ThursdaySeptember 13,

2012(The Protoplanetary Disk Model; Videos –

HTUW: Big Bang Parts 8 & 9)

The Launch PadThursday, 9/13/12

How is the life of a star affected by its initial mass at the time of its birth?

Low mass stars will burn for a very long time, then go straight from main-sequence

to white dwarf.Middle mass stars will burn for a long time, go to red giant, produce a planetary nebula,

and then go to white dwarf.High mass stars will burn for a short time, go to super red giant, then explode in a

supernova, producing either a neutron star or a black hole.

Announcements• Quiz 3 tomorrow.

Assignment Currently Open

Summative or

Formative?Date Issued Date Due Date Into

GradeSpeed Final Day

ESS Class Information Sheet F1 8/27 8/28

ESS Class Procedures and

ExpectationsF2 8/27 8/29

Quiz 1 S1 8/31 8/31 8/31 9/14Lab - Hubble’s

Law - the Expanding Universe

F3 9/4 9/6

Quiz 2 S2 9/7 9/7 9/7 9/21Lab – Timeline of the Universe

F4 9/11 9/13

WS – Star Stages

F5 9/12 9/13

??

Recent Events in ScienceA Celestial Witch’s Broom? A New View of the

Pencil Nebula

  The Pencil Nebula, a strangely shaped leftover from a vast

explosion: The oddly shaped Pencil Nebula (NGC 2736) is

pictured in this image from ESO’s La Silla Observatory in Chile. This

nebula is a small part of a huge remnant left over after a

supernova explosion that took place about 11 000 years ago. The image was produced by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla

Observatory in Chile. (Credit: ESO)

http://www.sciencedaily.com/releases/2012/09/120912084801.htmRead all about

it!

How the Universe

Works: The Big Bang

Part 8

The End of the Universe

Video

How the Universe

Works: The Big Bang

Part 9

Everything Starts With the

Big Bang

Video

The Birth of a Solar SystemThe history of our Solar System began

about 13.7 billion years ago with the Big Bang creation event. This provided the elements, along with later material from former stars, to form the solar system.Scientists now believe that our Milky

Way galaxy was formed very early in the history of the Universe, perhaps as early

as 950 million to 1 billion ABB. Our solar system, however, took another 8

billion years or so to form.

The Protoplanetary Disk Model

A protoplanetary disk is a

circumstellar disk of matter, including gas and dust, from which planets

may eventually form or be in the

process of forming.

The Protoplanetary Disk ModelThe existence of such disks

was long suspected, but was confirmed by direct imaging in 1994 when C.

Robert O'Dell and colleagues of Rice

University used the Hubble Space Telescope (HST) to examine newborn stars in the Orion Nebula. About

half of those were found to be surrounded by disks of

gas and dust.

The Protoplanetary Disk ModelAlso in 1994, John Stauffer

and associates of the Harvard-Smithsonian

Center for Astrophysics reported that 70 to 80 percent of infant stars at the center of the Orion Nebula

showed signs of having disks.

This high fraction has since been confirmed by more

sensitive observations by the Infrared Space

Observatory. 

The heavier elements were formed in many earlier stars and

supernovas.Dust, gas and

chemical compounds

began to concentrate in a region of space.

Supernova shockwaves

helped to “clump” the

matter.

The Protoplanetary Disk Model

A large, rotating nebula began to form. As a result of gravitational

contraction, the spin rate

increased. Most mass

concentrated in the central

proto-star. The remaining

material formed an accretion

disk. The material in the accretion disk

began to clump. The nebula

began to contract about 5 billion years

ago.

The protosun became a star.

The solar ignition flare-up may have blown

away the hydrogen and

helium atmospheres of inner planets.

The protoplanets

heated, separating

heavy and light minerals.

Larger bodies cooled slower,

with heavy materials

settling over longer times into central

cores.

The Protoplanetary Disk Model

http://www.daviddarling.info/encyclopedia/P/protoplandisk.html

The Protoplanetary Disk Model

http://www.youtube.com/watch?v=3YmeajE-TT8

http://www.youtube.com/watch?v=TUjJTNKO9FU