APOD: Young Stars and Dusty Nebulae in Taurus (2017 Mar 30)

[APOD Robot]

Young Stars and Dusty Nebulae in Taurus

Explanation: This complex of dusty nebulae lingers along the edge of the Taurus molecular cloud, a mere 450 light-years distant. Stars are forming on the cosmic scene. Composed from almost 40 hours of image data, the 2 degree wide telescopic field of view includes some youthful T-Tauri class stars embedded in the remnants of their natal clouds at the right. Millions of years old and still going through stellar adolescence, the stars are variable in brightness and in the late phases of their gravitational collapse. Their core temperatures will rise to sustain nuclear fusion as they grow into stable, low mass, main sequence stars, a stage of stellar evolution achieved by our middle-aged Sun about 4.5 billion years ago. Another youthful variable star, V1023 Tauri, can be spotted on the left. Within its yellowish dust cloud, it lies next to the striking blue reflection nebula Cederblad 30, also known as LBN 782. Just above the bright bluish reflection nebula is dusty dark nebula Barnard 7.

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[Ann]

Nice picture!

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called a medium-mass star instead.

Ann

[ta152h0]

wonder if those dark blobs are buckyballsclouds ?

[neufer]

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called medium-mass stars instead.

• The heaviest stars have a mass of ~150 M_☉
  The lightest 'stars' have a mass of ~1/80 M_☉
  
  So the geometric mean is ~1.37 M_☉

[heehaw]

I'm afraid that the picture reveals that we live in a FILTHY universe. Get out your brooms!

[Ann]

I'm afraid that the picture reveals that we live in a FILTHY universe. Get out your brooms!

Click to play embedded YouTube video.

Ann

[starsurfer]

This is a lovely region of the Taurus Molecular Ring. Also fun for galaxy hunting, the galaxy in the bottom right corner is IC 359.

[Chris Peterson]

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called medium-mass stars instead.

• The heaviest stars have a mass of ~150 M_☉
  The lightest 'stars' have a mass of ~1/80 M_☉
  
  So the geometric mean is ~1.37 M_☉

Of course, in forming these definitions (and they are somewhat arbitrary) we might reasonably consider the mass distribution, as well, not just the extreme values. Stellar masses follow some sort of power law, which might suggest natural boundaries for "low", "medium", and "high" mass stars.

[Fred the Cat]

Lloyd whatever you did to create today's image please keep up the great work. The image has a depth character that many other molecular cloud and nebula photographs seem to lack. This cosmic scene is quite striking.

[ta152h0]

this week it is cloudy all over. Supposed to clear up by Sunday so I hope this sky is still there then.

[BDanielMayfield]

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called medium-mass stars instead.

• The heaviest stars have a mass of ~150 M_☉
  The lightest 'stars' have a mass of ~1/80 M_☉
  
  So the geometric mean is ~1.37 M_☉

Of course, in forming these definitions (and they are somewhat arbitrary) we might reasonably consider the mass distribution, as well, not just the extreme values. Stellar masses follow some sort of power law, which might suggest natural boundaries for "low", "medium", and "high" mass stars.

A natural boundary on the low end might be the "knee" in the H-R main sequence strip. Stars below this bend are truely dwarf, or small in comparison to the Sun.

Calling main sequence stars like the sun (and even more massive stars) dwarfs is misleading. Why hold on to misleading conventions?

Bruce

[Ann]

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called medium-mass stars instead.

• The heaviest stars have a mass of ~150 M_☉
  The lightest 'stars' have a mass of ~1/80 M_☉
  
  So the geometric mean is ~1.37 M_☉

Of course, in forming these definitions (and they are somewhat arbitrary) we might reasonably consider the mass distribution, as well, not just the extreme values. Stellar masses follow some sort of power law, which might suggest natural boundaries for "low", "medium", and "high" mass stars.

Wikipedia wrote:
The IMF of stars more massive than our sun was first quantified by Edwin Salpeter in 1955.[4] His work favoured an exponent of α =2.35. This form of the IMF is called the Salpeter function or a Salpeter IMF. It shows that the number of stars in each mass range decreases rapidly with increasing mass.

That's all the more reason not to lump solar-mass stars together with small red dwarfs. (And yes, Bruce, the small red dwarfs are dwarfs!)

By the way, I agree with starsurfer and Fred that today's APOD is a great picture!

Ann

[MarkBour]

. . . By the way, I agree with starsurfer and Fred that today's APOD is a great picture!

I agree, this is a very beautiful skyscape; a composition that makes me feel calm, and at peace.

In my opinion, we should be careful how we use the term "low-mass stars". Most stars in our galaxy, and probably in the entire universe, are much less massive than the Sun. Small stars like Proxima Centauri are far more common than solar-mass stars like the Sun. The tiny stars like Proxima Centauri are the real low-mass stars. The Sun, which belongs to the top 90-95th echelon when it comes to mass of stars in the universe, should be called medium-mass stars instead.
Ann

Here, I'll play Devil's advocate. While your point is well-taken, perhaps there are stronger criteria for delineating the groups of stars (stronger than just dividing along the mean or geometric mean, etc.) Or at least, in this APOD, the emphasis is on one such criterion, and so the adjective "low-mass" in regard to that criterion would be appropriate and even instructive? Looking on Wikipedia, I see that these T Tauri stars are small enough to progress through the Hayashi contraction sequence, and that is the main characteristic they are presenting to us here.

https://en.wikipedia.org/wiki/T_Tauri_star
T Tauri stars are pre-main-sequence stars in the process of contracting to the main sequence along the Hayashi track, a luminosity-temperature relationship obeyed by infant stars of less than 3 solar masses (M☉) in the pre-main-sequence phase of stellar evolution.

SmallDrink.JPG (29.49 KiB) Viewed 9639 times

It further goes on to divide out Herbig Ae/Be-type stars, which are pre-main-sequence stars of (2–8 solar masses), and then more massive (>8 Solar mass) stars which are not observed in their pre-main-sequence stages.

So, that makes for a nice "small, medium, large" division.

Okay, I'm done. Excuse me, while I go have a small drink ...

[DavidLeodis]

Assuming that it has one I am wondering what is the name of the bowling pin shaped dark object and its area to the right:?:

There is a nice spiral galaxy in the bottom right corner.

[neufer]

Assuming that it has one I am wondering what is the name of the bowling pin shaped dark object and its area to the right:?:

• Bowling pin 209: B209

[DavidLeodis]

Assuming that it has one I am wondering what is the name of the bowling pin shaped dark object and its area to the right:?:

• Bowling pin 209: B209

Thanks for your help neufer .