Positioned in the southern hemisphere, Cetus, the Sea Monster, is a sprawling constellation best viewed in late autumn. Among Cetus’ notable stars lies the binary star Struve 274, a quaint pair of white stars that are fairly easy to view in any modest backyard scope.
Struve 274’s stars are close in magnitude and color. The primary star shines at magnitude +7.5, while the nearby secondary is slightly dimmer at magnitude +7.6. The stars lie a healthy 13.7 arcseconds apart, making them an easy binary target for amateur astronomers.
Regarding their stellar classification, both stars are “Am” stars. This particular type of A-type star features strong absorption lines of metals and is often found in close binary systems. Also, “Am” binary stars rotate slower than typical A-type stars because of tidal braking. In essence, tidal braking acts as a cosmic brake, gradually sapping the rotational energy of the stars and causing them to synchronize their rotation with the orbital period. This synchronization often leads to one side of each star permanently facing its companion, a phenomenon known as tidal locking. The brightest star in the sky, Sirius, is an Am star.
My Observations
| Date | December 16, 2023 |
| Time | 7:38 p.m. |
| Location | Seattle, WA |
| Magnification | 169x |
| Scope | Meade 8″ SCT |
| Eyepiece | 12mm |
| Seeing | Average |
| Transparency | Average |
I’m glad to return to Cetus a year after I first recorded the attractive double star 66 Ceti. Many of the taller Douglas Fir trees near the home block a full of Cetus, so I need to duck in and out of the constellation between branches!
Struve 274 is a typical binary star system that displays two matching stars, which I can easily discern through my 12mm eyepiece. At first glance, the stars appear to have a light blue hue, but upon longer observation, I notice they are actually off-white in color.
Key Stats
| Constellation | Cetus |
| Best Viewing | Late Autumn |
| Visual Magnitude | +7.5 | +7.6 |
| Separation | 13.7″ |
| Position Angle | 220° |
| Distance | 163 ly |
| My Viewing Grade | B |
| Designations | STF 274, HD 15695, SAO 110591, HIP 11737 |
Sources and Notes
The banner illustration was created by the European Southern Observatory (ESO) and is under the Creative Commons Attribution 4.0 International License. Per ESO agreement: Here is the original image on the ESO website.
02315+0106 STF 274 AB (HD 15695). WDS 02315+0106 STF 274 AB (HD 15695). (n.d.). https://www.stelledoppie.it/index2.php?iddoppia=9142
The Garden Astronomer 
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