Topic 13: Exploring Starlight
Specification
Point Necessary Understanding
13.1 Understand the AU scale and how apparent magnitude relates to the brightness of
stars when viewed from Earth
13.2 Understand the term of absolute magnitude
13.3 Use the distance modulus formula to determine magnitude and distance of a star
13.4 Understand information that can be obtained from a stellar spectrum
13.5 Understand how stars can be classified according to spectral type
13.6 Understand how a star’s colour and spectral type related to surface temperature
13.7 Be able to sketch a simple Hertzsprung-Russel diagram
Understand how a star’s life cycle relates to its position on the Hertzsprung-Russel
13.8
diagram
, Understand the astronomical magnitude scale and how apparent magnitude relates to the brightness of
13.1
stars a viewed from Earth
13.2 Understand the term absolute magnitude
Magnitude is a unitless measuremen
the brightness of an object.
The astronomical magnitude scale
logarithmic.
Astronomers have two different defin
of magnitude:
Apparent Magnitude
Brightness of an object, dependent
object’s intrinsic luminosity, its dist
and the extinction (i.e., light absorpt
scattering) of its light
Absolute Magnitude
[1]
The intrinsic luminosity emitted b
object.
Absolute Magnitude = Apparent Mag
if the star were 10 parsecs aw
,13.1, 2
What is magnitude in relation to stars?
How is magnitude defined?
What is the definition of apparent and absolute magnitude?
How do apparent and absolute magnitude differ?
, 13.3 Use the distance modulus function
Understand the inverse square relationship between distance and
13.9
brightness/intensity
When quantifying the magnitude of a star, it is useful to consider
how the star’s light diminishes in intensity over distance: the
inverse-square law.
When expressing the distance in astronomy, we can use the
distance modulus system to describe distances on a logarithmic
[1]
scale based on the astronomical magnitude system.
𝑚− 𝑀
log 10 ( 𝑑)=1+
5 The distance modulus (µ) is the difference between the appa
magnitude (m) – ideally corrected by interstellar absorption
the absolute magnitude (M) of an astronomical object.
( )
𝑑 Where M is defined as the apparent magnitude of an object when see
𝑚 − 𝑀 =5 log 10 distance of 10 parsecs…
10
The distance modulus function is regularly used to express
distance to other galaxies in the relatively nearby univer
Specification
Point Necessary Understanding
13.1 Understand the AU scale and how apparent magnitude relates to the brightness of
stars when viewed from Earth
13.2 Understand the term of absolute magnitude
13.3 Use the distance modulus formula to determine magnitude and distance of a star
13.4 Understand information that can be obtained from a stellar spectrum
13.5 Understand how stars can be classified according to spectral type
13.6 Understand how a star’s colour and spectral type related to surface temperature
13.7 Be able to sketch a simple Hertzsprung-Russel diagram
Understand how a star’s life cycle relates to its position on the Hertzsprung-Russel
13.8
diagram
, Understand the astronomical magnitude scale and how apparent magnitude relates to the brightness of
13.1
stars a viewed from Earth
13.2 Understand the term absolute magnitude
Magnitude is a unitless measuremen
the brightness of an object.
The astronomical magnitude scale
logarithmic.
Astronomers have two different defin
of magnitude:
Apparent Magnitude
Brightness of an object, dependent
object’s intrinsic luminosity, its dist
and the extinction (i.e., light absorpt
scattering) of its light
Absolute Magnitude
[1]
The intrinsic luminosity emitted b
object.
Absolute Magnitude = Apparent Mag
if the star were 10 parsecs aw
,13.1, 2
What is magnitude in relation to stars?
How is magnitude defined?
What is the definition of apparent and absolute magnitude?
How do apparent and absolute magnitude differ?
, 13.3 Use the distance modulus function
Understand the inverse square relationship between distance and
13.9
brightness/intensity
When quantifying the magnitude of a star, it is useful to consider
how the star’s light diminishes in intensity over distance: the
inverse-square law.
When expressing the distance in astronomy, we can use the
distance modulus system to describe distances on a logarithmic
[1]
scale based on the astronomical magnitude system.
𝑚− 𝑀
log 10 ( 𝑑)=1+
5 The distance modulus (µ) is the difference between the appa
magnitude (m) – ideally corrected by interstellar absorption
the absolute magnitude (M) of an astronomical object.
( )
𝑑 Where M is defined as the apparent magnitude of an object when see
𝑚 − 𝑀 =5 log 10 distance of 10 parsecs…
10
The distance modulus function is regularly used to express
distance to other galaxies in the relatively nearby univer
