Astronomy Final

Suppose a galaxy that follows the Hubble-Lemaitre law has a type Ia supernova go off, revealing that it is 80 million light years away. What would you expect its recessional velocity to be, from its spectrum?

1800 km/s

Suppose a main sequence star was discovered in the Milky Way that was determined to be approximately 1 million years old, describe the star

M-type, Population I, open cluster star, O-type, high heavy element abundance, disk star

Distinguish between Population I and Population II stars

Population I: open cluster stars located in the galactic disk generally higher heavy element abundance young and old Population II: Located in the galactic disk and halo globular cluster stars generally lower heavy element abundance generally older

The standard bulbs that made it possible for astronomers to discover the acceleration in the expansion of the universe were?

Type Ia supernova

According to the general theory of relativity, light and other radiation coming from a white dwarf or a neutron star should (and experiments show that it does) exhbit

a gravitational redshift

How do astronomers know that there aren't significant amounts of dark matter within our solar system?

a lot of dark matter would affect the motions of our spacecraft as they move though the solar system, and we see no such effect

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is?

about 13.8 billion years

Where in the Galaxy would you expect to find type Ia supernovae?

all of these options

Suppose each of the following objects collapse into a black hole. Each black hole would have a sphere around it that is the limit for escape -- once you are inside this region, you cannot get awayhor which object would this region be the largest diameter?

an entire galaxy of star ( with about a billion stars in it)

According to the general theory of relativity, the presence of mass

causes a curvature (or warping) of spacetime

Put the following objects in order of distance, from the closest to the furthest away

closest: the crab nebula -the Andromeda galaxy -the black hole at the center of galaxy M87 -Quasar 3C272 Furthest: a quasar whose redshift indicates it is moving away at 90% the speed of light

Arrange the selected events in the model of the early universe in chronological order, from earliest to latest

earliest: inflation -matter particles appear -fusion creates deuterium and helium -nuclei capture electrons, forming atoms latest: CMB photons free to travel

Arrange the steps in how astronomers currently think the Milky Way formed from earliest to latest

earliest: massive cloud of gas begins collapsing halo stars and globular clusters form disk of gas collapses forming disk stars latest: mergers further build up the Milky Way

Based on the fact that the central galaxy has been redshifted out of visible wavelengths, what type of galaxy is it most likely to be?

elliptical

Which properties of our universe are well-explained by the standard Big Bang model and which properties are not well explained?

explained: CMB blackbody spectrum, light element abundances, expansion of the universe not explained: flat geometry of the universe, density of the universe equals the critical density, uniformity of the universe

An astronomer needs to measure the distance cluster of stars that is part of the Milky Way galaxy. What method should she try to use to find the distance?

find a variable star (cepheid or RR lyrae) in the cluster

What method would astronomers use to find the distance to a remote quasar?

finding the redshift and using Hubble's law

Hubble's discovery of the existence of other galaxies happened roughly 100 years ago. Human civilization had been around 11000 years now.For what fraction of the existence of human civilization have humans understood the true geography of the universe?

fraction= 9.091E-3

When one member of a binary star system is a black hole, and astronomers detect flickering x-rays coming from the system, where are these x-rays usually coming from?

from a disk of material around the black hole ( material that has been pulled from the companion star and is falling toward the black hole

Which statement best explains why not every galaxy falls on the line?

galaxies are often in clusters, and have some motion within the cluster that moves it off the line

Astronomers believe that the universe has a flat geometry because

hot and cold features in the CMB have a characteristic size of about one degree on the sky

How does a period of extremely fast inflation very early in the history of the universe explain the observation that the geometry of the universe looks flat to us?

inflation increased the size of the universe is much that the resulting universe looks flat from any point of view

The color of this galaxy indicates that (yellow-white)

it is undergoing no significant star formation or it has no stellar population

The blue appearance of this galaxy indicates that

it is undergoing significant star formation

arrange the objects in order of how much an escaping light wave will exhibit gravitational redshirting, from lowest to highest

lowest- pangolin earth jupiter the sun highest- white dwarf

Arrange the objects in order of how much x-rays energy will be emitted by an accretion disk around the object, from lowest to highest

lowest- prostar white dwarf neutron sta highest- black hole

Put the following objects in order of mass, from lowest mass to the highest mass

lowest:earth typical white dwarf typical neutron star black hole in cygnus black hole at the center of the milky way Highest: black hole at the center of galaxy M87

What characteristic of the universe determines which of these models is the correct one?

mass-energy density

Which statement accurately described this relationship between the central black hole and the mass of that galaxy's central bulge?

more massive galaxy bugles contain more massive black holes

Why is the use of Hubble's law to measure distances to galaxies so important to astronomers?

most galaxies are so far away, the only way to get distances to them is to use Hubbles's law

If one were to try to represent light on this pie chart, how would its wedge compare to the other categories?

