Parallax, Magnitudes, Spectral Classes & HR Diagrams

Parallax, Magnitudes, Spectral Classes & HR Diagrams

I. Parallax A. Parallax is the _________________ to determine the ________ to stars. Parallax only works for _________ stars. B. Parallax is the apparent ______ of a “nearby” star with respective to the background stars when viewed ______ _______________. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at ___ _________________________. C. An example of this is when you hold your finger ___________ ________________and view it first with ________ and then the _________. D. The term parallax is derived from the Greek word “parallaxis”, which means _________. E. Nearby objects have a ______ parallax than more distant objects. Therefore, the further away a star is, the _____ ___________ to measure its parallax.

I. Parallax A. Parallax is the _only direct method_ to determine the _distance_ to stars. Parallax only works for _“nearby” _ stars. B. Parallax is the apparent ______ of a “nearby” star with respective to the background stars when viewed ______ _______________. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at ___ _________________________. C. An example of this is when you hold your finger ___________ ________________and view it first with ________ and then the _________. D. The term parallax is derived from the Greek word “parallaxis”, which means _________. E. Nearby objects have a ______ parallax than more distant objects. Therefore, the further away a star is, the _____ ___________ to measure its parallax.

I. Parallax A. Parallax is the _only direct method_ to determine the _distance_ to stars. Parallax only works for _“nearby” _ stars. B. Parallax is the apparent _shift_ of a “nearby” star with respective to the background stars when viewed _from 2 different positions_. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at _2 different times during the year_. C. An example of this is when you hold your finger ___________ ________________and view it first with ________ and then the _________. D. The term parallax is derived from the Greek word “parallaxis”, which means _________. E. Nearby objects have a ______ parallax than more distant objects. Therefore, the further away a star is, the _____ ___________ to measure its parallax.

I. Parallax A. Parallax is the _only direct method_ to determine the _distance_ to stars. Parallax only works for _“nearby” _ stars. B. Parallax is the apparent _shift_ of a “nearby” star with respective to the background stars when viewed _from 2 different positions_. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at _2 different times during the year_. C. An example of this is when you hold your finger _up in front of you at arms length_ and view it first with _one eye_ and then the _other eye_. D. The term parallax is derived from the Greek word “parallaxis”, which means _________. E. Nearby objects have a ______ parallax than more distant objects. Therefore, the further away a star is, the _____ ___________ to measure its parallax.

I. Parallax A. Parallax is the _only direct method_ to determine the _distance_ to stars. Parallax only works for _“nearby” _ stars. B. Parallax is the apparent _shift_ of a “nearby” star with respective to the background stars when viewed _from 2 different positions_. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at _2 different times during the year_. C. An example of this is when you hold your finger _up in front of you at arms length_ and view it first with _one eye_ and then the _other eye_. D. The term parallax is derived from the Greek word “parallaxis”, which means _alteration_. E. Nearby objects have a ______ parallax than more distant objects. Therefore, the further away a star is, the _____ ___________ to measure its parallax.

I. Parallax A. Parallax is the _only direct method_ to determine the _distance_ to stars. Parallax only works for _“nearby” _ stars. B. Parallax is the apparent _shift_ of a “nearby” star with respective to the background stars when viewed _from 2 different positions_. Because of Earth’s orbit around the Sun, this happens when astronomers view a “nearby” star at _2 different times during the year_. C. An example of this is when you hold your finger _up in front of you at arms length_ and view it first with _one eye_ and then the _other eye_. D. The term parallax is derived from the Greek word “parallaxis”, which means _alteration_. E. Nearby objects have a _larger_ parallax than more distant objects. Therefore, the further away a star is, the _more difficult it is_ to measure its parallax.

F. ESA’s Hipparcos satellite has used parallax to determine the distance of the closest _________ stars to the Sun. It had the ability to measure stellar shifts equivalent to the width of _________________________! G. ESA’s next parallax mission, Gaia, was launched Dec 19, 2013. It will determine the distance to the closest ________ stars. It will be able to measure a star’s position to the equivalent of the width of _________________________!! H. The parallax method is extremely important not only because it is the only direct method for determining stellar distances, but also because it ______________ for checking the validity of the other ________ distance measuring techniques.

F. ESA’s Hipparcos satellite has used parallax to determine the distance of the closest _100,000_ stars to the Sun. It had the ability to measure stellar shifts equivalent to the width of _a human hair seen at 20 km_! G. ESA’s next parallax mission, Gaia, was launched Dec 19, 2013. It will determine the distance to the closest ________ stars. It will be able to measure a star’s position to the equivalent of the width of _________________________!! H. The parallax method is extremely important not only because it is the only direct method for determining stellar distances, but also because it ______________ for checking the validity of the other ________ distance measuring techniques.

