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b Flashcards

1
Q

Which element is NOT part of the World Geodetic System?

A

a. A parallel plane defined on the surface

The World Geodetic System includes gravitational equipotential surfaces, standard coordinate systems, and spheroidal reference surfaces.

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2
Q

Which two reference systems share the East-West axis?

A

b. Horizontal and Equatorial systems

The Horizontal and Equatorial systems both have the East-West axis in common.

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3
Q

What is the correct definition of Vernal Point?

A

c. intersection between the Equator and the Ecliptic

The Vernal Point marks the intersection of the celestial equator and the ecliptic plane.

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4
Q

Fill in the blank: The distance at which Earth’s radius subtends an angle of one arc minute is called _______.

A

[key learning term]

This refers to the concept of an astronomical unit.

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5
Q

Mark the WRONG sentence about the motion of the Sun.

A

a. The motion of the Sun on the sky is not uniform due to Earth eccentricity

The motion of the Sun is not primarily affected by Earth’s eccentricity.

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6
Q

Mark the WRONG definition among the proposed ones.

A

c. Sidereal Day: time between two consecutive passages of Vernal Point through the Local Meridian

A Sidereal Day is actually defined by the rotation of the Earth relative to distant stars.

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7
Q

Mark the WRONG sentence regarding the formation of spectral lines.

A

c. Absorption lines are formed when photons from a cold source pass through a hotter one

Absorption lines occur when cooler gas absorbs specific wavelengths of light from a hotter source.

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8
Q

Mark the correct sentence regarding the electromagnetic spectrum.

A

a. The energy associated with a photon decreases with increasing wavelength.

This is a fundamental principle of electromagnetic radiation.

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9
Q

Mark the WRONG sentence regarding the photometric color index of a star.

A

b. The color index is not affected by the stellar radius or the distance of the star

The color index can indeed be influenced by the distance and radius of the star.

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10
Q

Mark the WRONG sentence regarding the measurement of radiation.

A

c. A radiation field is isotropic if the intensity is independent of direction

Isotropic radiation means the intensity is the same in all directions.

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11
Q

Mark the WRONG sentence regarding different types of spectrographs.

A

b. Echelle spectrographs allow for extremely high resolution, but only for ground instruments

Echelle spectrographs can also be used in space-based observatories.

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12
Q

Mark the WRONG sentence regarding slit spectroscopy.

A

d. It allows high spectral resolution but its complexity makes it not suitable for space telescopes

Slit spectroscopy is often used in space telescopes despite its complexity.

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13
Q

What is the percentage of the main components of the primordial solar nebula?

A

a. Hydrogen and Helium 98%

The primary components of the solar nebula are predominantly Hydrogen and Helium.

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14
Q

Main differences between inner and outer planets include that _____ planets have higher _____ than the outer planets.

A

[key learning term]

Inner planets are typically rocky and have higher densities compared to the gas giants of the outer planets.

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15
Q

What is the main component of the Earth’s atmosphere?

A

c. Nitrogen

Nitrogen makes up about 78% of the Earth’s atmosphere.

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16
Q

What does the _____ depend on?

A

[key learning term]

This refers to the gravitational interaction between celestial bodies.

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17
Q

What are the shepherd satellites?

A

a. Small satellites orbiting among the rings of Saturn and also among the rings of other Giant planets

Shepherd satellites help maintain the structure of planetary rings.

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18
Q

How much bigger is the mass of Jupiter compared to that of the Earth?

A

d. 317 times

Jupiter’s mass is approximately 317 times that of Earth.

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19
Q

What is the main component of the Jovian planets?

A

d. Helium and Hydrogen

Jovian planets are primarily composed of Hydrogen and Helium.

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20
Q

How does the cometary ion tail form?

A

b. Interaction between cometary ions and solar wind

The solar wind ionizes the gas from the comet, forming the ion tail.

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21
Q

Which satellite in the Solar System has a thick atmosphere?

A

c. Titan

Titan, a moon of Saturn, has a dense atmosphere primarily of nitrogen.

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22
Q

Mark the WRONG sentence regarding the Main Sequence phase.

A

a. In the colour-magnitude diagram, Main Sequence stars are randomly scattered all across the diagram

Main Sequence stars are primarily located along a distinct band in the diagram.

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23
Q

Mark the WRONG sentence regarding the lifetime of a star radiating as the Sun.

A

b. Nuclear reactions keep a star in balance for billions of years only if all of its mass is converted to energy

Not all of a star’s mass is converted to energy; only a fraction is transformed during fusion.

