A cosmological measuring tape

Esahubble_potw1513a_1024

esahubble_potw1513a March 30th, 2015

Credit: NASA & ESA Acknowledgement: A. Riess (STScI)

This NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 3021 which lies about 100 million light-years away in the constellation of Leo Minor (The Little Lion). Among many other types of stars, this galaxy contains Cepheid variable stars, which can be used work out the distance to the galaxy. These stars pulsate at a rate that is closely related to their intrinsic brightness, so measurements of their rate of pulsation and their observed brightness give astronomers enough information to calculate the distance to the galaxy itself. Cepheids are also used to calibrate an even brighter distance marker, that can be used over greater distances: Type Ia supernovae. One of these bright exploding stars was observed in NGC 3021, back in 1995. In addition, the supernova in NGC 3021 was also used to refine the measurement of what is known as the Hubble constant. The value of this constant defines how fast the Universe is expanding and the more accurately we know it the more we can understand about the evolution of the Universe in the past as well as in the future. So, there is much more to this galaxy than just a pretty spiral.

Provider: Hubble Space Telescope | ESA

Image Source: https://www.spacetelescope.org/images/potw1513a/

Curator: ESA/Hubble, Garching bei München, Germany

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
NGC 3021
Subject - General
Galaxy > Type > Spiral
Esahubble_potw1513a_128
 

Position Details

Position (ICRS)
RA = 9h 50m 59.1s
DEC = 33° 33’ 5.3”
Orientation
North is 6.9° CW
Field of View
2.9 x 2.7 arcminutes
Constellation
Leo Minor

Color Mapping

  Telescope Spectral Band Wavelength
Red Hubble (ACS) Infrared (I) 814.0 nm
Blue Hubble (ACS) Optical (V) 555.0 nm
Spectrum_base
Red
Blue
Esahubble_potw1513a_1280
×
ID
potw1513a
Subject Category
E.5.1.1  
Subject Name
NGC 3021
Credits
NASA & ESA Acknowledgement: A. Riess (STScI)
Release Date
2015-03-30T10:00:00
Lightyears
Redshift
Reference Url
https://www.spacetelescope.org/images/potw1513a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope
Instrument
ACS, ACS
Color Assignment
Red, Blue
Band
Infrared, Optical
Bandpass
I, V
Central Wavelength
814, 555
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
147.746095754, 33.5514856259
Reference Dimension
3527.0, 3191.0
Reference Pixel
1763.0, 1595.0
Scale
-1.38576877347e-05, 1.38576877347e-05
Rotation
-6.86
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
ESA/Hubble
URL
http://www.spacetelescope.org/
Name
Email
Telephone
Address
Karl-Schwarzschild-Strasse 2
City
Garching bei München
State/Province
Postal Code
D-85748
Country
Germany
Rights
Creative Commons Attribution 4.0 International License
Publisher
ESA/Hubble
Publisher ID
esahubble
Resource ID
potw1513a
Metadata Date
2014-11-28T19:14:29+01:00
Metadata Version
1.1
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Detailed color mapping information coming soon...

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There is no distance meta data in this image.

 

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