29 Persei
29 Persei
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29 Persei
Edmonton, Alberta, Canada
2018-Oct-18
Exposures: RGB 26/26/26 x 2m = 2h 36m
Processing: SGP,MaximDL,Gimp
Telescope: CFF132,STF-8300M,GM1000
Guider: LE80,LSX2,GSO2X
29 Persei is the bright star in the middle of the image.
This image centers on 29 Persei, a moderately bright blue star in Perseus. The other bright star in this image is 31 Persei and it is the blue-white star below and to the left of 29 Perseus. The two other moderately bright stars in the field are HD 20344 (top) and HD 20282 (center right). At the bottom of this page is an annotated image identifying the locations of all these stars, along some comments regarding their comparable stellar properties.

29 Persei
29 Persei is a blue-white star that has a spectral type of B3V. This means it is a B-type main sequence star, and it is several times larger than our sun. B type stars are blue in color, and are quite bright.

The visible magnitude of 29 Persei is 5.16 so it is visible from most locations without needing binoculars or a telescope.

B type stars are known for their prominent helium lines that appear in their spectral analysis. 29 Persei is no exception and it was included in the 1926 Astrophysical Journal article titled Radial velocities of 368 helium stars (Frost, E.B., Barrett S.B., and Struve O.)

31 Persei
The blue star to the lower left of 29 Persei is 31 Persei, a B5V spectral type star with a visual magnitude of 5.03.

55 Persei is similar, but not identical to 29 Persei. Of the two, 29 Persei is the larger and hotter. But they are similar enough, and are close enough together in space that we observe them as having very nearly the same brightness and color.

This star was also included in the heluim star article listed above, and both stars are also part of a study done in 1950 called The moving cluster in Perseus (Roman N.G. and Morgan W.W.).

The sky around 29 Persei
Besides 29 and 55 Persei, there are two other moderately bright stars in this field as well.

One of these stars is found near the top of the image. This is HD 20344, an A0 type which is a common white or blue-white main sequence star. The star is only magnitude 8.02 which puts it out of visual range for most observers. It it easily seen in most telescopes.

The other moderately bright blue star near 29 Persei is HD 20282. This is also an A0 spectral type and it is similar to HD 20344 in brightness at a magnitude of 7.51. This means it may be visible unaided to some observers from a dark site, but it is very near the edge of human visual perception.

Both HD 20344 and HD 20282 are A type main sequence stars. These two are similarly blue-white colored, and they look a lot like the B type stars in this image do. But the A type stars are clearly less bright, and they also show a little less blue than the brighter B types do.

All four of these of these stars are roughly the same distance from us in space. And from this image, we can see that the two B type stars, 29 and 31 Persei, are clearly brighter and a bit bluer than the two A type stars shown above them. This is consistent with their star classifications since B types are large, hot and blue stars that are more luminous than most other stars except the rare O types.

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