NGC 3603-A1

For the general A1 star type, see Stellar classification.

A1

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Carina
Right ascension	11h 15m 09.1s
Declination	-61° 16′ 17″
Astrometry
Spectral type	WN6h+WN6:h
Apparent magnitude (V)	9.1
Distance	20.000 Ly
Binary orbit
Period (P)	3.77 [1] days
Eccentricity (e)	0[1]
Inclination (i)	71° [1]
Details
Mass	116.0 (primary)[1] / 89.0 (b)[1] M☉
Radius	(primary)[1] / ? (b)[1] R☉
Luminosity	100,000 (system) L☉
Temperature	? (primary)[1] K

NGC 3603-A1 is a massive, double-eclipsing binary star system located in NGC 3603, about 20,000 light years from Earth. Its two component stars circle each other every 3.77 days. The mass of NGC 3603-A1a is 116 ± 31 solar masses and 89 ± 16 solar masses for NGC 3603-A1b.^[2] This makes them the two most massive stars directly measured so far, i.e. their masses have been determined (using Keplerian orbits), and not estimated. Both show an emission-line spectrum (spectral type WN6h). The stars were identified and their masses calculated by a team from the Université de Montréal.

References

1. ^ ^{a b c d e f g h} The very massive binary NGC 3603-A1, O. Schnurr, J. Casoli, A.-N. Chené, A.F.J. Moffat, N. St-Louis, Monthly Notices of the Royal Astronomical Society: Letters 389, #1 (July 30, 2008), pp. L38–L42.
2. ^ Daily Mail (London), "Pictured: The cosmic factory that created the largest known star in our galaxy", Claire Bates, 4 February 2010 (accessed 4 February 2010)

External links

• Space Daily
• Sky & Telescope : The Most Massive Star Yet?
• Astronomy : The Most Massive Star