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24
Q

Mark the WRONG sentence regarding the Carbon burning phase and beyond in stellar evolution.

A

d. Each nuclear burning phase converts the totality of the mass of the star in an element with higher atomic number

Only a portion of the star’s mass is converted during these phases.

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25
Mark the WRONG sentence regarding the nuclear fusion reactions in stars.
a. In the Sun 99% of the energy is produced by the proton-proton chain, and 91% by the ppl chain ## Footnote The proton-proton chain is the dominant source of energy but the percentages provided are incorrect.
26
Mark the WRONG sentence regarding white dwarfs.
c. Observed Hydrogen-Helium white dwarfs can only be the result of stellar evolution in binary systems ## Footnote White dwarfs can also form through single-star evolution.
27
Mark the WRONG sentence regarding black holes and compact objects.
c. From the outside, we would see the local clock of someone falling into a black hole increasing its speed exponentially ## Footnote An external observer would see the clock slow down as it approaches the event horizon.
28
Mark the WRONG sentence regarding the rotation of the Sun.
c. The Sun rotates at the same angular velocity from its equator to the poles, and it can be approximated to a rotating rigid body ## Footnote The Sun's rotation is differential; it rotates faster at the equator than at the poles.
29
Mark the WRONG sentence regarding the atmosphere of the Sun.
b. The solar atmosphere is divided into the corona (300-500 km thick) and the photosphere (over 500 km). The chromosphere extends much further out ## Footnote The chromosphere is actually situated between the photosphere and the corona.
30
Mark the WRONG sentence regarding the definition of planet/exoplanet.
a. A planet/exoplanet can orbit another planet or float free in space ## Footnote A planet or exoplanet must orbit a star to be classified as such.
31
Mark the WRONG sentence regarding the classification of exoplanet discoveries.
d. Candidate planet: a planet selected by the International Astronomical Union as a possible Earth 2.0 ## Footnote Candidate planets are those that have been identified through observation but have not yet been confirmed.
32
Mark the WRONG sentence regarding these properties of galaxies.
c. It is nearly impossible for galaxies to collide or merge. Structural properties are preserved since their formation. ## Footnote Galaxies do collide and merge, significantly affecting their structure.
33
Mark the WRONG sentence regarding stellar clusters and association.
a. The Messier and NGC catalogues include a careful selection of open and globular clusters, with all possible constellations and asterisms cleaned out ## Footnote The catalogues include a variety of astronomical objects, not strictly clusters.
34
Mark the WRONG sentence regarding the properties of galaxies.
d. Small galaxies do exist isolated from other galaxies, and they never orbit larger galaxies ## Footnote Small galaxies can orbit larger galaxies and are often found in clusters.
35
Mark the WRONG sentence regarding the classification of exoplanets.
d. Warm Jupiter/Neptunes: gas giants with temperature adequate to host liquid water ## Footnote Warm Jupiters typically do not have conditions suitable for liquid water due to their gaseous nature.
36
Mark the WRONG sentence regarding white dwarfs.
b. White dwarfs are very cold, so they are dim (low luminosity) despite their large size (several solar radii) ## Footnote White dwarfs are not large; they are typically about the size of Earth.
37
What is a mean motion resonance?
c. The orbital periods of two (or more) objects are related by a ratio of small integers ## Footnote Mean motion resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other.
38
Mark the WRONG sentence regarding the Sun.
b. In the Sun, only 19% of the energy is produced in the core ## Footnote The majority of the Sun's energy is produced in its core through nuclear fusion.
39
What is the relationship between the rotational periods of two objects?
The rotational periods of two objects are related by a ratio of small integers.
40
What is the relationship between the orbital periods of two objects?
The orbital periods of two (or more) objects are related by a ratio of small integers.
41
What is synchronization in the context of celestial mechanics?
It is the synchronization of the perihelion precession and of the ascending node.
42
What is the composition of the Sun's core?
In the core, 5% of the primordial Hydrogen has been converted to Helium.
43
What percentage of the Sun's energy is produced within 0.25 solar radii?
Only 19% of the energy is produced within 0.25 solar radii.
44
What is the role of neutrinos in studying the Sun?
The observation of neutrinos from the core of the Sun has permitted their mass determination.
45
What are sunspots?
Sunspots are large regions (10000 km) in the photosphere that are around 1500K colder than the surroundings.
46
What causes solar activity phenomena?
Differential rotation will cause the magnetic field to get wrapped and emerge from the surface.
