We have learned that the centre of the milky way contains a very massive black hole. We developed this
understanding by: - Monitoring the orbital motions of many individual stars in the very central parts
of the Milky Way
If the sun were to be squashed down small enough to become a black hole, t...
ASTR 102 Quiz Questions | 100% Correct
Answers | Verified | Latest 2024 Version
We have learned that the centre of the milky way contains a very massive black hole. We developed this
understanding by: - ✔✔Monitoring the orbital motions of many individual stars in the very central parts
of the Milky Way
If the sun were to be squashed down small enough to become a black hole, then: - ✔✔The planets in the
solar system would orbit the Sun in unchanged fashion (but would receive no light from it)
The first stellar mass black hole identified, Cygnus X-1, was found in 1973. The name is a clue to what led
to the discovery, namely: - ✔✔a source of X-rays was found in Cygnus. In a binary system one star is
losing material into the potential well of a dense object? a black hole
In studying interstellar material, we:
a) use vacuum chambers on earth to simulate the conditions between the planets (but cannot simulate
the conditions in true interstellar space)
b) use vacuum chambers on earth to simulate the conditions between the stars
c) send out space probes to bring back samples from the low-density near-vacuum regions
d) have to rely on observations since we cannot come close to simulating those conditions here on Earth.
- ✔✔d) have to rely on observations since we cannot come close to simulating those conditions here on
Earth.
Will the Sun end its life in a nova? - ✔✔it cannot, because the sun is not in a binary star system with a
close companion star
The interstellar medium contains dust, and we have to worry about what effect it will have on our
observations. Careful analysis tells us that - ✔✔the remote stars look fainter and redder than they
should, but the spectra reveal the true nature of the stars under scrutiny
What happens when a more massive star transfers some material to a close companion of lower mass -
✔✔the companion experiences a shorter life because of the extra mass compresses the star, making it
hotter and increasing the nuclear reactions.
,We first learned about the existence of rather complex multi-molecules in interstellar space by -
✔✔using radio telescopes to detect characteristic emission given off when the molecules abruptly
change their rates of rotation or vibration
Astronomers were surprised to find multi complex multi-atom molecules in interstellar space because -
✔✔Such molecules would very likely be disrupted completely by the energetic photons streaming
through interstellar space
Einsteins general relativity has real consequences in day-to-day life, namely: - ✔✔in the system of GPS
satellites, high up in the Earth's gravitational potential well, clocks run at different rates than here at
ground level
When new stars are forming, they appear first as: - ✔✔bright infrared sources because they are in the
form of very large distended warm gas clouds
When a very massive cloud of gas (say 1000 times the mass of the sun) condenses under gravity, it ____ -
✔✔will fragment into smaller pieces to form a cluster of stars
A good way of finding a compact binary star system is to look for - ✔✔X-rays that are formed when
atoms in the mass-transfer stream collide with the swirling disk of material and heat it up.
When we look at large clusters of galaxies, we sometimes see rings, or parts of rings of light surrounding
them. this is caused by what? - ✔✔caused by the gravitational lensing of remote background objects,
the light of which passes the massive cluster of galaxies on its way to us.
The black hole at the centre of the M.W has a mass of: - ✔✔mass of several million times the mass of
the sun
Large numbers of Mini Black holes, with the mass of an asteroid, could have been created in the early
universe. If so, we might detect them by: - ✔✔detecting present day bursts of gamma radiation as they
evaporate by Hawking Radiation
Van de Hulst was the first to predict something important about neutral hydrogen in the interstellar
medium. He realized that it should: - ✔✔it should emit a photon from a spin-flip transition within the
atom.
, More than 2 centuries ago, Laplace hypothesized that very massive stars might exist and yet be invisible.
He speculated that the light would: - ✔✔light emitted y such a star would start moving outward but be
slowed by gravity, come to a halt, and fall back down.
When we detect the presence of a black hole in the MACHO project, we then: - ✔✔there is nothing
more to be done: as the black hole continues its motion, its gravitational effect on the stars light never
returns.
Giant Molecular Clouds (GMCs) in the M.W may contain as much as ____ solar masses of material:
mostly ______ and ______, but including many ________. - ✔✔100,000 solar masses; mostly hydrogen
and helium, but including many complex molecules
The trajectory of light is determined by - ✔✔determined by distortions in space that are caused only by
the rare very massive objects
The famous 21 cm emission from neutral hydrogen gas was predicted in 1944. it is particularly important
because - ✔✔this long-wavelength radiation is of relatively high energy, which explains why the gas
clouds in the M.W are glowing: it is because of fluorescence
Black holes of small mass (like the mass of an asteroid) could have been created: - ✔✔could have been
created in large numbers in the early universe and so could be all around us in the universe
A "MACHO" strategy for searching for black holes has been used in recent years and involves: -
✔✔looking at crowded star fields to see if any stars temporarily brighten up as a black hole passes
between us and them. gravitationally focussing the light.
When mass is transferred in a binary star system it forms a - ✔✔forms a whirlpool like disk around the
receiving star because of the mutual orbital motion of the stars
Interstellar dust grains absorb light, which is a form of energy. as a result, the dust: - ✔✔the dust grains
glow at infrared wavelengths
In a close binary star system, matter will certainly flow from - ✔✔the more massive star to the low mass
star because the more massive star expands as it evolves
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