physics 320: astronomy and astrophysics – lecture xi
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Physics 320: Astronomy and Astrophysics – Lecture XI. Carsten Denker Physics Department Center for Solar–Terrestrial Research. Lunar Eclipse November 8 th ,2003. Eclipsed Moonlight from Connelly's Springs, NC by David Cortner. Problem 11.1. Problem 11.2. Problem 11.8. - PowerPoint PPT PresentationTRANSCRIPT
NJIT
Physics 320: Astronomy and Astrophysics – Lecture XI
Carsten Denker
Physics DepartmentCenter for Solar–Terrestrial Research
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Lunar Eclipse November 8th,2003
Eclipsed Moonlight from Connelly's Springs, NC by David Cortner.
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Problem 11.1
2 4
1/ 4 1/ 2 1/ 21/ 4
4
10.71
0.88
5640 K
57
0.979
7 7
K9
00. 7
e
i i
i
i
L R T
RT L
T L R
T
T
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Problem 11.2
2 49 14
2 2
14
310
10
4(a) 4.26 10 kg/s 6.75 10 M /yr
(b) 3 10 M /yr (see Example 11.1)
3 10 M(c) The life time of the Sun is about 10 years.
10 yr
edM L R T
dt c cdM
dt
M
t
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Problem 11.8
0, 0,0,0 0
1 1
2 2
1 2
(Eqn.: 9.13)
1 (with 2 / 3)
: 102.6 km (you can see deeper into the Sun)
: 88.9 km
= 13.7 km
d
d ds
d ds d
d
d
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Physical Processes in the Solar System
A Brief Survey Stellar Evolution Planetary Systems
Tidal ForcesThe Physics of
Atmospheres
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Protoplanetary Disks
J. Bally (U. Colorado), H. Throop (SwRI), C.R. O'Dell (Vanderbilt U.), NASA
November 12th, 2003NJIT Center for Solar-Terrestrial Research
A Brief Survey
Terrestrial Jovian
Basic form rocky gas/liquid/ice
Mean orbital distance [AU]
0.39 – 1.52 5.2 – 30.1
Mean surface temperature [K]
200 – 750 75 – 170
Mass [M] 0.055 – 1.0 14.5 – 318
Equatorial Radius [R] 0.38 – 1.0 3.88 – 11.2
Mean density [g cm-3] 3.95 – 5.52 0.69 – 1.64
Sidereal rotation period (equator)
23.9 h – 243 d 9.8 h – 19.2 h
Number of known moons
0 – 2 8 – 20
Ring systems no yes
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Relative Sizes of Planets
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Titius–Bode Rule
Planet Titius–Bode Distance [AU]
Actual Mean Distance [AU]
Mercury (4 + 3 0 ) / 10 = 0.4 0.39
Venus (4 + 3 20) / 10 = 0.7 0.72
Earth (4 + 3 21) / 10 = 1.0 1.00
Mars (4 + 3 22) / 10 = 1.6 1.52
Ceres (4 + 3 23) / 10 = 2.8 2.77
Jupiter (4 + 3 24) / 10 = 5.2 5.20
Saturn (4 + 3 25) / 10 = 10.0 9.54
Uranus (4 + 3 26) / 10 = 19.6 19.19
Neptune (4 + 3 27) / 10 = 38.8 30.06
Pluto (4 + 3 28) / 10 = 77.2 39.53
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Solar System Inventory
Sun Planets Moons Asteroid belt (2 – 3.5 AU) Comets
Kuiper belt (30 AU) Oort cloud (3000 – 100,000 AU)
Meteoroids, meteor, meteorite, and meteor shower asteroid and comet debris
Zodiacal light
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Thousands of stars, several constellations, a planet and a comet all graced the western horizon over Ujue, Spain just after sunset on April 4th, 1997. Because the picture was taken with a fisheye lens, much of the whole night sky is visible. Comet Hale-Bopp, with both tails blazing, appears right of center. The brightest star is Sirius near the edge, well to the left of the constellation Orion. The red star above the belt of Orion is Betelgeuse, while the red star near the center is Aldebaran, to the left of the bright Pleiades star cluster. Many other interesting astronomical objects are visible, e.g., the zodiacal light, which is the diffuse triangular glow in the center.
Zodiacal Light
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Origin of the Solar System
Gravitational collapse of the original solar nebula
Formation of accretion disk around proto–sun Planetesimals (terrestrial planets) and
additional presence of ice (jovian planets) More massive planets accumulate extensive
primordial H/He atmospheres Jovian planets have local accretion disks Capturing of moons Cometary nuclei either catapulted into Oort
cloud or completely ejected from solar system
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Tidal Forces
12 3
2mm m
dFMm MmF G dF dr G dr
r dr r
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Tidal Forces (cont.)
, ,2
, ,2 2
Center : 0
Point : cos sin
C x C y
P x P y
GMmC F F
rGMm GMm
P F Fs s
2 2 2
cos 1 ˆ ˆsinP C
GMmF F F GMm i j
s r s
2 22
2
2 2
cos sin
21 cos
neglect terms / 1
s r R R
Rr
r
R r
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Tidal Forces (cont.)
2
2
2 1cos and 1 1
1
2 ˆcos 1 cos 1
2 ˆsin 1 cos
Rx x x
r x
GMm RF i
r r
GMm Rj
r r
3
sincos 1 and sin
ˆ ˆ2cos sin
R
rGMmR
F i jr
Earth’s rotation period is lengthening at a rate of 0.0016 s/century and the Moon is drifting away from Earth by 3 to 4 cm/year.
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Physics of Atmospheres2 4
eff (Stefan-Boltzmann equation4 )L R T
Under equilibrium conditions, a planet’s total energy content must remain constant. Therefore, all of the energy absorbed by the planet must be reemitted. If not, the planet’s temperature would change with time.
1/ 4 ( : albe1
2do)p
RT T a a
D
0.3 255 K 19
Greenhouse Effect!
Ca T
November 12th, 2003NJIT Center for Solar-Terrestrial Research
ExosphereThe region in an atmosphere where the mean free path of the particles become long enough for them to travel without appreciable collisions is referred to as exosphere.
23/ 2
/ 2 24
(Maxwell Boltzmann distribution)
2mv kT
v
mn dv n e v dv
kT
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Exosphere (cont.)
rms esc rms esc
1 3 2 with and
6
1
54p
escp
kT GMv v v v
m rGM m
TkR
esc 2
Moon
esc 2
255 K
(N ) 3900 K
274 K
(N ) 180 K
T
T
T
T
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Atmospheric Dissipation and Mixing
2
(photodissociation)
H H H
Coriolis
(Coriolis for
2
ce)rF m v
Gravitational or chemical differentiation
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Homework Class Project
Continue improving the PPT presentation. Use the abstract from the previous assignment
as a starting point for a PowerPoint presentation.
The PPT presentation should have between 5 and 10 slides.
Bring a print-out of the draft version to the next class as a discussion template for group work
Homework is due Wednesday November 19th, 2003 at the beginning of the lecture!
Exhibition name competition!
November 12th, 2003NJIT Center for Solar-Terrestrial Research
Homework
Homework is due Wednesday November 19th, 2003 at the beginning of the lecture!
Homework assignment: Problems 18.1, 18.5, and 18.7!
Late homework receives only half the credit!
The homework is group homework!Homework should be handed in as a
text document!