Why are Stars in the constellation Canis Major so massive and luminous?

why are Star in the constellation Canis Major so Massive and luminous? has very bright absolute magnitudes?





while other constellations that are also bathed in Milky way like Auriga, Aquila and Gemini have only a few?|||Many in that direction (that is what is meant when we say 'Canis Major') are in the 'Orion' arm or thereabouts where star formation is going on. In such sites of star-births there is more probability of massive and luminous stars.|||Because the stars in Canis Major happen to be closer to us than the stars in other constellations. For example, Sirius, the brighest star in the sky, appears to be so bright not only due to its size, but also, actually mostly, due to its distance from Earth. Sirius is the seventh closest star to our Earth besides the sun.|||The properties of stars are not related to the arbitrary constellations that we put them in.|||Because Canis Major is a seat for Collinder 121 and the Local Superbubble. Unless you don't study OB Groups and stellar dynamics, you won't be able to answer this question.





Collinder 121 is a 10 million year old dispersing open cluster with a mean distance of 1,800 light-years. It contains a few supergiants - Aludra (B5Iab, 1760 light-years, 66,000 suns), Wezen (F8Ia, 1790 light-years, 50,000 suns), Omicron-2 CMa (B3Iab, 2500 light-years, 110,000 suns), and Omicron-1 CMa (K3Iab, 2000 light-years, 65,000 suns).





Mirzam and Adharaz are runaway stars traversing the Local Superbubble. They are nowhere connected to this region of the sky. However, the bubble itself is a force in the star formation in this region of the sky.





Also, there are a few massive clusters in this region of the sky like the one centered in Tau CMa which a massive cluster about 4,900 light-years away.





Lastly, Canis Major is near the Carina Arm of the Milky Way as seen from our vantage point here on Earth.