F. ESA’s Hipparcos satellite has used parallax to determine the distance of the closest _100,000_ stars to the Sun. It had the ability to measure stellar shifts equivalent to the width of _a human hair seen at 20 km_! G. ESA’s next parallax mission, Gaia, was launched Dec 19, 2013. It will determine the distance to the closest _1 billion_ stars. It will be able to measure a star’s position to the equivalent of the width of _a human hair seen at 1000 km_!! H. The parallax method is extremely important not only because it is the _______________ for determining stellar distances, but also because it ______________ for checking the validity of the other ________ distance measuring techniques.

F. ESA’s Hipparcos satellite has used parallax to determine the distance of the closest _100,000_ stars to the Sun. It had the ability to measure stellar shifts equivalent to the width of _a human hair seen at 20 km_! G. ESA’s next parallax mission, Gaia, was launched Dec 19, 2013. It will determine the distance to the closest _1 billion_ stars. It will be able to measure a star’s position to the equivalent of the width of _a human hair seen at 1000 km_!! H. The parallax method is extremely important not only because it is the only direct methodfor determining stellar distances, but also because it _forms the basis_ for checking the validity of the other _indirect_ distance measuring techniques.

II. Stellar Magnitudes A. The magnitude of a star is a description of how _______ a star is. B. The scale was initially set up by Norman Pogson in 1856 with a magnitude ___ given to the brightest star in the sky and a magnitude ___ being the dimmest star that could be seen ____ ____________. C. The apparent magnitude of a star is a measure of its brightness _________________. The brighter an object appears, the ______ the value of its magnitude. For example, ___________ ______ and __________________. D. The absolute magnitude of a star is a measure of its _______ _________. It is a measure of a star’s brightness from a fixed distance of __________________. Note that the absolute magnitude of a star is equal to the apparent magnitude if the observer is at a distance of 10 parsecs from the star.

II. Stellar Magnitudes A. The magnitude of a star is a description of how _bright_ a star is. B. The scale was initially set up by Norman Pogson in 1856 with a magnitude ___ given to the brightest star in the sky and a magnitude ___ being the dimmest star that could be seen ____ ____________. C. The apparent magnitude of a star is a measure of its brightness _________________. The brighter an object appears, the ______ the value of its magnitude. For example, ___________ ______ and __________________. D. The absolute magnitude of a star is a measure of its _______ _________. It is a measure of a star’s brightness from a fixed distance of __________________. Note that the absolute magnitude of a star is equal to the apparent magnitude if the observer is at a distance of 10 parsecs from the star.

II. Stellar Magnitudes A. The magnitude of a star is a description of how _bright_ a star is. B. The scale was initially set up by Norman Pogson in 1856 with a magnitude _1_ given to the brightest star in the sky and a magnitude _6_ being the dimmest star that could be seen _with the naked eye_. C. The apparent magnitude of a star is a measure of its brightness _________________. The brighter an object appears, the ______ the value of its magnitude. For example, ___________ ______ and __________________. D. The absolute magnitude of a star is a measure of its _______ _________. It is a measure of a star’s brightness from a fixed distance of __________________. Note that the absolute magnitude of a star is equal to the apparent magnitude if the observer is at a distance of 10 parsecs from the star.

II. Stellar Magnitudes A. The magnitude of a star is a description of how _bright_ a star is. B. The scale was initially set up by Norman Pogson in 1856 with a magnitude _1_ given to the brightest star in the sky and a magnitude _6_ being the dimmest star that could be seen _with the naked eye_. C. The apparent magnitude of a star is a measure of its brightness _as seen from Earth_. The brighter an object appears, the _lower_ the value of its magnitude. For example, _1 is brighter than 3_ and _-1 is brighter than 1_. D. The absolute magnitude of a star is a measure of its _______ _________. It is a measure of a star’s brightness from a fixed distance of __________________. Note that the absolute magnitude of a star is equal to the apparent magnitude if the observer is at a distance of 10 parsecs from the star.

II. Stellar Magnitudes A. The magnitude of a star is a description of how _bright_ a star is. B. The scale was initially set up by Norman Pogson in 1856 with a magnitude _1_ given to the brightest star in the sky and a magnitude _6_ being the dimmest star that could be seen _with the naked eye_. C. The apparent magnitude of a star is a measure of its brightness _as seen from Earth_. The brighter an object appears, the _lower_ the value of its magnitude. For example, _1 is brighter than 3_ and _-1 is brighter than 1_. D. The absolute magnitude of a star is a measure of its _intrinsic brightness_. It is a measure of a star’s brightness from a fixed distance of _10 parsecs (32.6 ly)_. Note that the absolute magnitude of a star is equal to the apparent magnitude if the observer is at a distance of 10 parsecs from the star.

