Ast

rono

my

100

Tue

sday

, Thu

rsda

y 2:

30 -

3:45

pm

Tom

Bur

bine

tbur

bine

@m

thol

yoke

.edu

ww

w.x

anga

.com

/ast

rono

my1

00

OW

L as

sign

men

t (D

ue T

oday

)

•Th

ere

is b

e an

OW

Las

sign

men

t due

on

Tues

day

Apr

il 5

at 1

1:59

pm

.•

Ther

e ar

e 15

que

stio

ns a

nd a

per

fect

scor

e w

ill

give

you

2 h

omew

ork

poin

ts.

Exam

•40

Que

stio

ns•

Cha

pter

s 15,

16,

17,

and

18

•So

me

of th

e qu

estio

ns a

re ta

ken

stra

ight

from

O

WL

ques

tions

Oth

er R

oom

•A

pril

7th

Goe

ssm

ann

0020

2:

30-3

:45

PM

Last

Nam

es b

egin

ning

with

H, I

, J, a

nd K

Thin

gs y

ou sh

ould

kno

w•

Laye

rs o

f the

Sun

•H

ydro

gen

Fusi

on•

Her

tzsp

rung

-Rus

sell

Dia

gram

•St

ella

r Cla

ssifi

catio

ns•

Life

Cyc

le o

f the

Sun

•H

eliu

m F

usio

n•

CN

O c

ycle

•W

hat h

appe

ns to

star

s as t

hey

“die

”

Rev

iew

Ses

sion

•W

edne

sday

-Rev

iew

Ses

sion

–H

asbr

ouck

134

from

7-8

pm

–I w

ill b

e th

ere

at 6

pm

if y

ou w

ant t

o ta

lk to

me

in a

m

uch

smal

ler g

roup

PRS

Que

stio

ns

PRS

ques

tion

#1

•W

hat i

s app

roxi

mat

ely

the

tem

pera

ture

of t

he

plas

ma

in a

suns

pot?

–A

) 2,0

00 K

–B

) 4,0

00 K

–C

) 6,0

00 K

–D

) 8,0

00 K

–E)

10,

000

K

PRS

ques

tion

#1

•W

hat i

s app

roxi

mat

ely

the

tem

pera

ture

of t

he

plas

ma

in a

suns

pot?

–A

) 2,0

00 K

–B

) 4,0

00 K

–C

) 6,0

00 K

–D

) 8,0

00 K

–E)

10,

000

K

PRS

Que

stio

n #2

•W

hich

of t

hese

spec

tral t

ypes

hav

e th

e st

rong

est

hydr

ogen

em

issi

on li

nes i

n th

eir s

pect

ra?

–A

) O–

B) B

–C

) A–

D) F

–E)

G

PRS

Que

stio

n #2

•W

hich

of t

hese

spec

tral t

ypes

hav

e th

e st

rong

est

hydr

ogen

em

issi

on li

nes i

n th

eir s

pect

ra?

–A

) O–

B) B

–C

) A–

D) F

–E)

G

“Dea

ths”

of S

tars

•W

hite

Dw

arfs

•N

eutro

n St

ars

•B

lack

Hol

es

Whi

te D

war

fs

•W

hite

Dw

arfs

is th

e co

re le

ft ov

er w

hen

a st

ar c

an

no lo

nger

und

ergo

fusi

on•

Ver

y de

nse

–So

me

have

den

sitie

s of 3

mill

ion

gram

s per

cub

ic

cent

imet

er–

A te

aspo

on o

f a w

hite

dw

arf w

ould

wei

gh a

s muc

h as

an

ele

phan

t

Whi

te D

war

fs

•So

me

whi

te d

war

fs h

ave

the

sam

e m

ass a

s the

Su

n bu

t slig

htly

big

ger t

han

the

Earth

•20

0,00

0 tim

es a

s den

se a

s the

ear

th

Whi

te D

war

fs

•C

olla

psin

g du

e to

gra

vity

•Th

e co

llaps

e is

stop

ped

by e

lect

ron

dege

nera

cy

pres

sure

Elec

tron

Deg

ener

acy

Pres

sure

•N

o tw

o el

ectro

ns c

an o

ccup

y th

e sa

me

quan

tum

st

ate

Elec

tron

Deg

ener

acy

Pres

sure

•A

s ele

ctro

ns a

re m

oved

clo

ser t

oget

her

•Th

eir m

omen

tum

(vel

ocity

) inc

reas

es•

Due

to H

eise

nber

g U

ncer

tain

ty P

rinci

ple

So W

hat D

oes T

his M

ean

•El

ectro

n D

egen

erac

y Pr

essu

re b

alan

ces t

he

grav

itatio

nal f

orce

due

to g

ravi

ty in

whi

te d

war

fs

One

Inte

rest

ing

Thin

g

•M

ore

mas

sive

whi

te d

war

fs a

re sm

alle

r

Whi

te D

war

f Lim

it

•Th

e m

ass o

f a W

hite

Dw

arf c

an n

ot e

xcee

d ap

prox

imat

ely

1.4

Sola

r Mas

ses

•C

alle

d th

e C

hand

rase

khar

Lim

it•

Elec

trons

wou

ld h

ave

velo

citie

s gre

ater

than

the

spee

d of

ligh

t

The

Sun

•W

ill e

nd u

p as

a W

hite

Dw

arf

Neu

tron

Star

•N

eutro

n st

ars a

re u

sual

ly 1

0 ki

lom

eter

s acr

oos

•B

ut m

ore

mas

sive

than

the

Sun

•M

ade

alm

ost e

ntire

ly o

f neu

trons

•El

ectro

ns a

nd p

roto

ns h

ave

fuse

d to

geth

er

How

do

you

mak

e a

neut

ron

star

?