47
What is a pulsar?
Only a small number of neutron stars emits a radio beam sweeping the sky regularly, and all of them take the name of pulsars.
48
What is the effect of mass on the structure of stars?
Stars become brighter, hotter (on surface), and less dense with increasing mass, but only for Main Sequence stars.
49
What is the CNO cycle's sensitivity to temperature?
The CNO cycle is less sensitive to temperature, so in massive stars nuclear reactions occur at a much slower rate.
50
What happens to white dwarfs as mass increases?
Increasing the mass causes smaller radius.
51
What keeps a star in balance for billions of years?
Nuclear reactions keep a star in balance for billions of years.
52
What defines hydrostatic equilibrium in stars?
In hydrostatic equilibrium, gravity and pressure counterbalance each other everywhere.
53
What does the Vogt-Russell theorem state?
The structure of a star, under given approximations, is uniquely determined by its mass and composition.
54
What is characterized by Helium burning in the core of a star?
The horizontal branch phase.
55
What is the main gaseous component of Titan's atmosphere?
Nitrogen.
56
Why are the outer planets bigger than the inner planets?
Outer planets formed in a region in which more material condensed.
57
What is the origin of Jupiter's strong magnetic field?
A wide layer of liquid metallic hydrogen in its interior.
58
Where do short period comets come from?
The Kuiper Belt region.
59
Where is the Main Belt located?
Between the orbit of Mars and Jupiter.
60
What is the most abundant ice in a comet?
H2O.
61
How does the cometary dust tail form?
Interaction between cometary dust and solar radiation pressure.
62
Which planet has the lowest density among the eight in the Solar System?
Saturn.
63
What can be determined from spectral lines?
Temperature and gravity can be iteratively determined when many lines of a given element are available.
64
What defines the apparent magnitude of a star?
The apparent magnitude is defined as the magnitude measured at a distance of 10 parsecs from the star.
65
What is the relationship between apparent and absolute magnitude?
The difference between apparent and absolute magnitude is called distance modulus.
66
What is the effect of annual aberration for a star with ecliptic latitude equal to 45 degrees?
The star describes an ellipsis with one axis perpendicular to the Ecliptic.
67
What are Near Earth Objects?
Objects (asteroids and/or comets) with high probability to impact the Earth.
68
What defines a circumpolar star in the Northern Hemisphere?
A star is circumpolar if its declination is higher than the zenith angle of the North Pole.
69
What is the definition of the Habitable Zone?
A planet in the Habitable zone can support liquid water on the surface, given sufficient atmospheric pressure.
70
What are Super-Earths?
Planets slightly larger than Earth, rocky with a thin atmosphere.
71
What happens when a star passes the Chandrasekhar limit?
Electron degeneracy pressure is insufficient to balance the star's own gravitational compression.
72
What is the main process in the core of intermediate-mass stars?
Energy in the core is produced by the proton-proton cycle and Carbon-Nitrogen-Oxygen cycle in equal parts.
73
What type of core do intermediate-mass stars have?
A radiative core surrounded by a convective envelope
74
What allows an extended lifetime of intermediate-mass stars?
A small transfer of material from the convective zone to the core
75
Which cycles produce energy in the core of intermediate-mass stars?
Proton-proton cycle and Carbon-Nitrogen-Oxygen cycle in equal parts
76
What is the typical lifetime of intermediate-mass stars?
Several billions of years
77
What is a characteristic of Venus in the Solar System?
It has a retrograde rotation
78
How long is the orbital period of Jupiter?
About 12 terrestrial years
79
What is the main component of Mars' atmosphere?
Carbon dioxide CO2
80
Why does Venus lack a magnetic field?
Because of its slow rotation
81
What is the origin of Jupiter's strong magnetic field?
A wide layer of liquid metallic hydrogen in its interior
82
What distinguishes primary atmospheric composition from secondary?
The primary atmosphere is made of Hydrogen and Helium
83
What can be determined from spectral lines?
Temperature and gravity can be iteratively determined
84
What defines an isotropic radiation field?
Intensity is independent of direction
85
What is luminosity proportional to?
The inverse of the square of the distance of the source
86
What happens in an optically thick cloud?
Emission and absorption processes are in equilibrium
87
What does blackbody radiation depend on?
Temperature
88
What calendar is currently in use?
The Gregorian calendar
89
Which time standard is affected by the Earth's rotation?
UT1
90
What is not needed to define a celestial coordinate system?
The radius of the sphere where the celestial objects are projected
91
What is the difference between Apparent and Mean Sidereal Times called?
Equation of Equinoxes
92
What happens when a massive star's core collapses?
It leads to a supernova explosion
93
How do high-mass stars differ in structure?
