Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Carina |
Right ascension | 11h 15m 07.305s [1] |
Declination | −61° 15′ 38.43″ [1] |
Apparent magnitude (V) | 11.18 [1] |
Characteristics | |
Spectral type | WN6h+WN6h [2] |
B−V color index | 1.03 [1] |
Variable type | EA [3] |
Astrometry | |
Proper motion (μ) | RA: 2.4 [4] mas/yr Dec.: 2.8 [4] mas/yr |
Distance | 7,600 [2] pc |
Absolute magnitude (MV) | −8.13 [2] |
Orbit [3] | |
Primary | A1a |
Companion | A2b |
Period (P) | 3.7724 days |
Eccentricity (e) | 0 |
Inclination (i) | 71° |
Semi-amplitude (K1) (primary) | 330 ± 20 km/s |
Semi-amplitude (K2) (secondary) | 433 ± 53 km/s |
Details | |
A1a | |
Mass | 120 [2] M☉ |
Radius | 29 [2] R☉ |
Luminosity | 2,500,000 [2] L☉ |
Temperature | 42,000 [2] K |
Age | 1.5 [2] Myr |
A1b | |
Mass | 92 [2] M☉ |
Radius | 26 [2] R☉ |
Luminosity | 1,500,000 [2] L☉ |
Temperature | 40,000 [2] K |
Age | 1.5 [2] Myr |
Other designations | |
Database references | |
SIMBAD | data |
NGC 3603-A1 (HD 97950A1) is a double-eclipsing binary star system located at the centre of the HD 97950 cluster in the NGC 3603 star-forming region, about 25,000 light years from Earth. Both stars are of spectral type WN6h and among the most luminous and most massive known.
HD 97950 was catalogued as a star, but was known to be a dense cluster or close multiple star. In 1926, the six brightest members were given letters from A to F, [5] although several of them have since been resolved into more than one star. [6] Star A was first resolved into three components using speckle interferometry, although they can now be directly imaged using space-based or adaptive optics. [1] Component A1 was finally determined to be a spectroscopic binary. [7]
The two component stars of NGC 3603-A1 circle each other every 3.77 days, and show brightness variations of about 0.3 magnitudes due to eclipses. The stars orbit very close to each other, separated by barely their own diameters and at or near to filling their roche lobes. [7]
The masses of A1a and A1b determined from the orbital parameters are 116 ± 31 M☉ and 89 ± 16 M☉respectively. [3] This makes them the two most massive stars directly measured, i.e. with their masses determined (using Keplerian orbits), and not estimated from models. The masses estimated from analysis of the physical properties are slightly higher at 120 M☉ and 92 M☉.
Each component is a Wolf-Rayet (WR) star, with spectra dominated by strong broadened emission lines. Type WN6 indicates that ionised nitrogen lines are strong in comparison to ionised carbon lines, and the suffix h indicates that hydrogen is also seen in the spectrum. This type of WR star is not the classical stripped helium-burning aged star, but a young highly luminous object with CNO cycle fusion products showing at the surface due to strong conventional and rotational mixing, and high mass loss rates from the atmosphere. The emission lines are generated in the stellar wind and the photosphere is completely hidden. The surface fraction of hydrogen is still estimated to be 60-70%. [2]
Although the stars are very young, around 1.5 million years old, they have already lost a considerable fraction of their initial masses. The initial masses are estimated to have been 148 M☉ and 106 M☉, meaning they have lost 28 M☉ and 14 M☉ respectively. [2]
NGC 3603 is a nebula situated in the Carina–Sagittarius Arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive H II region containing a very compact open cluster HD 97950.
Sher 25 is a blue supergiant star in the constellation Carina, located approximately 25,000 light years from the Sun in the H II region NGC 3603 of the Milky Way. It is a spectral type B1Iab star with an apparent magnitude of 12.2. Its initial main sequence mass is calculated at 60 times the mass of the Sun, but a star of this type will have already lost a substantial fraction of that mass. It is unclear whether Sher 25 has been through a red supergiant phase or has just evolved from the main sequence, so the current mass is very uncertain.
