The Shocking Behavior of a Speedy Star

Spitzer_sig14-003_1024

spitzer_sig14-003 February 20th, 2014

Credit: NASA/JPL-Caltech

Roguish runaway stars can have a big impact on their surroundings as they plunge through the Milky Way galaxy. Their high-speed encounters shock the galaxy, creating arcs, as seen in this newly released image from NASAs Spitzer Space Telescope.

In this case, the speedster star is known as Kappa Cassiopeiae, or HD 2905 to astronomers. It is a massive, hot supergiant. But what really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy.

Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzers infrared detectors.

Incredibly, this shock is created about 4 light-years ahead of Kappa Cassiopeiae, showing what a sizable impact this star has on its surroundings. (This is about the same distance that we are from Proxima Centauri, the nearest star beyond the sun.)

The Kappa Cassiopeiae bow shock shows up as a vividly red color. The faint green features in this image result from carbon molecules, called polycyclic aromatic hydrocarbons, in dust clouds along the line of sight that are illuminated by starlight.

Delicate red filaments run through this infrared nebula, crossing the bow shock. Some astronomers have suggested these filaments may be tracing out features of the magnetic field that runs throughout our galaxy. Since magnetic fields are completely invisible themselves, we rely on chance encounters like this to reveal a little of their structure as they interact with the surrounding dust and gas.

Kappa Cassiopeiae is visible to the naked eye in the Cassiopeia constellation (but its bow shock only shows up in infrared light.)

For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red.

Provider: Spitzer Space Telescope

Image Source: http://www.spitzer.caltech.edu/images/5730-sig14-003-The-Shocking-Behavior-of-a-Speedy-Star

Curator: Spitzer Space Telescope, Pasadena, CA, USA

Image Use Policy: http://www.spitzer.caltech.edu/info/18-Image-Use-Policy

Image Details

Image Type
Observation
Object Name
Kappa Cassiopeiae Kappa Cas HD2905
Subject - Milky Way
Star > Evolutionary Stage > Blue Supergiant
Star > Circumstellar Material > Outflow

Distance

Universescale1
4,000 light years
Spitzer_sig14-003_128
 

Position Details

Position (ICRS)
RA = 0h 33m 8.4s
DEC = 62° 55’ 57.7”
Orientation
North is 151.7° CCW
Field of View
24.7 x 18.8 arcminutes
Constellation
Cassiopeia

Color Mapping

  Telescope Spectral Band Wavelength
Blue Spitzer (IRAC) Infrared (Near-IR) 3.6 µm
Cyan Spitzer (IRAC) Infrared (Near-IR) 4.5 µm
Green Spitzer (IRAC) Infrared (Mid-IR) 8.0 µm
Red Spitzer (MIPS) Infrared (Mid-IR) 24.0 µm
Spectrum_ir1
Blue
Cyan
Green
Red
Spitzer_sig14-003_1280
×
ID
sig14-003
Subject Category
B.3.1.6   B.3.7.3  
Subject Name
Kappa Cassiopeiae, Kappa Cas, HD2905
Credits
NASA/JPL-Caltech
Release Date
2014-02-20
Lightyears
4,000
Redshift
4,000
Reference Url
http://www.spitzer.caltech.edu/images/5730-sig14-003-The-Shocking-Behavior-of-a-Speedy-Star
Type
Observation
Image Quality
Good
Distance Notes
Facility
Spitzer, Spitzer, Spitzer, Spitzer
Instrument
IRAC, IRAC, IRAC, MIPS
Color Assignment
Blue, Cyan, Green, Red
Band
Infrared, Infrared, Infrared, Infrared
Bandpass
Near-IR, Near-IR, Mid-IR, Mid-IR
Central Wavelength
3600, 4500, 8000, 24000
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
8.2848535, 62.9326954
Reference Dimension
2470.0, 1880.0
Reference Pixel
1236.0, 941.0
Scale
0.000166756, 0.00016675574
Rotation
151.72
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
Spitzer Space Telescope
URL
http://www.spitzer.caltech.edu
Name
Email
Telephone
Address
1200 E. California Blvd.
City
Pasadena
State/Province
CA
Postal Code
91125
Country
USA
Rights
http://www.spitzer.caltech.edu/info/18-Image-Use-Policy
Publisher
Spitzer Science Center
Publisher ID
spitzer
Resource ID
sig14-003.tif
Metadata Date
2014-03-06
Metadata Version
1.1
×

 

Detailed color mapping information coming soon...

×
Universescalefull
4,000 light years

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