l**n
发帖数: 67 | 1 How can people quantify the decelaration of the universei in experiment?
The best way so far is by observing how a standard candle
(objects with known Luminocity) dims as a function of redshift,
usually shown as a Hubble diagram.
How can we find a standard candle?
Type Ia Supernovae(SNe Ia) offer high intrinsic luminosity and
as an individual star it is less affected by the same evolutionary
effect that plagues galaxies. In other words, we want something
well k | i*******n
发帖数: 166 | 2
The intrisic luminosity is a function of the fading time scale.
It is called flux: energy received per unit time per unit area
Luminosity is the energy released per unit time.
This distance is called luminosity distance (to tell apart from
other kinds of distances, such as angular diameter distance). (practically,
distance module which is the difference of the apparent magnitude and
the absolute magnitude is used).
【在 l**n 的大作中提到】
: How can people quantify the decelaration of the universei in experiment?
: The best way so far is by observing how a standard candle
: (objects with known Luminocity) dims as a function of redshift,
: usually shown as a Hubble diagram.
:
: How can we find a standard candle?
: Type Ia Supernovae(SNe Ia) offer high intrinsic luminosity and
: as an individual star it is less affected by the same evolutionary
: effect that plagues galaxies. In other words, we want something
: well k
| c**********g
发帖数: 222 | 3
>>> They measure the flux and the redshift and plot these two parameters. This
diagram is called Hubble-diagram. From this method, they can independently
measure the Hubble constant and the \Omega_m, \Omega_lambda.
【在 i*******n 的大作中提到】
:
: The intrisic luminosity is a function of the fading time scale.
: It is called flux: energy received per unit time per unit area
: Luminosity is the energy released per unit time.
: This distance is called luminosity distance (to tell apart from
: other kinds of distances, such as angular diameter distance). (practically,
: distance module which is the difference of the apparent magnitude and
: the absolute magnitude is used).
:
:
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