today: formation of spectral lines properties of spectral ... · applications of spectroscopy...
TRANSCRIPT
Today: Formation of Spectral Lines
Properties of Spectral Lines
Applications of Spectroscopy
Astronomy 101 Lecture # 10
Image Credit: Wallace Sargent
Astronomy 101 Lecture # 10
Image Credit: Magrini et al. 2005
Astronomy 101 Lecture # 10
σ
Astronomy 101 Lecture #10
e
Photon – Electron “Collisions”
σ
Photon – Electron “Collisions”
ct
e
Iλ()
d =−n
ds
0
Iλ(0)
Astronomy 101 Lecture #10
n,λ, j
λ
Radiative Transfer Equation with Absorption + Emission
d I
d
=I−S
S=j
n
Astronomy 101 Lecture #10
I0= I
e−S
1−e−
Solution to the Radiative Transfer Equation
Proportion of H atoms in the first excited state as a function of temperature
H is ionized
H is in its ground state
The dependence of spectral line strength on temperature
Credit & Copyright: C&O, figure 8.11
Spectral Types of Stars
Zeeman splitting near sunspots
●Image Credit: odin.physastro.mnsu.edu
Astronomy 101 Lecture # 10
2D spectrum of a spiral galaxy
●Image Credit: Nicole Vogt NMSU
Astronomy 101 Lecture # 10
SuperMassive Black Holes
Astronomy 101 Lecture # 10
Image scale: 1”=17 pc
MBH = 2x108Msun
Astronomy 101 Lecture # 10
V = 400 km/sd = 8 pcM > 1.5x109M
sun
Stellar rotation in the vicinity of a Black Hole
[N II] λ6583
λ
NGC 4258 is a spiral galaxy with a central black hole of mass:
●Image courtesy of ●NRAO/AUI and ●L Greenhill (CfA)
M≃5×107 Msun
Narrow and Broad Emission Lines
Astronomy 101 Lecture # 10
Image scale: 1”=17 pc
MBH = 2x108Msun
Image Credit: Donald Osterbrock (Lick Observatory)
The spectrum of a broadline radio galaxy PKS 234901. The forbidden lines are narrow, while the Balmer recombination lines are extremely broad.
AGN Unification Theory
Astronomy 101 Lecture # 10
Black Hole Accretion Disk
●Image credit: www.jca.umbc.edu
Simulated Spectrum of line Fe K (n=2 to n=1 transition)
Image credit: NASA
Astronomy 101 Lecture # 10
Astronomy 101 Lecture # 10
The average Xray spectrum of active galaxies in the Xray background with the continuum subtracted.Image Credit: Max Planck Institute for Extraterrestrial Physics
XRay spectrum of Serpens X1Image Credit: Sudip Bhattacharyya and Tod Strohmayer
Equivalent Width
Astronomy 101 Lecture # 10
Lα Forest
Forbidden Lines
Astronomy 101 Lecture # 10