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Scientists Discover New Super-Magnetic Star

Artwork by Davis Meltzer

 

A newly discovered star with an extremely strong magnetic field has caught the attention of scientists.  Located about 20,000 light-years from Earth, NGC1624-2 is the most magnetic massive star discovered by astronomers to date.

NGC1624-2 has about 35 times the mass of our sun and possesses a magnetic field nearly 20,000 times stronger.  Because of its distance scientists have been monitoring it with a telescope at the University of Texas’ McDonald Observatory, and they have determined that NGC1624-2 rotates very slowly – about 160 Earth days for a complete rotation compared with just 25 days for the sun.

Although smaller stars with stronger magnetic fields have been found, this is the first time a magnetic field of this intensity has been observed around a massive star.  “Magnetic fields of this strength are extremely rare,” said astronomer Gregg Wade.  He and his colleagues have detailed their findings in the Monthly Notices of the Royal Astronomical Society.  “To find such a strong field is very lucky.”

Why?  Because very little is understood about how magnetism affects the evolution of stars.  The more scientists learn about the subject, the better they can understand the structure of galaxies as a whole.

For all the latest science news, check out our twice-weekly news rundown, EarthCurrent.

 

Comments

  1. himadri shekhar howlader
    india
    October 10, 2012, 3:43 pm

    How do i trace the star which is mentioned in detail in the article as there are two stars are clearly visual, but i want to know which is the star has the id number is NGC 1624-2 ?

    my second question is it is mention that the star is 20,000 light-years far away. then how much time it took the shot of this picture.

  2. EMC2
    Raleigh, NC
    September 21, 2012, 10:03 am

    This paper presents a first observational investigation of the faint Of?p star NGC 1624-2, yielding important new constraints on its spectral and physical characteristics, rotation, magnetic field strength, X-ray emission and magnetospheric properties. Modelling the spectrum and spectral energy distribution, we conclude that NGC 1624-2 is a main-sequence star of mass M ≃ 30 M⊙, and infer an effective temperature of 35 ± 2 kK and log g = 4.0 ± 0.2. Based on an extensive time series of optical spectral observations we report significant variability of a large number of spectral lines, and infer a unique period of 157.99 ± 0.94 d which we interpret as the rotational period of the star. We report the detection of a very strong (5.35 ± 0.5 kG) longitudinal magnetic field 〈Bz〉, coupled with probable Zeeman splitting of the Stokes I profiles of metal lines confirming a surface field modulus 〈B〉 of 14 ± 1 kG, consistent with a surface dipole of polar strength ≳20 kG. This is the largest magnetic field ever detected in an O-type star, and the first report of Zeeman splitting of Stokes I profiles in such an object. We also report the detection of reversed Stokes V profiles associated with weak, high-excitation emission lines of O iii, which we propose may form in the close magnetosphere of the star. We analyse archival Chandra ACIS-I X-ray data, inferring a very hard spectrum with an X-ray efficiency of log Lx/Lbol = −6.4, a factor of 4 larger than the canonical value for O-type stars and comparable to that of the young magnetic O-type star θ1 Ori C and other Of?p stars. Finally, we examine the probable magnetospheric properties of the star, reporting in particular very strong magnetic confinement of the stellar wind, with η* ≃ 1.5 × 104, and a very large Alfvén radius, RAlf = 11.4 R*.

  3. John
    Otis, Oregon
    September 21, 2012, 5:44 am

    And how do they gauge this distance. A depth finder wont work that far out.

  4. Adam
    CO, USA
    September 18, 2012, 1:24 pm

    How do scientists detect and/or measure the magnetism of a star or anything that’s 20,000 light years away?