1 CAM (1 Camelopardalis). "Number 1" makes the star
seem impressive, Unfortunately, the brightest star in dim Camelopardalis (the Giraffe), Beta Cam, is only fourth magnitude, while 1
Cam shines at but fifth magnitude (5.43). "Number 1" is actually a Flamsteed number that refers to
the westernmost modestly bright star within the constellation, not brightness itself. Dim the
Giraffe might be, it holds a plethora of mighty stars, 1 Cam easily
included among their number. A first look reveals it to be (from Smythe
and Chambers) "A neat double....nearly in mid-distance
between Alpha Persei and Delta Aurigae, A 7 1/2 white, B 8 1/2
sapphire blue." In reality they both are blue-white, a sixth magnitude
(5.78) Class B (B0) giant
coupled to a seventh magnitude 6.82 class B0 subgiant-
dwarf separated by 10.4 seconds of arc, making it an easy
telescopic object. The problem is that we don't know how far away it
is. The star is too far for parallax, and because of the
inevitable errors, the parallax actually comes out negative. All we
can do is to get the visual magnitudes from the spectral classes as
derived from other stars in the HR diagram of magnitude vs. class
(respectively -4.5 and -4.0)and compare them to the observed
magnitudes after correction for dimming by interstellar dust (a whopping 1.52
magnitudes). We then get 2970 and 3830 light years for 1 Cam A and
B for an average of 3400 light years. In support, 1 Cam by odd
coincidence belongs to the Cam OB I association of hot blue massive
stars ("associations" groups of stars formed out of the same molecular
clouds but unlike clusters are gravitationally unbound, such that the
members gradually separate). Broad studies of Cam OB I place it 3300
light years away: not a bad fit! The temperatures are essentially
unknown. From the spectral class we'll adopt 27,000 K, which gives the
amount of ultraviolet radiation to be added to the visual and thus gives
luminosities of 55,000 and 35,000 Suns, radii
of 10.7 and 8.5 times that of the Sun, and masses of 18 and 16 Suns,
almost assuring that both will blow up as supernovae in the
not-too-distant future, especially since they are too far apart (at
least 10,800 Astronomical Units) to affect each other during
supergiant evolution. But are they really a pair? Over the past two
centuries they have changed their separation by a second of arc. Given
their physical separation, which from Kepler's Laws gives an orbital
period of at least 190,000 years, they may not be bound at all, just
related through their membership in the association and like all the
other hot stars are slowly drifting apart. A twelfth magnitude star
hovers in the area 150 seconds from the inner pair, but it is probably
just in the line of sight. Oddly, 1 Cam A is spinning with a projected
equatorial velocity of 280 kilometers per second (giving it a
rotational period of under two days), whereas 1 Cam B is hardly rotating
at all, the velocity too low to be measured. Finally 1 Cam A had the
reputation of being a rapidly chattering Beta
Cephei-type variable. Alas, the distinction has been withdrawn.
If there is a moral, it's don't bet the quality of the stars on the
basis of the dimness of constellation.
Written byJim Kaler 12/02/16. Return to STARS.