Onekilopars QnA
Which of the following is most like the rotation of stars in the disk of the Milky Way?
Which of the following is most like the rotation of stars in the disk of the Milky Way? Cars moving at a constant speed on a circular race track. What observations suggest the mass of the Galaxy goes much farther out than its visible disk? The rotation curve of the outermost portions of the disc.
What does RR mean in RR Lyrae?
any of the very regular, short-period, pulsating variable stars having periods between 1.5 and 29 hours. Word origin. RR, astronomical code designation of tenth variable + Lyrae, gen. What color are RR Lyrae stars? Visual Facts Primary Name RR Lyrae The Sun Star Type based on Spectral Type Variable Star Main Sequence Star Colour Blue Yellow (Atmosphere) / White (In Space) Galaxy Milky Way Milky Way Constellation Lyra N/A 28 more rows
Why are RR Lyrae stars useful distance indicators?
RR Lyrae star, any of a group of old giant stars of the class called pulsating variables (see variable star) that pulsate with periods of about 0.2?1 day. The intrinsic luminosities of RR Lyrae stars are relatively well-determined, which makes them useful as distance indicators. Why are RR Lyrae variables not used to find distances to distant galaxies? Why are RR-Lyrae variables not used to find distances to distant galaxies? They are not bright enough to be seen at large distances. Type Ia supernovae are frequently used as standard candles for the measurement of distances to galaxies, but they are not all equally luminous.
Keeping this in consideration, how do astronomers measure the distance to rr lyrae stars?
The period of pulsation of an RR Lyrae variable depends on its mass, luminosity and temperature, while the difference between the measured luminosity and the actual luminosity allows its distance to be determined via the inverse-square law. You can also ask what important measurement did rr lyrae variables allow astronomers to get? RR Lyrae's brightness (between 7th and 8th magnitude) made it bright enough to observe spectroscopically in such a way that the changes in its spectrum could be traced throughout its cycle of variability. This enabled astronomers to measure changes in spectral type, as well as to detect the presence of emission lines.
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