E. The Hubble Space Telescope has observed stars with magnitudes down to ____ at visible wavelengths and the Keck telescopes have located similarly faint stars in the infrared with _________________. F. There is a _________ difference in brightness for stars that differ by a _____________. For example, a star of magnitude 1 is 100 times as bright as a star with magnitude 6. Hubble Space Telescope Keck Telescopes

E. The Hubble Space Telescope has observed stars with magnitudes down to _30_ at visible wavelengths and the Keck telescopes have located similarly faint stars in the infrared with _very long exposures_. F. There is a _________ difference in brightness for stars that differ by a _____________. For example, a star of magnitude 1 is 100 times as bright as a star with magnitude 6. Hubble Space Telescope Keck Telescopes

E. The Hubble Space Telescope has observed stars with magnitudes down to _30_ at visible wavelengths and the Keck telescopes have located similarly faint stars in the infrared with _very long exposures_. F. There is a _100 times_ difference in brightness for stars that differ by a _magnitude of 5_. For example, a star of magnitude 1 is 100 times as bright as a star with magnitude 6. Hubble Space Telescope Keck Telescopes

III. Spectral Classes • A. Stars are classified largely by their ___________________. This is precisely measured by observing their ____________ • ___________. • B. A star’s color and temperature is determined ______________ • _______. The more massive a star is, the _________________ it is. • C. Most stars are currently classified using the letters O, B, A, F, G, K and M, where O stars are the ________ and M stars are the _______. • D. The order of these letters can be remembered by this pneumonic: • _____________ • _____________ • _____________ • _____________ • _____________ • _____________ • _____________

III. Spectral Classes • A. Stars are classified largely by their _color and temperature_. This is precisely measured by observing their _spectra with a spectrograph_. • B. A star’s color and temperature is determined ______________ • _______. The more massive a star is, the _________________ it is. • C. Most stars are currently classified using the letters O, B, A, F, G, K and M, where O stars are the ________ and M stars are the _______. • D. The order of these letters can be remembered by this pneumonic: • _____________ • _____________ • _____________ • _____________ • _____________ • _____________ • _____________

III. Spectral Classes • A. Stars are classified largely by their _color and temperature_. This is precisely measured by observing their _spectra with a spectrograph_. • B. A star’s color and temperature is determined _almost entirely by its mass_. The more massive a star is, the _hotter and brighter_ it is. • C. Most stars are currently classified using the letters O, B, A, F, G, K and M, where O stars are the ________ and M stars are the _______. • D. The order of these letters can be remembered by this pneumonic: • _____________ • _____________ • _____________ • _____________ • _____________ • _____________ • _____________

III. Spectral Classes • A. Stars are classified largely by their _color and temperature_. This is precisely measured by observing their _spectra with a spectrograph_. • B. A star’s color and temperature is determined _almost entirely by its mass_. The more massive a star is, the _hotter and brighter_ it is. • C. Most stars are currently classified using the letters O, B, A, F, G, K and M, where O stars are the _hottest_ and M stars are the _coolest_. • D. The order of these letters can be remembered by this pneumonic: • _____________ • _____________ • _____________ • _____________ • _____________ • _____________ • _____________

III. Spectral Classes • A. Stars are classified largely by their _color and temperature_. This is precisely measured by observing their _spectra with a spectrograph_. • B. A star’s color and temperature is determined _almost entirely by its mass_. The more massive a star is, the _hotter and brighter_ it is. • C. Most stars are currently classified using the letters O, B, A, F, G, K and M, where O stars are the _hottest_ and M stars are the _coolest_. • D. The order of these letters can be remembered by this pneumonic: • _Oh,_________ • _Be__________ • _A___________ • _Fine_________ • _Girl/Guy______ • _Kiss_________ • _Me__________

E. General Trends: • O B A F G K M B A F G K M

IV. HR Diagrams A. HR Diagrams are to __________ as the _____________ ___________. B. The HR diagrams where developed by ________________ and __________________. C. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' ______ ____________________ versus their ______________ _________________. D. The HR diagrams represented a major step towards an understanding the _______________.

IV. HR Diagrams A. HR Diagrams are to _astronomy_ as the _Periodic Table is to chemistry_. B. The HR diagrams where developed by ________________ and __________________. C. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' ______ ____________________ versus their ______________ _________________. D. The HR diagrams represented a major step towards an understanding the _______________.

IV. HR Diagrams A. HR Diagrams are to _astronomy_ as the _Periodic Table is to chemistry_. B. The HR diagrams where developed by _EjnarHertzsprung_ and _Henry Norris Russel_. C. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' ______ ____________________ versus their ______________ _________________. D. The HR diagrams represented a major step towards an understanding the _______________.

IV. HR Diagrams A. HR Diagrams are to _astronomy_ as the _Periodic Table is to chemistry_. B. The HR diagrams where developed by _EjnarHertzsprung_ and _Henry Norris Russel_. C. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' _abolute magnitude (or luminosity)_ versus their _spectral type (or surface temperature)_. D. The HR diagrams represented a major step towards an understanding the _______________.

IV. HR Diagrams A. HR Diagrams are to _astronomy_ as the _Periodic Table is to chemistry_. B. The HR diagrams where developed by _EjnarHertzsprung_ and _Henry Norris Russel_. C. The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' _abolute magnitude (or luminosity)_ versus their _spectral type (or surface temperature)_. D. The HR diagrams represented a major step towards an understanding the _evolution of stars_.

Parallax, Magnitudes, Spectral Classes & HR Diagrams

Parallax, Magnitudes, Spectral Classes & HR Diagrams