Data source: ESA Gaia DR3
A blue-hot giant in Cassiopeia and the light it sheds
In the northern reaches of Cassiopeia, a blue-white beacon lights up the sky, catalogued by Gaia’s second data release. The star’s official designation in Gaia DR3 is Gaia DR3 511313902386078976. With a striking combination of extreme temperature and a compact stellar radius, this hot giant offers a vivid example of how massive stars illuminate the cosmos even when they lie thousands of light-years away. The star’s precise position is around right ascension 27.5138 degrees and declination 61.5731 degrees, placing it well within the familiar W-shaped constellation that guides northern observers through autumn nights. Its measured distance, about 2,946 parsecs, translates to roughly 9,600 light-years from our Sun, a scale that makes its brightness and color all the more remarkable.
The apparent brightness, as recorded in Gaia’s G-band, is modest: phot_g_mean_mag ≈ 11.33. In practical terms, that means you’d need a telescope to glimpse it with any clarity; it’s far shy of naked-eye visibility (the naked-eye limit is around magnitude 6 under dark skies). Yet the star’s intrinsic power becomes clear when we translate its temperature and radius into luminosity. Gaia DR3 511313902386078976 shows a surface temperature around 36,301 K and a radius of about 5.21 solar radii. Those numbers tell a story of a stellar engine humming far more intensely than the Sun, even though the surface area isn’t dramatically larger than our star’s. The contrast between extreme temperature and moderate radius yields a luminosity tens of thousands of times greater than the Sun’s, a hallmark of blue-hot giants in the Milky Way’s crowded spiral arms and workaday star-forming regions.
What these numbers reveal about color, temperature, and light
Temperature is the most direct signpost of a star’s color. With Teff around 36,300 K, this star should blaze a blue-white hue—a characteristic of early-B-type giants and subgiants. Such temperatures push the peak of the emitted spectrum far into the ultraviolet, which is why even a relatively modest radius translates into extraordinary luminosity. The Gaia color indices offer additional nuance: phot_bp_mean_mag ≈ 11.66 and phot_rp_mean_mag ≈ 10.80 yield a BP−RP color of roughly +0.86. In a purely a photometric sense, that value would imply a redder color, which seems at odds with the extreme blue temperature. The likely reconciliation is that interstellar dust, line-of-sight extinction, or calibration nuances in DR3 can redden observed colors for very hot, distant stars. The lesson for observers is to read color as a guide rather than a strict verdict, especially in the crowded, dusty disk of our Galaxy.
Using the simple but powerful luminosity relationship L ∝ R²T⁴ (where R is the star’s radius and T its surface temperature, with the Sun as the reference), we can estimate Gaia DR3 511313902386078976’s luminosity. Plugging in R ≈ 5.21 R⊙ and T ≈ 36,301 K, we find L/L⊙ ≈ (5.21)² × (36,301/5,772)⁴ ≈ 27.1 × 1,560 ≈ 42,000. In round numbers, this star shines about 40,000 times brighter than the Sun. Such luminosity is a telling sign of a star that has moved beyond a quiet, sun-like life stage and now radiates with the power of a blue-hot giant in the Milky Way’s tapestry.
A star in Cassiopeia: location, distance, and context
Situated in Cassiopeia, this star sits in a rich stellar neighborhood. Its distance—nearly 3 kiloparsecs—places it well into the disk of our galaxy, well beyond the immediate solar neighborhood. Even at that distance, Gaia’s data allow us to infer its true brightness and physical scale. For observers, the combination of location and color makes it a vivid example of why Cassiopeia remains a favorite target for northern observers and astrophysicists alike: a region where hot, luminous stars anchor our understanding of stellar evolution in a relatively nearby galactic locale.
“In Greek myth, Cassiopeia boasted of her beauty and offended Poseidon. As punishment, she sits on a celestial throne in the northern sky, sometimes depicted upside down.”
The enrichment summary from the Gaia DR3 record for Gaia DR3 511313902386078976 captures the blend of precision and poetry: a hot, luminous star with Teff ≈ 36,000 K and a radius near 5.2 solar radii shines from Cassiopeia high in the northern sky, weaving precise stellar physics with the mythic tale of pride and its consequences. It is a living reminder that the cosmos and our mythic imagination are often synchronized on the same celestial stage.
Why this star stands out for study and wonder
A Teff around 36,000 K marks a blue-white glow that hints at a young, energetic phase of stellar evolution and a spectrum rich in high-energy photons. A radius of about 5.2 R⊙ yielding tens of thousands of times solar luminosity illustrates how a star can be dazzlingly bright even without an extremely large surface area. At nearly 3 kpc, the star sits well into the Milky Way’s disk, reminding us how Gaia’s photometry reaches across thousands of light-years to land precise physical inferences here on Earth. Its Cassiopeia locale connects it to a constellation famed for guiding stargazers and inspiring myths that blend culture with astronomy.
For curious readers who enjoy a closer look, this star serves as a perfect example of how Gaia DR3 data can translate distant light into tangible properties—color, temperature, size, and brightness—so we can tell a detailed story about stellar life cycles and the architecture of our Galaxy. And it invites us to look up with a renewed sense of wonder, recognizing that in Cassiopeia, every point of blue light carries a tale of heat, luminosity, and cosmic history.
Neon Tough Phone Case (Impact Resistant, Glossy)
This star, though unnamed in human records, is one among billions charted by ESA’s Gaia mission.
Each article in this collection brings visibility to the silent majority of our galaxy — stars known only by their light.