HR 1040 CAM (HR 1040 Camelopardalis). Massive stars (indeed probably all stars) tend to be born in groups within the cold dusty clouds of interstellar space. They burn out fast and consequently don't get very far from their birthplaces, and thus form expanding "OB associations" named after the spectral classes of the hot dwarfs that occupy them. Some are tight and compact, while others, like the Cam OB1 association (mostly in the far northern constellation, Camelopardalis, the Giraffe), spread rather widely. Cam OB1 is dominated visually by the fourth magnitude (4.21) class B (B9) bright supergiant HR 1035 and just-barely fifth magnitude (4.54) HR 1040 (a similar A0 bright supergiant), the designation referring to their listings in the "Bright Star Catalogue." Oddly, ranking numbers 2 and 5 in brightness within the constellation, they carry neither Greek letters nor Flamsteed numbers. HR 1035 (which is only about a degree north of HR 1040) is the brighter because there is less absorbing interstellar dust in the way. Were there none, HR 1040 would appear one and three-quarter magnitudes brighter and shine at magnitude 2.78, reversing their roles. The higher dust absorption is probably because of HR 1040's greater distance of 2510 light years, as opposed to 1035's distance of 1940 l-y. Such distances, though, are fraught with uncertainties. HR 1040 could statistically be as near as 1750 l-y or as far as 4400 l-y. HR 1035 has a similar problem. All we can do is adopt the star_intro.html#brightness">parallax measure and hope for the best.

HR1035 HR 1035 at left and HR 1040 at right are both related to dusty interstellar clouds that reflect or, more accurately, scatter their starlight. The scattering process is much more efficient toward shorter spectral wavelengths, which gives the "reflection nebulae" a bluish color, not seen here in this early black and white photograph. (Palomer Sky Survey.)

Given a temperature of 10,540 Kelvin there is only a little ultraviolet radiation to add. With the nominal distance we then find a huge luminosity of 51,000 times that of the Sun, 70 percent more than 1035's and similar to that of Deneb's, whose slight variable nature it mimics (and is thusly also called CE Cam), the star among the great ones of the local Galaxy. Luminosity and temperature give a radius of 68 times that of the Sun, about 80 percent the size of Mercury's orbit. Theory yields a mass of 15 times that of the Sun if the star is in transition to the red supergiant state with a dead helium core or maybe 13.5 solar masses if it is in a quiet state of core helium fusion. Unlike HR 1035, HR 1040 appears all alone, with no binary companion. Both stars are within or near dusty clouds that reflect, or scatter, their tremendous light. HR 1040 seems to be buried in such a "reflection nebula" (the most famed of which surrounds the Pleiades) that is roughly two light years across. The most amazing thing perhaps is that such stars are nearly lost within obscure constellations that have practically no "outline" to speak of, figures one would be hard-pressed to find. And there are others. Also belonging to Cam OB1 is the sixth magnitude (5.79) class A0 bright supergiant HR 964, the sixth magnitude (5.76) K4 lesser supergiant HR 1112, and the sixth magnitude (5.77) B0 giant HR 1417, better known perhaps as 1 Cam (at least one star got a Flamsteed number), after which we run out of naked eye stars.

Written byJim Kaler 1/16/15. Return to STARS.