•R

emna

nt o

f a S

uper

nova

How

do

you

get a

Sup

erno

va?

•A

hig

h-m

ass s

tar k

eeps

on

fusi

ng e

lem

ents

into

on

es w

ith la

rger

ato

mic

mas

ses

•Is

now

a R

ed S

uper

gian

t•

Ener

gy k

eeps

on

bein

g re

leas

ed si

nce

the

mas

s of

the

new

nuc

leus

is le

ss th

an th

e or

igin

al o

nes

This

stop

s with

Iron

•Fu

sion

of I

ron

with

ano

ther

ele

men

t doe

s not

re

leas

e en

ergy

•Fi

ssio

n of

Iron

with

ano

ther

ele

men

t doe

s not

re

leas

e en

ergy

•So

you

kee

p on

mak

ing

Iron

Initi

ally

•G

ravi

ty k

eeps

on

pulli

ng th

e co

re to

geth

er•

The

core

kee

ps o

n sh

rinki

ng•

Elec

tron

dege

nera

cy k

eeps

the

core

toge

ther

for

awhi

le

Then

•Th

e iro

n co

re b

ecom

es to

o m

assi

ve a

nd c

olla

pses

•Th

e iro

n co

re b

ecom

es n

eutro

ns w

hen

prot

ons a

nd

elec

trons

fuse

toge

ther

Den

sity

•Y

ou c

ould

take

eve

rybo

dy o

n Ea

rth a

nd c

ram

th

em in

to a

vol

ume

the

size

of s

ugar

cub

e

Expl

osio

n

•Th

e co

llaps

e of

the

core

rele

ases

a h

uge

amou

nt

of e

nerg

y si

nce

the

rest

of t

he st

ar c

olla

pses

and

th

en b

ounc

es o

ff th

e ne

utro

n co

re•

1044

-46

Joul

es•

Ann

ual e

nerg

y ge

nera

tion

of S

un is

1034

Joul

es

How

do

we

know

ther

e ar

e ne

utro

n st

ars?

•Th

e id

entif

icat

ion

of P

ulsa

rs•

Puls

ars g

ive

out p

ulse

s of r

adio

wav

es a

t pre

cise

in

terv

als

Puls

ars

•Pu

lsar

s wer

e fo

und

at th

e ce

nter

of s

uper

nova

e re

mna

nts

Puls

ars

•Pu

lsar

s wer

e in

terp

rete

d as

rota

ting

neut

ron

star

s•

Onl

y ne

utro

n st

ars c

ould

rota

te th

at fa

st•

Stro

ng m

agne

tic fi

elds

can

bea

m ra

diat

ion

out

Bla

ck H

oles

•If

a c

olla

psin

g st

ella

r cor

e ha

s a m

ass g

reat

er th

an

3 so

lar m

asse

s,•

It be

com

es a

bla

ck h

ole

Bla

ck H

ole

•A

fter a

supe

rnov

a if

all t

he o

uter

mas

s of t

he st

ar

is n

ot b

low

n of

f•

The

mas

s fal

ls b

ack

on th

e ne

utro

n st

ar•

The

grav

ity c

ause

s the

neu

tron

star

to k

eep

cont

ract

ing

Bla

ck H

ole

•A

bla

ck h

ole

is a

regi

on w

here

not

hing

can

es

cape

, eve

n lig

ht.

Even

t Hor

izon

•Ev

ent H

oriz

on is

the

boun

dary

bet

wee

n th

e in

side

an

d ou

tsid

e of

the

Bla

ck H

ole

•W

ithin

the

Even

tHor

izon

, the

esc

ape

velo

city

is

grea

ter t

han

the

spee

d of

ligh

t•

Not

hing

can

esc

ape

once

it e

nter

s the

Eve

nt

Hor

izon

How

do

calc

ulat

e th

e ra

dius

of t

he E

vent

Hor

izon

?•

It is

cal

led

the

Schw

arzs

child

Rad

ius

•R

adiu

s = 2

GM

/c2

•Th

is is

a v

aria

tion

of th

e es

cape

vel

ocity

form

ula

•Es

cape

vel

ocity

= sq

uare

root

(2G

Mpl

anet/R

plan

et)

Bla

ck H

ole

Size

s

•A

Bla

ck H

ole

with

the

mas

s of t

he E

arth

wou

ld

have

a ra

dius

of 0

.009

met

ers

•A

Bla

ck H

ole

with

the

mas

s of t

he S

un w

ould

ha

ve a

radi

us o

f 3 k

ilom

eter

s

Can

you

see

a B

lack

Hol

e?

No

•B

lack

Hol

es d

o no

t em

it an

y lig

ht•

So y

ou m

ust s

ee th

em in

dire

ctly

•Y

ou n

eed

to se

e th

e ef

fect

s of t

heir

grav

ity

Evid

ence

•Th

e w

hite

are

a is

th

e co

re o

f a G

alax

y•

Insi

de th

e co

re th

ere

is a

bro

wn

spira

l-sh

aped

dis

k.

•It

wei

ghsa

hun

dred

th

ousa

nd ti

mes

as

muc

h as

our

Sun

.

Evid

ence

•B

ecau

se it

is ro

tatin

g w

e ca

n m

easu

re it

s ra

diia

nd sp

eed,

and

hen

ce d

eter

min

e its

m

ass.

•Th

is o

bjec

t is a

bout

as l

arge

as o

ur so

lar

syst

em, b

ut w

eigh

s 1,2

00,0

00,0

00 ti

mes

as

muc

h as

our

sun.

•

Gra

vity

is a

bout

one

mill

ion

times

as s

trong

as

on

the

sun.

•

Alm

ost c

erta

inly

this

obj

ect i

s a b

lack

hol

e.

Que

stio

ns