An artist's illustration depicts the interior of a low-mass star, such
as the one seen in an X-ray image from Chandra in the image below. Such
stars have different interior structures than our Sun. A new study
looking at four of these low-mass stars shows the strength of magnetic
fields of these stars - which is revealed by the amount of X-ray
emission from the stars - are similar to those of more massive ones like
the Sun. This discovery may have profound implications for
understanding how the magnetic field in the Sun and stars like it are
generated.
(Credit: NASA/CXC/M.Weiss)
Magnetic fields on the Sun and stars like it are responsible for much of
their behavior, including the generation of powerful storms that can
produce spectacular auroras
on Earth, damage electrical power systems, knock out communications
satellites, and affect astronauts in space. As discussed in our latest press release, new research relying on data from NASA's Chandra X-ray Observatory is helping astronomers better understand how these magnetic fields are produced.
By comparing the X-ray emission,
an excellent indicator of a star's magnetic field strength, between
low-mass stars and the Sun, a pair of astronomers was able to find an
important clue about how stellar magnetic fields are generated.
The Sun and stars with approximately the same mass have a divided
internal structure with an inner radiation zone (energy moves outward)
and an outer convection zone (the energy circulates). Stars with
significantly lower masses, however, do not have such a differentiated
structure. Instead, the process of convection is dominant throughout the
star, which is depicted in the artist's illustration in the main panel of the graphic.
The researchers in this latest study looked at four low-mass stars - two with Chandra and two with archival data from the ROSAT satellite
- and found their X-ray emission was similar to that of stars like the
Sun. (The inset in the graphic shows Chandra's data of one of these
low-mass stars, GJ 3253).
This result was surprising because many scientists think the boundary
between the radiation and convection zones in the Sun and Sun-like stars
contributes to the strength of its magnetic field. If stars without
such a boundary have relatively powerful magnetic fields, then this
theory may need to be re-examined.
A paper describing these results by Wright and Drake
appears in the July 28th issue of the journal Nature. NASA's Marshall
Space Flight Center in Huntsville, Alabama, manages the Chandra program
for NASA's Science Mission Directorate in Washington. The Smithsonian
Astrophysical Observatory in Cambridge, Massachusetts, controls
Chandra's science and flight operations.
Fast Facts for GJ 3253:
Credit X-ray: NASA/CXC/Keele Univ/N.Wright et al; Illustration: NASA/CXC/M.Weiss
Scale: X-ray image is 20 arcsec across (about 0.003 light years)
Category: Normal Stars & Star Clusters
Coordinates (J2000): RA 03h 52m 41.70s | Dec +17° 01’ 05.70"
Constellation: Taurus
Observation Date: 25 Sep 2013
Observation Time: 5 hours 45 min.
Obs. ID: 14603
Instrument: ACIS
References: Wright, N. et al, 2016, Nature (accepted)
Color Code: X-ray (Pink)
About: 31 light years (z=0.003)
Source: NASA’s Chandra X-ray Observatory
