unit 11/12 Flashcards
5/2/24
the study of electromagnetic spectra— provides important information about the chemical composition of remote astronomical objects.
Spectroscopy
serve as distinctive “fingerprints” that identify the chemical elements and compounds comprising a light source.
Spectral Lines
A device that separates incoming light by its wavelengths AND records the spectrum.
Spectrograph
Usually starts from a source that gives off all wavelengths of light (like a star), but is missing specific wavelengths that were absorbed on its way to us
Absorption Spectrum
The specific set of wavelengths emitted by a source.
Emission Spectrum
When the source and observer are moving towards each other, the observed wavelength is shorter. Therefore, the frequency (pitch) is higher.
When the source and observer are moving away from each other, the observed wavelength is longer. Therefore, the frequency (pitch) is lower.
The Doppler Effect & Sound
When the source and observer are moving towards each other, the observed wavelength is shorter. Therefore, the color is blueshifted.
When the source and observer are moving away from each other, the observed wavelength is longer. Therefore, the color is redshifted.
The Doppler Effect & Light
Moving away from us
the further away the astronomical object is, the faster it is moving away from us.
Redshift
an idealized perfect light absorber that absorbs all the photons that strike it (no reflection). It re-emits the absorbed energy through thermal radiation,
Blackbody spectrum
states that the peak wavelength of radiation emitted by a blackbody is inversely proportional to its temperature - the higher its temperature, the shorter the peak wavelength.
Wien’s Law
a scientific field within the life and environmental sciences that studies the origins, early evolution, distribution, and future of life in the universe.
Astrobiology
Godi lock Zone: a planet where water can exist as a liquid, not too hot or too cold for life.
depends on the star’s size and temperature, and the planet’s atmosphere and distance.
Bigger and hotter stars have wider and farther habitable zones, while smaller and cooler stars have narrower and closer ones.
Habitable Zones
used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy
The DRAKE equation
Which of the following are colors of stars that you can see?
Blue, white, yellow, orange, and red
What color are the hottest stars?
blue
What color are the coolest stars?
red
Our star, The Sun, gives off more green light than any other visible color of light. So, why does our Sun not look green
The sun appears orangish-yellow because the blue light it emits has a shorter wavelength and is scattered in the atmosphere—the same process that makes the sky appear blue. Astronomers, however, call the sun a “yellow dwarf” star because its colors fall within the yellow-green section of the electromagnetic spectrum.
A star has a surface temperature of 7000 K. What color is it?
white or slightly yellowish in color.
The color of a star is an indication of its surface temperature: blue stars are the hottest, followed by white, yellow, orange, and red being the coolest.
Do humans emit light?
yes, visible light
You see an orange star through a telescope. What is a possible surface temperature for that star?
3,500–5,000 K
Do stars only emit visible light?
no
the hottest stars to the coolest star
O
B
A
F
G
K
M
exceeding 30,000 K
blue-violet
O
between 10,000 and 30,000 K
blue-white
B
between 7,500 and 10,000 K
white
A
Is the universe expanding or contracting?
expanding
below 3,500 K
red-orange
M
The greater the shift the ___ the star is moving?
faster
between 6,000 and 7,500 K
yellow-white
F
In general, the further away a star is from us, the __ (lesser/greater) the shift in its spectra.
greater
Is most star spectra red or blue shifted?
red shifted
between 5,500 and 6,000 K
yellow
G, sun like stars
between 3,500 and 5,000 K
orange
K
Are Blue Shifted stars moving away or toward us?
Toward Us
Are Red Shifted stars moving away or toward us?
Away from us
Are Stars that have no shift stationary, moving away from us, or toward us?
stationary
Can we actually see dark matter with our eyes or telescopes?
No you cant see it at all
What does SETI stand for
Search for extraterrestrial intelligence
What are some requirements for the planetary habitable zone?
It has to be a comfortable distance away from a star (Habitable Zone)
The stars around it have to be ‘stable’.
It should not have a very low or very high mass.
It must rotate on its axis and revolve.
It should have a molten core.
It should hold an atmosphere.
It should contain liquid water and other compounds that are required for life.
What are some requirements for the galactic habitable zone?
sufficient heavy elements like iron, magnesium, titanium, carbon, oxygen, and silicon to form Earth-like planets
A low occurrence of catastrophic events such as supernovae or close stellar encounters to allow complex life forms to evolve
A location that is not too close to the galactic center to avoid the intense gravitational forces and higher occurrence of catastrophic events
Describe some of the requirements for life
1) Biogenic elements like carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur
2) source of energy, which could be light or chemical
3) liquid water
4) suitable environment for evolution
Can we actually see dark energy with our eyes or telescopes?
no
What are some examples of why we think dark energy is there?
What are some examples of why we think dark matter is there?
How is dark energy related to the expansion of the universe?
Gravity pulls galaxies closer together; dark energy pushes them apart. Whether the universe is expanding or contracting depends on which force dominates, gravity or dark energy.
