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

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Expand view Topic review: APOD: Young Stars and Dusty Nebulae in Taurus (2017 Mar 30)

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

by DavidLeodis » Fri Mar 31, 2017 5:35 pm

neufer wrote:
DavidLeodis wrote:
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 :).

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

by neufer » Fri Mar 31, 2017 3:07 pm

DavidLeodis wrote:
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

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

by DavidLeodis » Fri Mar 31, 2017 1:50 pm

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.

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

by MarkBour » Fri Mar 31, 2017 2:45 am

Ann wrote: . . . 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.
Ann wrote: 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
SmallDrink.JPG (29.49 KiB) Viewed 8806 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 ...

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

by Ann » Thu Mar 30, 2017 11:44 pm

Chris Peterson wrote:
neufer wrote:
Ann wrote:
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

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

by BDanielMayfield » Thu Mar 30, 2017 10:52 pm

Chris Peterson wrote:
neufer wrote:
Ann wrote:
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

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

by ta152h0 » Thu Mar 30, 2017 9:52 pm

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

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

by Fred the Cat » Thu Mar 30, 2017 9:07 pm

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. :clap:

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

by Chris Peterson » Thu Mar 30, 2017 2:17 pm

neufer wrote:
Ann wrote:
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.

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

by starsurfer » Thu Mar 30, 2017 12:36 pm

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.

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

by Ann » Thu Mar 30, 2017 12:06 pm

heehaw wrote: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

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

by heehaw » Thu Mar 30, 2017 11:37 am

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

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

by neufer » Thu Mar 30, 2017 5:08 am

Ann wrote:
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☉

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

by ta152h0 » Thu Mar 30, 2017 5:01 am

wonder if those dark blobs are buckyballsclouds ?

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

by Ann » Thu Mar 30, 2017 4:33 am

Nice picture! :D

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

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

by APOD Robot » Thu Mar 30, 2017 4:09 am

Image 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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