massive star forming regions and spectroscopic observations of these areas in the radio frequencies
My favorite talk was by Drew Chojnowski, graduate student from New Mexico State University ,on the spectroscopy of giant emission binary systems or those with a type B emission star (B star with a surrounding disk of gas) and also containing a small type O star orbiting, called an O “subdwarf”. These are much dimmer than regular type O stars but still have a brightness 10-100 times that of the Sun!
Drew presented spectroscopy data he obtained using the Apogee 3.5m scope and Echelle spectrograph (not far from here!) from another exotic binary star consisting of a Be star and a probable OB subdwarf. Using emission lines in the spectra he was able to resolve the orbital parameters of the binary system!
Olivier Garde, also from Shelyak Instruments in France presented a fascinating talk on how to identify new planetary nebulae with spectroscopy!
Inspired by the fascinating talks at the event, I obtained this spectrum of HD51354 the second night, when the weather was good. It is a magnitude 7.2 Be star with suspected O companion which is not readily detectable with any of the usual absorption or emission lines but apparently it was directly observed in the ultraviolet region. This is just showing the H alpha peak emission which is split because of the orbiting disc component. My future task is to observe Silicon emission a little more to the blue side of this so that the orbital parameters of the binary can be calculated! I was pretty excited that this spectrum was accepted into the BeSS database (see above) because it kind of confirms that you “probably” know what you are doing and can now focus on the science!
And here is my very first entry into the database. Many more to come!
Thanks for reading!