R136 is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of the Tarantula Nebula in the Large Magellanic Cloud. When originally named it was an unresolved stellar object but is now known to include 72 class O and Wolf–Rayet stars within 5 parsecs of the centre of the cluster. The extreme number and concentration of young massive stars in this part of the LMC qualifies it as a starburst region.
HD 97950, is a multiple star system and part of a super star cluster within the NGC 3603 H II region. It was catalogued as a single star although it was always known to be a compact cluster. It is now resolved into a massive multiple star at the centre of one of the densest clusters in the galaxy.
HD 5980 is a multiple star system on the outskirts of NGC 346 in the Small Magellanic Cloud (SMC) and is one of the brightest stars in the SMC.
AB7, also known as SMC WR7, is a binary star in the Small Magellanic Cloud. A Wolf–Rayet star and a supergiant companion of spectral type O orbit in a period of 19.56 days. The system is surrounded by a ring-shaped nebula known as a bubble nebula.
9 Sagittarii is a massive binary star in the constellation Sagittarius. It has an apparent magnitude of 5.97. Both components are highly luminous O-type main-sequence stars.
NGC 371, also called Hodge 53, is an open cluster 200,000 light-years away located in the Small Magellanic Cloud in Tucana constellation.
R136a2 is a Wolf-Rayet star residing near the center of the R136, the central concentration of stars of the large NGC 2070 open cluster in the Tarantula Nebula, a massive H II region in the Large Magellanic Cloud which is a nearby satellite galaxy of the Milky Way. It has one of the highest confirmed masses and luminosities of any known star, at about 151 M☉ and 3.5 million L☉ respectively.
R136c is a star located in R136, a tight knot of stars at the centre of NGC 2070, an open cluster weighing 450,000 solar masses and containing 10,000 stars. At 142 M☉ and 3.8 million L☉, it is the one of the most massive stars known and one of the most luminous, along with being one of the hottest, at over 40,000 K. It was first resolved and named by Feitzinger in 1980, along with R136a and R136b.
HD 38282 is a massive spectroscopic binary star in the Tarantula Nebula, consisting of two hydrogen-rich Wolf-Rayet stars.
NGC 3603-B is a Wolf-Rayet star located at the centre of the HD 97950 cluster in the NGC 3603 star-forming region, about 25,000 light years from Earth. It has the spectral type WN6h and is among the most luminous and most massive stars known.
NGC 3603-C is a single-lined spectroscopic binary star system located at the centre of the HD 97950 cluster in the NGC 3603 star-forming region, about 25,000 light years from Earth. The primary has spectral type WN6h and is among the most luminous and most massive known.
Melnick 34, also called BAT99-116, is a binary Wolf–Rayet star near R136 in the 30 Doradus complex in the Large Magellanic Cloud. Both components are amongst the most massive and most luminous stars known, and the system is the most massive known binary system.
WR 42e is a Wolf–Rayet star in the massive H II region NGC 3603 in the constellation of the Carina. It is around 25,000 light-years or 7,600 parsec from the Sun. WR 42e is one of the most massive and most luminous stars known.
CD Crucis, also known as HD 311884, is an eclipsing binary star system in the constellation Crux. It is around 14,000 light years away near the faint open cluster Hogg 15. The binary contains a Wolf–Rayet star and is also known as WR 47.
HD 151932, also known as WR 78, is a Wolf-Rayet star located in the constellation Scorpius, close to the galactic plane. Its distance is around 1,300 parsecs away from the Earth. Despite being a blue-colored Wolf-Rayet star, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands. HD 151932 lies about 22′ west of the open cluster NGC 6231, the center of the OB association Scorpius OB1; it is not clear whether it is a part of the association or not. With an apparent magnitude of about 6.5, it is one of the few Wolf-Rayet stars that can be seen with the naked eye.
MTT 68 is a multiple star system located on the outskirts of the HD 97950 cluster in the NGC 3603 star-forming region, about 25,000 light years from Earth. It contains a rare example of an O2If* star which is one of the most luminous and most massive known.