Hubble Heritage Archive: Protostar IRAS 20324+4057

The text and images in this article were originally published on August 29, 2013, and reflect information about IRAS 20324+4057 available at that time.

NASA’s Hubble Sees a Cosmic Caterpillar

This light-year-long knot of interstellar gas and dust resembles a caterpillar on its way to a feast. But the meat of the story is not only what this cosmic caterpillar eats for lunch, but also what’s eating it. Harsh winds from extremely bright stars are blasting ultraviolet radiation at this “wanna-be” star and sculpting the gas and dust into its long shape. 

The culprits are 65 of the hottest, brightest known stars, classified as O-type stars, located 15 light-years away from the knot, towards the right edge of the image. These stars, along with 500 less bright, but still highly luminous B-type stars make up what is called the Cygnus OB2 association. Collectively, the association is thought to have a mass more than 30,000 times that of our Sun. 

The caterpillar-shaped knot, called IRAS 20324+4057, is a protostar in a very early evolutionary stage. It is still in the process of collecting material from an envelope of gas surrounding it. However, that envelope is being eroded by the radiation from Cygnus OB2. Protostars in this region should eventually become young stars with final masses about one to ten times that of our Sun, but if the eroding radiation from the nearby bright stars destroys the gas envelope before the protostars finish collecting mass, their final masses may be reduced. 

Spectroscopic observations of the central star within IRAS 20324+4057 show that it is still collecting material quite heavily from its outer envelope, hoping to bulk up in mass. Only time will tell if the formed star will be a “heavy-weight” or a “light-weight” with respect to its mass. 

This image of IRAS 20324+4057 is a composite of Hubble Advanced Camera for Surveys data taken in green and infrared light in 2006, and ground-based hydrogen data from the Isaac Newton Telescope in 2003, as part of the INT Photometric H-alpha Survey (IPHAS). The object lies 4,500 light-years away in the constellation Cygnus. 

Featured Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and IPHAS

Fast Facts about IRAS 20324+4057

About this Object

Object Name:IRAS 20324+4057
Object Description:Protostar in the Cygnus OB2 Association
Position (J2000.0):
RA: 20h 34m 14s.12 
Dec: +41° 08′ 03″.55 
Distance:4,500 light-years (1,380 megaparsecs) 

About the Data

Data Description: The image was created from Hubble data from proposal 10536: R. Sahai (Jet Propulsion Laboratory), M. Morris (UCLA), C.S. Contreras (CSIC/INTA), M. Claussen (Associated Universities, Inc.), and S. Salim (Indiana University). The science teams include: N. Wright, J. Drake, M. Guarcello, and L. Hora (Harvard-Smithsonian Center for Astrophysics), J. Drew (University of Hertfordshire), R. Gutermuth (University of Massachusetts, Amherst), and K. Kraemer (Harvard-Smithsonian Center for Astrophysics/Boston College); and R. Sahai (Jet Propulsion Laboratory), M. Morris (UCLA), and M. Claussen (Associated Universities, Inc.).
Instrument: ACS/WFC
Filters: F606W (V) and F814W (I)
Exposure Date: July 22, 2006

About this Image

Note: Hubble data of IRAS 20324+4057 have been combined with ground-based H-alpha observations taken in 2003 with the Isaac Newton Telescope (INT) to create the composite image. 
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and the IPHAS Survey
Release Date: August 29, 2013
Color: This image is a composite of separate exposures acquired by the ACS instrument and the Isaac Newton Telescope. Several filters were used to sample various wavelengths. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:

INT: Hα cyan
ACS: F606W (V) blue
ACS: F814W (I) red

Additional Information on IRAS 20324+4057

The Bigger Picture: 
A Region in the Cygnus Molecular Cloud:

The above image is a composite of Digitized Sky Survey blue and red data and data from the Issac Newton Telescope Photometric H-alpha Survey. The entire image is a portion of the Cygnus Molecular Cloud. The inset is the area contained in the image below. The below image inset is the location of the IRAS 20324+4057 protostar.

Image Credits: 

Visit for a Zoom into IRAS 20324+4057

Additional Images of IRAS 20324+4057


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