Starship Asterisk*

starsurfer wrote:

Ann wrote:Ah. I see your (dolphin) point.

Well, I think stars often lose mass asymmetrically, so why not? Fine round bubble around Antares anyone?

Ann

I think in some areas, asymmetries arise due to the bubble expanding into an inhomogeneous interstellar medium?

Ann wrote:Ah. I see your (dolphin) point.

Well, I think stars often lose mass asymmetrically, so why not? Fine round bubble around Antares anyone?

Ann

Ann wrote:

neufer wrote:

https://en.wikipedia.org/wiki/Omicron1_Canis_Majoris wrote:

[b][color=#0000FF][size=120]ο[sup]1[/sup] CMa appears to be interacting with the nebula around EZ CMa[/size] [size=85]This image was created using the POSS-II/UKSTU data of the Digitized Sky Survey[/size][/color][/b]

---

<<Omicron1 Canis Majoris (ο¹ CMa, ο¹ Canis Majoris) is a variable star in the constellation of Canis Major. Though only separated by 2 degrees from the blue supergiant ο² Canis Majoris, the two appear to be unrelated. The star itself is ae K-type orange supergiant of spectral type K2.5 Iab and is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. A cool star, its surface temperature is around 3,900 K. Around 8 times as massive as the Sun with around 280 times its diameter, it shines with 16,000 times its luminosity. Thought to be around 18 million years old, ο¹ Canis Majoris is undergoing nuclear fusion of helium in its core to generate energy and will one day explode as a type II supernova.

Well, probably. Since its mass is about 8 solar masses today, when it has evolved into a red supergiant and undoubtedly lost a lot of mass through its stellar wind already, it must have started out with more than 8 solar masses, and its core has evolved accordingly. (It is, after all, the state of the core that determines if a massive star will go supernova.) But stars with the initial mass of 8 solar masses may not go supernova. Not even 10 solar masses necessarily seal the supernova fate for a star.

neufer wrote:

https://en.wikipedia.org/wiki/Omicron1_Canis_Majoris wrote:
<<Omicron1 Canis Majoris (ο¹ CMa, ο¹ Canis Majoris) is a variable star in the constellation of Canis Major. Though only separated by 2 degrees from the blue supergiant ο² Canis Majoris, the two appear to be unrelated. The star itself is ae K-type orange supergiant of spectral type K2.5 Iab and is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. A cool star, its surface temperature is around 3,900 K. Around 8 times as massive as the Sun with around 280 times its diameter, it shines with 16,000 times its luminosity. Thought to be around 18 million years old, ο¹ Canis Majoris is undergoing nuclear fusion of helium in its core to generate energy and will one day explode as a type II supernova.

Nancy Atkinson wrote:

White dwarfs are strange stars, but researchers recently discovered two of the strangest yet. However, these two oddballs are a missing link of sorts, between massive stars that end their lives as supernovae and small to medium sized stars that become white dwarfs. Somehow, these two once-massive stars avoided the core collapse of a supernova, and are the only two white dwarfs known to have oxygen-rich atmospheres. These so-called massive white dwarfs have been predicted, but never before observed.
...
Theoretical models predicted that if stars around 7 – 10 times the mass of our own Sun don’t end their lives as supernovae, the other option is that they will consume all of their hydrogen, helium and carbon, and end their lives as white dwarfs with very oxygen-rich cores.

Boomer12k wrote:
Reminded me of a Dolphin's head... Really nice...

https://en.wikipedia.org/wiki/Omicron2_Canis_Majoris wrote:

[size=150]ο² & ο[sup]1[/sup] CMa mark the centre of the[/size] Great Dog's body on Bayer's 1603 Uranometria.

---

<<Omicron2 Canis Majoris (ο² CMa, ο² Canis Majoris) is one of the brighter members of the constellation Canis Major. The distance to this star is roughly 2,800 light years (800 parsecs), with a 34% margin of error. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.

Omicron2 Canis Majoris is one of the most luminous stars known, as it radiates about 220,000 times as much luminosity as the Sun from its outer envelope at a temperature of 15,500 K. At this heat, the star is glowing with the blue-white hue of a B-type star. This star is classified as an Alpha Cygni-type variable star that undergoes periodic non-radial pulsations, which cause its brightness to cycle from magnitude +2.93 to +3.08 over a 24.44 day interval. It is losing mass from its stellar wind at the rate of around 2 × 10⁻⁹ times the mass of the Sun per year.

This is a massive supergiant star with a stellar classification of B3 Ia, indicating that, at the age of around 7 million years, it has exhausted the supply of hydrogen at its core and is now undergoing nuclear fusion of helium to generate energy. It has about 21 times the mass of the Sun and 65 times the Sun's radius. In all likelihood, it will end its life as a Type II supernova.

While this star lies in the field of view of the open cluster named Collinder 121, it is unlikely to be a member. In fact, its optical neighbor, the orange supergiant ο¹ Canis Majoris has a much higher likelihood of 23.1% based upon its proper motion being a closer match to the motion of the cluster.>>

https://en.wikipedia.org/wiki/Omicron1_Canis_Majoris wrote:
<<Omicron1 Canis Majoris (ο¹ CMa, ο¹ Canis Majoris) is a variable star in the constellation of Canis Major. Though only separated by 2 degrees from the blue supergiant ο² Canis Majoris, the two appear to be unrelated. The star itself is ae K-type orange supergiant of spectral type K2.5 Iab and is an irregular variable star, varying between apparent magnitudes 3.78 and 3.99. A cool star, its surface temperature is around 3,900 K. Around 8 times as massive as the Sun with around 280 times its diameter, it shines with 16,000 times its luminosity. Thought to be around 18 million years old, ο¹ Canis Majoris is undergoing nuclear fusion of helium in its core to generate energy and will one day explode as a type II supernova.>>

https://en.wikipedia.org/wiki/EZ_Canis_Majoris wrote:

[b][color=#0000FF][size=120]ο[sup]1[/sup] CMa appears to be interacting with the nebula around EZ CMa[/size] [size=85]This image was created using the POSS-II/UKSTU data of the Digitized Sky Survey[/size][/color][/b]

---

<<EZ Canis Majoris (EZ CMa) is a Wolf-Rayet star in the constellation of Canis Major. It is one of the ten brightest Wolf-Rayet stars. EZ CMa has an apparent visual magnitude which varies between 6.71 and 6.95 over a period of 3.766 days, along with changes in the spectrum. It has been proposed that it could be a binary star, with a neutron star as companion that would complete an orbit around the Wolf-Rayet with that period, being it the cause of those variations. The General Catalogue of Variable Stars lists it as a possible cataclysmic variable on this basis. However it seems more likely that companion does not exist and spectral variations are caused by activity on the star's surface.

The spectral type of WN4 indicates an extremely hot star, and this leads to a very high luminosity, mostly emitted as ultraviolet radiation. The spectrum shows a star entirely devoid of hydrogen at the surface. EZ CMa is surrounded by a faint bubble nebula, a small HII region blown by stellar winds up to 1,700 km/s and ionised by the intense UV radiation. This is catalogued as Sharpless 308 or just S308. It is likely to be a member of the very scattered open cluster Collinder 121, found around the orange supergiant ο¹ CMa.>>

dlw wrote:

Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution.

Would that imply that the irregularities in the bubble such as the hedgehog nose in the upper left indicate something about the distribution of slower moving material in that area?

hedgehog-pictures-20.jpg

Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution.

Saeed Khan wrote:Quote: "Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution."

All of them? All Wolf-Rayet stars in the Universe?