Kurt loves a bit of stellar spectroscopy and encouraged by his friend and sometimes astronomical collaborator, Professor GP, he captured the spectral data for the amazing Carbon Star - La Superba, using the JPO's 127mm. apo-refractor and a spectrometer designed and 3d printed by our on-site engineer Jolene McSquint -Fleming in the observatory's clean room'. - Joel Cairo CEO of the Jodrell Plank Observatory.
For an absolutely fantastic image of this 'very red star' follow the link.
https://apod.nasa.gov/apod/ap081218.html
"For an explanation of this 'cool', in every sense of the word, star, I asked the JPO's visiting physicist, G.P.T. Chat Phd, to describe its general features and spectral details using a comparative methodology" - Kurt Thrust current Director of the Jodrell Plank Observatory.
La Superba and Stellar Evolution: A Comparative Analysis on the Hertzsprung-Russell Diagram
Introduction
Stars are the fundamental building blocks of galaxies, and their life cycles reflect the underlying physics that governs the universe. Among the many types of stars observed, carbon stars represent a fascinating late stage in stellar evolution. One of the most prominent and well-studied carbon stars is La Superba, also known as Y Canum Venaticorum. This essay explores La Superba's characteristics in detail and places it in context with several other well-known stars using the Hertzsprung-Russell (H-R) diagram.
La Superba: An Overview
La Superba is located in the constellation Canes Venatici,
visible in the northern hemisphere, especially during spring. Its coordinates
(J2000 epoch) are:
- Right Ascension: 12h 45m 07.83s
- Declination: +45° 26′ 24.9″
It lies approximately 710 light-years from Earth and is classified as a
carbon-rich red giant — one of the brightest of its kind visible to the naked
eye. As a semi-regular variable star, its apparent magnitude varies from +4.9
to +6.3.
La Superba's physical parameters make it particularly interesting:
- Temperature: ~2,750 K
- Luminosity: ~9,000 L☉ (9000 x Sun's luminosity)
- Radius: ~400–500 R☉ (400 to 500 x Sun's radius)
It is a C-type (carbon) star, having undergone internal helium burning via the
triple-alpha process, which produces carbon that is brought to the surface
through convective dredge-up. This enrichment gives rise to a spectrum rich in
carbon molecules, including C₂ (Swan bands), CN, and CH. These features result
in deep molecular absorption bands, giving the star a very red appearance and
making it a textbook example of a cool, evolved star on the Asymptotic Giant
Branch (AGB).
Spectral Features
La Superba’s spectral type is typically classified as C6,2e in the revised carbon star classification system. It exhibits strong molecular absorption features and sometimes weak emission lines like H-alpha during pulsation events. The absence of oxygen-bearing molecules like TiO, common in M-type giants, highlights the dominance of carbon chemistry in its atmosphere.
Position on the H-R Diagram
The Hertzsprung-Russell diagram plots stars by their
luminosity (vertical axis) and surface temperature (horizontal axis, decreasing
rightward). La Superba occupies the upper-right portion of the H-R diagram — a
region dominated by cool, highly luminous red giants and supergiants.
To provide comparative context, several other prominent stars are also plotted:
- The Sun – A G-type main sequence star with a surface temperature of 5,778 K
and luminosity of 1 L☉.
- Deneb – A luminous blue-white supergiant (~8,500 K, 196,000 L☉).
- Sirius – A bright A-type main-sequence star (~9,940 K, 25.4 L☉).
- Arcturus – An orange giant (~4,286 K, 170 L☉).
- Capella – A system of G-type giants (~5,700 K, 78.7 L☉).
- Betelgeuse – A red supergiant (~3,500 K, 126,000 L☉).
- Castor – An A-type star (~10,100 K, 52.4 L☉).
- Pollux – An orange giant (~4,865 K, 43 L☉).
- Vega – A well-known A-type main-sequence star (~9,602 K, 40.1 L☉).
These stars cover a range of spectral types and evolutionary stages, allowing
us to place La Superba within the broader context of stellar evolution.
H-R Diagram
Conclusion
La Superba serves as a striking example of late stellar evolution and highlights the diversity of stars when viewed through the lens of temperature and luminosity. Its placement on the H-R diagram underscores the dramatic changes stars undergo during their lifespans. Comparing La Superba with other well-known stars reveals the full spectrum of stellar development — from main-sequence hydrogen burners to evolved giants and future white dwarfs". - G.P.T. Chat Phd visiting physicist at the Jodrell Plank Observatory
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