“Late-type” galaxy?

Esahubble_potw2347a_1024

esahubble_potw2347a November 20th, 2023

Credit: ESA/Hubble & NASA, C. Kilpatrick

This Hubble Picture of the Week features NGC 2814, an irregular galaxy that lies about 85 million light years from Earth. In this image, which was captured using Hubble’s Advanced Camera for Surveys (ACS), the galaxy appears to be quite isolated: visually, it looks a little like a loose stroke of bright paint across a dark background. However, looks can be deceiving. NGC 2814 actually has three close (in astronomical terms) galactic neighbours: a side-on spiral galaxy known as NGC 2820; an irregular galaxy named IC 2458; and a face-on non-barred spiral galaxy called NGC 2805. Collectively, the four galaxies make up a galaxy group known as Holmberg 124. In some literature these galaxies are referred to as a group of ‘late-type galaxies’. The terminology ‘late-type’ refers to spiral and irregular galaxies, whilst ‘early-type’ refers to elliptical galaxies. This rather confusing terminology has led to a common misconception within the astronomy community. It is still quite widely believed that Edwin Hubble inaccurately thought that elliptical galaxies were the evolutionary precursors to spiral and irregular galaxies, and that that is the reason why ellipticals are classed as ‘early-type’ and spirals and irregulars are classed as ‘late-type’. This misconception is due to the Hubble ‘tuning fork’ of galactic classification, which visually shows galaxy types proceeding from elliptical to spiral, in a sequence that could easily be interpreted as a temporal evolution. However, Hubble actually adopted the terms ‘early-type’ and ‘late-type’ from much older astronomical terminology for stellar classifications, and did not mean to state that ellipticals were literally evolutionary precursors to spiral and irregular galaxies. In fact, he explicitly said in his 1927 paper that ‘the nomenclature … [early and late] … refers to position in the sequence, and temporal connotations are made at one’s peril’. Despite Hubble himself being quite emphatic on this topic, the misunderstanding persists almost a hundred years later, and perhaps provides an instructive example of why it is helpful to classify things with easy-to-interpret terminology from the get-go! [Image Description: An irregular galaxy, a narrow streak of stars crossed by faint dust lanes. It is surrounded by a bright glow, appearing like a beam of light in the centre of a dark background. A scatter of small, distant galaxies and a single, bright star surround the galaxy.] Links Pan: “Late-type” galaxy?

Provider: Hubble Space Telescope | ESA

Image Source: https://esahubble.org/images/potw2347a/

Curator: ESA/Hubble, Baltimore, MD, United States

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
NGC 2814
Esahubble_potw2347a_128
 

Position Details

Position (ICRS)
RA = 9h 21m 11.0s
DEC = 64° 15’ 6.4”
Orientation
North is 104.8° CCW
Field of View
3.0 x 2.0 arcminutes
Constellation
Ursa Major

Color Mapping

  Telescope Spectral Band Wavelength
Blue Hubble (ACS) Optical (V) 555.0 nm
Green Hubble (ACS) Optical (V) 555.0 nm
Green Hubble (ACS) Optical (I) 814.0 nm
Red Hubble (ACS) Optical (I) 814.0 nm
Spectrum_base
Blue
Green
Green
Red
Esahubble_potw2347a_1280
×
ID
potw2347a
Subject Category
Subject Name
NGC 2814
Credits
ESA/Hubble & NASA, C. Kilpatrick
Release Date
2023-11-20T06:00:00
Lightyears
Redshift
Reference Url
https://esahubble.org/images/potw2347a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope
Instrument
ACS, ACS, ACS, ACS
Color Assignment
Blue, Green, Green, Red
Band
Optical, Optical, Optical, Optical
Bandpass
V, V, I, I
Central Wavelength
555, 555, 814, 814
Start Time
Integration Time
Dataset ID
None, None, None, None
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
140.29595676633252, 64.25177887610506
Reference Dimension
3589.0, 2393.0
Reference Pixel
1794.5, 1196.5
Scale
-1.3884271783718225e-05, 1.3884271783718225e-05
Rotation
104.82000000000001
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
ESA/Hubble
URL
https://esahubble.org
Name
Email
Telephone
Address
ESA Office, Space Telescope Science Institute, 3700 San Martin Dr
City
Baltimore
State/Province
MD
Postal Code
21218
Country
United States
Rights
Creative Commons Attribution 4.0 International License
Publisher
ESA/Hubble
Publisher ID
esahubble
Resource ID
potw2347a
Metadata Date
2023-11-15T00:17:03+01:00
Metadata Version
1.1
×

 

Detailed color mapping information coming soon...

×

There is no distance meta data in this image.

 

Providers | Sign In