Star profile
Tau Herculis
Hot blue starWhat is Tau Herculis
τ Herculis is a blue-white subgiant 307 light-years away, set in the body of the celestial Kneeler. Its B5 IV spectrum places it among the hot, massive stars, with nearly five solar masses and 700 times the Sun's brightness. Though seemingly still, its light flickers slightly: a young variable not yet committed to its fate.
Where it is and when to see it
Tau Herculis lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is May, when it culminates around midnight.
- From London it never sets and culminates about 85° up.
- From New York it culminates about 84° above the horizon.
- From Sydney it culminates about 10° above the horizon.
It can be seen from anywhere north of 44° S.
It ranks no. 14 in brightness among the 136 stars of Hercules in our catalogue. To find it, start from Kornephoros, the brightest: it lies about 25° away (a fist at arm's length covers about 10°).
The light you see today left it about 310 years ago.
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Astronomical data for Tau Herculis
- Constellation
- Hercules
- Apparent magnitude
- 3.91
- Distance
- 307.4 light years
- Coordinates (J2000)
- RA 244.935° · Dec 46.313°
- Catalogue
- HIP 79992 · HD 147394
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Other stars in Hercules
Hercules has 136 stars in Stelvia's catalogue. Here are a few of them.
- KornephorosBeta Herculis2.78
- RasalgethiAlpha 1 Herculis2.78
- Zeta Herculis2.81
- Omicron Herculis3.84
- 109 Herculis3.85
- Theta Herculis3.86
- Epsilon Herculis3.92
- Rho Herculis4.15