Data source: ESA Gaia DR3
Radius in Action: Estimating the Volume of a Blue Giant in Cepheus
At the heart of stellar storytelling is a simple yet powerful idea: a star’s size can tell us how much space it occupies in the cosmos. In this article, we explore how radius data from Gaia DR3 translates into a tangible sense of volume for a remarkable blue giant located in the northern skies, near the constellation Cepheus. The subject of our discussion is Gaia DR3 2008024002628540160, a blazing star whose heat, brightness, and distance illuminate the scale of stellar rooms in the Milky Way.
Gaia DR3 2008024002628540160 presents a vivid example of how radius estimates—drawn from Gaia’s broad-band colors and stellar atmosphere models—inform our intuition about a star’s size. In Gaia DR3, the radius_gspphot value for this star is about 13.44 times the Sun’s radius. That single number unlocks a spectacular implication: the star’s volume is roughly proportional to the cube of its radius. If you imagine the Sun as a tiny sphere, this blue giant would cube that volume to become about 2.4 thousand times larger. In other words, its immediate “stowaway space” dwarfs the Sun by more than two thousand solar volumes. This is a reminder that stellar greatness often hides in plain sight inside a single Gaia data point.
The star’s temperature reinforces why it looks blue and how its volume relates to its luminosity. Gaia DR3 2008024002628540160 has a Teff_gspphot around 31,000 K—a scorching furnace by any standard. Such temperatures push the emitted spectrum toward the blue and violet end of the visible range, which is why this star appears as a blue-white beacon in photographs and catalogs. In the language of stellar classification, this is a hot B-type object, sitting near the upper-left corner of the Hertzsprung–Russell diagram where heat and gravity combine to yield luminous, compact giants.
The star sits at a distance of roughly 1,965 parsecs from Earth, translating to about 6,400 light-years. That distance places it well within the Milky Way’s disk, in the Cepheus region. Its sky coordinates—right ascension around 338.58 degrees and declination around +58.63 degrees—anchor it to the northern celestial hemisphere, near the traditional home of Cepheus, the King. Despite its brightness, the star’s apparent magnitude (phot_g_mean_mag) of about 12.20 means it is far too faint to see with the naked eye under ordinary sky conditions. Its glow requires a modest telescope or a long exposure to be appreciated, reminding us how many of the galaxy’s giants operate beyond the reach of casual stargazing.
Why does radius matter so much for understanding a star’s volume and its place in the cosmos? The simple geometric relation V = 4/3 π R^3 shows that small changes in radius translate into much larger changes in volume. For Gaia DR3 2008024002628540160, the radius of 13.44 R☉ means a volume about 2.4×10^3 times that of the Sun. This volumetric jump is not merely a curiosity; it ties directly into the star’s luminosity. With a high Teff, the star radiates a prodigious amount of energy, and its radius amplifies that energy output. In broad terms, L ∝ R^2 T^4, so a large radius combined with a blistering surface temperature produces a luminous giant blazing in the Cepheus region.
Gaia DR3 2008024002628540160 carries a piece of history encoded in its name and location. The enrichment summary describing this star paints a portrait of a hot, luminous giant whose color and size evoke royal energy and protective symbolism. Its celestial home in Cepheus—the mythic king of Aethiopia and husband of Cassiopeia, father of Andromeda—adds a human layer to the science: even among the vast, silent stars, stories anchor our sense of scale and place. In this view, a blue-white giant hundreds of light-years away becomes a reminder of the extraordinary diversity contained within our Milky Way.
“Cepheus, king of Aethiopia and husband of Cassiopeia, father of Andromeda, was placed among the stars after the tale of Andromeda's rescue from Cetus.”
When we approach radius_gspphot as a tool for cosmic measurement, we gain a practical pathway to translate numerical results into physical intuition. The radius gives us a doorway into volume, the magnitude hints at how far we are and how bright the star appears from Earth, and the temperature shows us the star’s color and energy. Taken together, these data points allow both professional astronomers and curious stargazers to appreciate the scale of a blue giant in Cepheus without requiring a telescope the size of a small observatory dome.
For readers who enjoy connecting data with the broader sky, Gaia DR3 2008024002628540160 sits in a neighborhood of the Milky Way where stellar newborns and older giants mingle. The cataloged distance places it beyond our immediate orange-hued neighborhood of the Sun, inviting us to imagine the light that began its journey long before our human history began to unfold. In practical terms, the star’s volume — about 2,400 times the Sun’s — is a vivid reminder of how much space a single star can command in the vastness of our galaxy.
If you’d like to explore similar data yourself, Gaia’s DR3 catalog offers a treasure trove of radius estimates, temperatures, and distances that illuminate the architecture of our galaxy.
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.