NGC 3603-C (HD 97950C) is a single-lined spectroscopic

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system located at the centre of the HD 97950 cluster in the

NGC 3603 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 (probably a super star cluster) HD 97950. ...

star-forming region Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

, about 25,000

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. The primary has spectral type WN6h and is 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, although several of them have since been resolved into more than one star. Star C was shown to be a binary, but its companion has not been observed. HD 97950C 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 A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. D ...

and the

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

is completely hidden. The surface fraction of hydrogen is still estimated to be 70%. The two component stars of NGC 3603-C circle each other every nine days. It is assumed that the secondary is sufficiently smaller and fainter than the primary not to affect the calculation of its physical properties. The mass is estimated to be and the luminosity over . Although the star is very young, around 1.5 million years old, it has already lost a considerable fraction of its initial mass. The initial mass is estimated to have been , meaning it has lost .

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NASA Image of the day
{{DEFAULTSORT:NGC 3603-C Carina (constellation) Wolf–Rayet stars NGC 3603 097950C 054948C Durchmusterung objects Spectroscopic binaries

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