I What does L star mean in the Schechter function?

AI Thread Summary
The L star (L*) in the Schechter function represents the characteristic galaxy luminosity where the distribution of galaxy brightness transitions from a power-law increase at the faint end to a rapid exponential decline at the bright end. This function is used to empirically fit the brightness distributions of galaxies, indicating that while many galaxies are dim, those with luminosities around L* are significantly less common. L* typically corresponds to the luminosity of large galaxies like the Milky Way or Andromeda. The rarity of galaxies brighter than L* emphasizes the unique nature of such massive galaxies. Understanding L* is crucial for studying galaxy formation and distribution in the universe.
I_laff
Messages
41
Reaction score
2
I'm trying to understand the Schechter function, I read on Wikipedia that the L star term in the function is the 'characteristic galaxy luminosity where the power-law form of the function cuts off'. What does this mean exactly?
 
Astronomy news on Phys.org
It's just an empirical fitting function to the brightness distributions. It's found empirically that the number of galaxies in a certain brightness range increases as a power law at the faint end, but drops off more quickly (exponentially) at the bright end. The L* luminosity is where the function transitions from one behavior to the other. These slides have a nice description.
 
  • Like
Likes I_laff
Thanks for the explanation [emoji846]
 
L* is the luminosity of a giant galaxy like the Milky Way or Andromeda. Such galaxies are rare, and galaxies much brighter are even rarer.

See this article on super spiral galaxies for more.
 

Thread 'How feasible is home radio astronomy?'

Is a homemade radio telescope realistic? There seems to be a confluence of multiple technologies that makes the situation better than when I was a wee lad: software-defined radio (SDR), the easy availability of satellite dishes, surveillance drives, and fast CPUs. Let's take a step back - it is trivial to see the sun in radio. An old analog TV, a set of "rabbit ears" antenna, and you're good to go. Point the antenna at the sun (i.e. the ears are perpendicular to it) and there is...
View full post »

Thread 'Our Beautiful Universe - Photos and Videos'

This thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it less beautiful to me (n.b. the posts must of course comply with the PF guidelines, i.e. regarding science, only mainstream science is allowed, fringe/pseudoscience is not allowed). n.b. I start this...
View full post »

Similar threads

B How to calculate a star's luminosity/radius
Replies
15
Views
10K
I Relationship between star radius and luminosity
Replies
5
Views
5K
Does Increasing Luminosity Affect the Percentage of Dark Matter in a Galaxy?
Replies
4
Views
1K
I Understanding diagrams of the late stages of stellar evolution
Replies
1
Views
2K
I Calculating planet's radius using a star's luminosity
Replies
32
Views
7K
Understanding the Luminosity of Radiative Stars
2
Replies
75
Views
9K
I Red-Shifting vs. Luminosity Question
Replies
3
Views
2K
I The Explanation for the Mass-Luminosity Relation
Replies
10
Views
3K
Globular cluster luminosity function
Replies
3
Views
2K
I Nuclear reactions in the Sun and other topics on stars
Replies
49
Views
5K

Hot Threads

Recent Insights

Back
Top