INTERSTELLAR MOLECULES IN THE VACUUM OF SPACE

Discuss the nature and significance of interstellar molecules.

OBJECTIVE

• Most of space is empty• Areas that aren't empty are filled with millions of tons of

gas, and dust• Gas is primarily composed of Hydrogen, and smaller

amounts of other molecular bits and pieces.

INTERSTELLAR SPACE

• Interstellar means “in between stars”• The Interstellar Medium.• gas in ionic, atomic, and molecular form, dust, and cosmic

rays

WHAT DOES INTERSTELLAR MEAN?

• Interstellar Molecules are the basic parts of every star • Over time, clouds of molecules gather in clouds.• Clouds eventually accrete and form the earliest parts of

protostars

• Over much more time, protostar forms a star, and begins burning

INTERSTELLAR MOLECULES

• Many kinds of molecules can be found inside the vacuum of space.

• And not all molecules eventually form stars.• There exists an interstellar cloud of nothing but pure

alcohol. Raise your mug to that.• There are also many basic parts of amino acids in these

clouds. • Some astrobiologists think that the foundations of life

may have risen in these free-floating clouds of organic matter.

INTERSTELLAR ODYSSEY

Table 1: Components of the interstellar medium[2]

Component FractionalVolume

Scale Height(pc)

Temperature(K)

Density(atoms/cm³)

State of hydrogen

Primary observational

techniques

Molecular clouds

< 1% 80 10—20 102—106 molecular

Radio and infrared

molecular emission and absorption

linesCold Neutral

Medium (CNM)

1—5% 100—300 50—100 20—50 neutral atomic

H I 21 cm line absorption

Warm Neutral Medium (WNM)

10—20% 300—400 6000—10000 0.2—0.5 neutral atomic

H I 21 cm line

emission

Warm Ionized Medium (WIM)

20—50% 1000 8000 0.2—0.5 ionizedHα emission

and pulsar dispersion

H II regions < 1% 70 8000 102—104 ionizedHα emission

and pulsar dispersion

Coronal gasHot Ionized

Medium (HIM)

30—70% 1000—3000 106—107 10−4—10−2

ionized(metals also

highly ionized)

X-ray emission;

absorption lines of highly ionized metals,

primarily in the

ultraviolet

BOOK

• Average size of an atom is 10^-10 m across (or .1 nm) • REDDENING –Light is stripped of “blue” side of

wavelength.• Extinction

• Emission and Reflection nebulae