They have a convective core surrounded by a radiative envelope
94
What defines Right Ascension?
Distance of the star from the Vernal Point along the Equator, measured clockwise
95
What is a characteristic of alt-azimuthal mounts?
No restrictions in pointing, except for the North pole
96
What is true about the Earth's temperature at aphelion?
The average temperature is lower than at perihelion
97
What does the magnitude of a star do with decreasing flux density?
Increases logarithmically
98
What technique relies on light beam interference?
Gratings
99
What do O-B-A classes include?
Blue-white stars with temperatures between 50,000 and 7,500 K
100
What is the most unusual property of Uranus?
The inclination of its axis
101
What happens in the asymptotic giant phase?
The star loses its outer envelope, forming a planetary nebula
102
What prevents further collapse of neutron stars?
Neutron degeneracy pressure
103
What is true about black holes?
Light cannot escape if mass is contained within its Schwarzschild radius
104
What is true about open clusters and associations?
They provide information on the shape of the Milky Way
105
What defines modern photometric systems?
Description of the filter response as a function of wavelength
106
What is the main component of Venus' atmosphere?
Carbon dioxide
107
What is the least successful method for planet detection?
The Transit technique
108
What can a meridian telescope measure?
The right ascension and declination of a star
109
What is a cause of perturbation of coordinates not related to Earth's movements?
Refraction
110
What is a characteristic of Venus?
A thick atmosphere
111
Which mission is not dedicated to exoplanets?
EUCLID - European Constellation for exoLife Detection
112
What is a characteristic of the Bohr model of an atom?
The energy level of electrons cannot assume arbitrary values ## Footnote According to the Bohr model, electrons can only occupy certain allowed energy levels.
113
What is the point in the colour-magnitude diagram where the star leaves the Main Sequence to enter the Giant phase called?
The Turn-Off ## Footnote This is a critical point in stellar evolution.
114
What is the boundary between the Kuiper Belt and the Oort Cloud?
The frost line ## Footnote This is a region in the solar system that defines where different materials can condense.
115
Mark the system that is exclusively topocentric.
Horizontal system ## Footnote This system is based on an observer's local horizon.
116
Mark the wrong sentence regarding flux and luminosity.
The flux density and the Solar constant do not depend on the distance of the source ## Footnote Both flux density and Solar constant vary with distance.
117
What is the definition of Hour Angle?
Distance of the star from the Local Meridian along the Equator, measured clockwise ## Footnote Hour Angle is crucial for astronomical observations.
118
Mark the wrong sentence regarding neutron stars.
During the final collapse of a star, the totality of its mass is converted to neutrons, with no ejection of matter ## Footnote Matter is typically ejected during a supernova event.
119
In the asymptotic giant phase of stellar evolution, what happens when Helium in the core is exhausted?
Helium keeps burning in a shell, leaving behind a Carbon and Oxygen core ## Footnote This marks a significant phase in the life of intermediate-mass stars.
120
What do we call the visual representation of The Equation of Time?
The analemma ## Footnote It illustrates the discrepancy between mean solar time and apparent solar time.
121
Mark the wrong sentence regarding the properties of light.
Photons are packets, or quanta, of continuous and variable amounts of energy ## Footnote Photons have discrete amounts of energy, determined by their frequency.
122
What is an isochrone?
Luminosity and temperature of an ensemble of stars with the same age and chemical composition, over a wide range of mass ## Footnote Isochrones are used in stellar evolution studies.
123
Mark the wrong sentence regarding the structural properties of galaxies.
Bars are thought to be streams of gas from the spirals to the centre of the galaxy ## Footnote Bars are structures that can influence the dynamics of a galaxy.
124
What does the flux measure?
The power going through a surface, measured in Watts ## Footnote Flux is essential in understanding energy transfer in astrophysics.
125
True or False: The luminosity of a star is constant regardless of the distance from the observer.
True ## Footnote Luminosity is an intrinsic property, while flux varies with distance.
126
Fill in the blank: The star will lose the outer envelope into space, the expelled material takes the name of _______.
Planetary Nebula ## Footnote This process occurs in the later stages of stellar evolution.
127
What type of stars do low-mass stars evolve into at the end of their life?
Carbon-Oxygen white dwarfs ## Footnote These stars cool down slowly over time.
128
What is the effect of the Earth's orbital eccentricity on timekeeping?
It greatly influences the Equation of Time ## Footnote The Earth's varying distance from the Sun affects solar time measurements.

analisi 2 (3 decks)

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