much less than ordinary matter

From the characteristics listed below, distinguish between the characteristics of nearby galaxies and more distant galaxies

nearby: fewer major merger events, more developed structure as a whole, fewer quasars, less star formation as a whole Distant: more quasars, undeveloped structure, more major merger events, more star formation as a whole

Harlow Shapley determined the location of the Galactic center using positions of globular clusters. Were open clusters a viable option?

no, Shapely could not have used open cluster because they lacked good distance indicators and lie only in the Galactic disk so dust more heavily obscures their appearance at large distances across the Galaxy

Edwin Hubble's tuning fork diagram indicated that he believed elliptical galaxies gradually evolved into spiral galaxies. Based on what astronomers now know, can this happen?

no; elliptical galaxies have no gas, so they have nothing with which to form spiral arms and young stars. no; elliptical galaxies have little to no coherent rotation so they could never collapse down to a disk shape

Arrange the astronomical objects in order of size from smallest to largest

smallest- event horizon of three solar-mass blackhole white dwarf jupiter the sun largest- b type MS star

In which type of galaxy are you likely to observe a type II supernova?

spiral, irregular

When we determine the age of the universe using the Hubble time, what important simplifying assumption goes into our calculations?

that the expansion of the universe has been happening at the same rate - neither speeding up or slowing down

If therefore the large ellipticals are in the foreground and the lined galaxies are in the background, why do the background galaxies still have a bluer appearance?

the background galaxies were forming stars at such a high rate, producing so much UV light, that even significant redshirting still left them brightest in blue wavelengths

What does the slope of this graph represent?

the expansion rate of the universe

The galaxy itself, in the center with a redshift of about 0.35, has largely been redshifted out of visible wavelengths, allowing the four bright points of light around it to be dramatically seen. What is the best explanation for what we are seeing here?

the galaxy is gravitationally lensing a background quasar, with an alignment that has produced four lensed quasar images

How do astronomers explain the energetic jets that come out of quasars and active galactic nuclei in opposite directions?

the jets are spit out from the chaotic accretion disks of supermassive black holes in directions that are perpendicular to the disk

How do quasars demonstrate that the universe evolves with time?

the number of quasars reached a maximum some time ago, and now the numbers have been declining

Which of the following is evidence that the formation process of our Galaxy may have included collisions with smaller neighbor galaxies?

the observation of long moving streams of stars that continue to orbit through our galaxy's halo

What leads astronomers to conclude that the proto-galactic cloud (the cloud from which our Galaxy formed) was roughly spherical?

the oldest stars in the Galaxy (Population II star, globular clusters) form a spherical halo around the Galaxy, they outline the original shape of the cloud that gave the Galaxy birth

Suppose you and an astronaut colleague visit a black hole. You remain outside the event horizon in the spaceship, while your colleague sacrifices themself for the love of science by diving directly into the black hole. What would your colleague observe of you as they fall toward the event horizon?

the spaceship's signal beacon speeds up and the spaceship's appearance gets bluer

If quasars often resemble little blue stars, what was it about them that so surprised astronomers when they were discovered?

their spectral lines were at first hard to recognize and then turned out to have large redshifts

Astronomers have discovered two giant bubbles above and below the central region of our Milky Way galaxy that give off large amounts of gamma rays. What do they think is one possible origin for these so called "Fermi Bubbles"?

they were formed by energetic jets produced by the milky way's central black hole when a significant amount of matter fell in a few million years ago

Where in the Galaxy would you expect to find Type II supernovae?

thin disk

Suppose you were on an interstellar journey and during hyper sleep your spaceship accidentally flew into a black hole, crossing the event horizon. Waking up quickly and seeing that you are heading toward the singularity , you decide to veer left and turn the ship completely around, firing the thrusters at full throttle. Which direction are you now heading?

toward the singularity

If our Milky Way's black hole has a mass of 4 million solar masses, what is the mass of the milky way's central bulge?

two billion solar masses

Put the four forces of nature in order of relative strength, from weakest to strongest

weakest: gravity -weak nuclear force -electromagnetism strongest: strong nuclear force

arrange each star indicating what the likely final stage in its evolution will be

white dwarf- most massive a-type main sequence star, most massive m-type main sequence star, most massive g-type main sequence star Neutron star- most massive b-type main sequence star Black hole- most massive o-type main sequence star

Which is likely to be more common in our galaxy: white dwarfs or black holes

white dwarfs, because they arise from low mass stars which from in higher abundance than do the high mass stars that produce black holes

Can spiral galaxies turn into elliptical galaxies?

yes; if a spiral galaxy interacts with another large galaxy then a flurry of star formation happens, which can use up all of the gas and eventually lead to a red and dead stellar population. yes; if a spiral galaxy interacts with another large galaxy this will disrupt its structure and result in a stellar population that orbits in all directions