I was looking to Scorpio the other day, and noticed that the last star in the tail (the telson's tip) -- known as Upsilon Scorpii, υ Scorpii, or Lesath -- seemed yet more red than the "heart" of the scorpion -- Antares or Alpha Scorpii. Was it that I was drunk, or some kind of sky pollution? (Actually, a friend confirmed it was red, and she seemed sober than me.) Or is it, indeed, red? I couldn't find any information on-line. I saw this database, but don't know how to find a star by its name, or if they have information about the color.
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$\begingroup$ en.wikipedia.org/wiki/Upsilon_Scorpii B-V=-0.22 It is a blue/white star. $\endgroup$ – ProfRob Oct 11 '17 at 11:19
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$\begingroup$ @RobJeffries The red color was confirmed by at least another person (see my edit). Is there any site like a on-line telescope? $\endgroup$ – Rodrigo Oct 11 '17 at 11:28
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$\begingroup$ Rodrigo, what you saw and what the star is are two different things. The star is blue/white. When you look at it through the atmosphere, especially low to the horizon, then it may appear to be something else. You asked a question - you have the answer. $\endgroup$ – ProfRob Oct 11 '17 at 11:31
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$\begingroup$ @RobJeffries δ Sco, β Sco and π Sco were almost behind some not very close trees, so somewhat close to the horizon. Therefore υ Sco wasn't so low. It was the first time that I noticed it look SO red, and this called my attention. I would like if it could be confirmed by someone else (or at least discover why it appeared so red). $\endgroup$ – Rodrigo Oct 11 '17 at 11:43
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$\begingroup$ Actually it is very close to lambda Sco which is a brighter star. But just as blue/white. $\endgroup$ – ProfRob Oct 11 '17 at 11:50
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I don't know what could cause Upsilon Scorpii to appear red as it is not noted as being a highly variable star. It's spectral type is B2, which implies it would be blue/white in colour. If you know the spectral type of a star, which many stellar databases will note, you can work out its colour from this.
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$\begingroup$ The red color was confirmed by at least another person (see my edit). Is there any site like a on-line telescope? I got intrigued about this. $\endgroup$ – Rodrigo Oct 11 '17 at 11:28
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$\begingroup$ Aladin Lite shows Upsilon Scorpii as blue in the DSS2 survey. $\endgroup$ – user21 Oct 11 '17 at 16:07
