---
title: "Pea galaxy"
chunk: 3/11
source: "https://en.wikipedia.org/wiki/Pea_galaxy"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:15:28.328105+00:00"
instance: "kb-cron"
---

=== 2010 - 2012 ===
In June 2010, authors R. Amorin et al. published a paper in ApJ Letters titled "On the oxygen and nitrogen chemical abundances and the evolution of the "green pea" galaxies". In it they explore issues concerning the metallicity of 79 GPs, disputing the original findings in Cardamone et al. They conclude, "arguing that recent interaction-induced inflow of gas, possibly coupled with a selective metal-rich gas loss drive by supernova winds may explain our findings and the known galaxy properties". For more details see: Two papers by Amorin
In February 2011, authors Y. Izotov et al. published a paper in the ApJ titled "Green Pea Galaxies and Cohorts: Luminous Compact Emission-line Galaxies in the Sloan Digital Sky Survey". They find that the 80 GPs are not a rare class of galaxies on their own, but rather a subset of a class known as 'Luminous Compact Galaxies' (LCGs), of which there are 803. For more details see: Luminous Compact Galaxies
In November 2011, authors Y. Izotov et al. published a paper in A&A titled 'Star-forming galaxies with hot dust emission in the SDSS discovered by the Wide-field Infrared Survey Explorer (WISE)'. In this paper, they find four galaxies that have very red colours in the wavelength range 3.4 micrometres (W1) and 4.6 micrometres (W2). This implies that the dust in these galaxies is at temperatures up to 1000K. These four galaxies are GPs and more than double the number of known galaxies with these characteristics.
In January 2012, authors R. Amorin et al. published a 'Conference proceeding' titled "Unveiling the Nature of the "Green Pea" galaxies". In this publication, they announce that they have conducted a set of observations using the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) at the Gran Telescopio Canarias, and that there is a forthcoming paper about their research. These observations "will provide new insights on the evolutionary state of the Green Peas. In particular, we will be able to see whether the Green Peas show an extended, old stellar population underlying the young starbursts, like those typically dominant in terms of stellar mass in most Blue Compact Galaxies". For more details see: Two papers by Amorin
In January 2012, authors L. Pilyugin et al. published a paper in the MNRAS titled: "Abundance determination from global emission-line SDSS spectra: exploring objects with high N/O ratios". In it they compare the oxygen and nitrogen abundances derived from global emission-line SDSS spectra of galaxies using (i) the electron temperature method and (ii) two recent strong line O/N and N/S calibrations. Three sets of objects were compared: i) Composite hydrogen-rich nebula, ii) 281 SDSS galaxies and iii) A sample of GPs with detectable [OIII]-4363 auroral lines. Among the questions surrounding the GPs is how much nebulae influence their spectra and results. Through comparisons of the three objects using proven methodology and analysis of metallicity, they conclude that "the high nitrogen-to-oxygen ratios derived in some Green Pea galaxies may be caused by the fact that their SDSS spectra are spectra of composite nebulae made up of several components with different physical properties (such as metallicity). However, for the hottest Green Pea galaxies, which appear to be dwarf galaxies, this explanation does not seem to be plausible."
In January 2012, author S. Hawley published a paper in the PASP titled "Abundances in "Green Pea" Star-forming Galaxies". In this paper, former NASA astronaut Steven Hawley compares the results from previous GP papers regarding their metallicities. Hawley compares different ways of calibrating and interpreting the various results, mainly from Cardamone et al. and Amorin et al. but some from Izotov et al., and suggests why the various discrepancies between these papers' findings might be. He also considers such details as the contribution of Wolf–Rayet stars to the gas ionization, and which sets of emission lines give the most accurate results for these galaxies. He ends by writing: "The calibrations derived from the Green Peas differ from those commonly utilized and would be useful if star-forming galaxies like the Green Peas with extremely hot ionizing sources are found to be more common."
In February 2012, authors S. Chakraborti et al. published a paper in The ApJ Letters titled 'Radio Detection of Green Peas: Implications for Magnetic Fields in Young Galaxies'. In this paper, magnetism studies using new data from the Giant Metrewave Radio Telescope describe various observations based around the GPs. They show that the three "very young" starburst galaxies that were studied have magnetic fields larger than the Milky Way. This is at odds with the current understanding that galaxies build up their magnetic properties over time. For more details see: Radio detection
In April 2012, authors R. Amorin et al. published a paper in the ApJ titled "The Star Formation History and Metal Content of the 'Green Peas'. New Detailed GTC-OSIRIS spectrophotometry of Three Galaxies". They give the results for the deep broad-band imaging and long-slit spectroscopy for 3 GPs that had been observed using the OSIRIS instrument, mounted on the 10.4m Gran Telescopio Canarias at the Roque de los Muchachos Observatory. For more details see: GTC-OSIRIS
In August 2012, authors R. Amorín et al. published a paper in the ApJ Letters titled "Complex gas kinematics in compact, rapidly assembling star-forming galaxies". Using the ISIS spectrograph on the William Herschel Telescope, they publish results of the high-quality spectra that they took of six galaxies, five of which are GPs. After studying the hydrogen alpha emission lines (ELs) in the spectra of all six, it is shown that these ELs are made up of multiple lines, meaning that the GPs have several chunks of gas and stars moving at large velocities relative to each other. These ELs also show that the GPs are effectively a 'turbulent mess', with parts (or clumps) moving at speeds of over 500 km/s (five hundred km/s) relative to each other.