Haro 11 (H11) is a small galaxy at a distance of (

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

z=0.020598). It is situated in the southern constellation of

Sculptor Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

. Visually, it appears to be an irregular galaxy, as the ESO image to the right shows. H11 is named after

Guillermo Haro Guillermo Haro Barraza (; 21 March 1913 – 26 April 1988) was a Mexican astronomer. Through his own astronomical research and the formation of new institutions, Haro was influential in the development of modern observational astronomy in M ...

, a Mexican astronomer who first included it in a study published in 1956 about blue galaxies. H11 is a starburst galaxy that has 'super star clusters' within it and is one of nine galaxies in the local universe known to emit Lyman continuum photons (LyC).

Background

first described H11 in a study published in 1956 listing 44 galaxies that were blue. The observations had been carried out at the Tonantzintla Observatory in Mexico using the Schmidt Camera. Since then, The NASA/IPAC Extragalactic Database (NED) gives 123 citations for H11. The first study showing the possible escape of Lyman continuum photons was published in 2006, using data from the

Far Ultraviolet Spectroscopic Explorer Far Ultraviolet Spectroscopic Explorer (FUSE, Explorer 77, and MIDEX-0) represented the next generation, high-orbit, ultraviolet space observatory covering the wavelength range of 90.5–119.5 nanometre (nm) of the NASA operated by the Johns Ho ...

(FUSE). The study's aim was to select "an extreme starburst dwarf, the Blue Compact Galaxy Haro 11, with the aim of determining the Lyman continuum escape fraction from UV spectroscopy." The image in the information box above right was made combining data from ESO's

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, ...

and the NASA/ESA Hubble Space Telescope. A team of astronomers at Stockholm University, Sweden, and the Geneva Observatory, Switzerland, identified 200 separate clusters of very young, massive stars, many of which are less than 10 million years old. The observations have led the astronomers to conclude that H11 is most likely the result of a merger between a galaxy that is rich in stars and a younger, gas-rich galaxy.

Lyman Continuum Photons

Haro 11 is one of nine galaxies in the local universe that have been identified as leaking Lyman Continuum photons. LyC leakage is crucial to the process known as

Reionization In the fields of Big Bang theory and cosmology, reionization is the process that caused matter in the universe to reionize after the lapse of the " dark ages". Reionization is the second of two major phase transitions of gas in the universe (t ...

which is theorised to have occurred between redshift z=11 and z=7, that is to say within the first 10% of the age of the Universe. Reionization, or The Epoch of Reionization (EofR), is the period during which the gas in the early Universe went from being almost completely neutral to a state in which it became almost completely ionized. The EofR is intimately linked to many fundamental questions in cosmology, structure formation and evolution.

The Kinematics of Haro 11

In November 2015, a study was published in the journal

Astronomy and Astrophysics ''Astronomy & Astrophysics'' is a monthly peer-reviewed scientific journal covering theoretical, observational, and instrumental astronomy and astrophysics. The journal is run by a Board of Directors representing 27 sponsoring countries plus a re ...

by Göran Östlin et al. which examined the kinematics of H11 using observations collected at the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...

, Paranal, Chile. The study also compared H11 to The

Antennae Galaxies The Antennae Galaxies (also known as NGC 4038/NGC 4039 or Caldwell 60/Caldwell 61) are a pair of interacting galaxy, interacting galaxies in the constellation Corvus (constellation), Corvus. They are currently going through a Starburst Galaxies, ...

(NGC 4038), a pair of interacting galaxies. The abstract states: "In this work, we investigate the kinematics of stars and ionised gas in Haro 11, one of the most luminous blue compact galaxies in the local Universe." Further on, the abstract states: "Hence the complexities reveal real dynamical disturbances providing further evidence for a merger in Haro 11." The abstract finishes with: "Haro 11 shows many resemblances with the famous Antennae galaxies both morphologically and kinematically, but it is much denser, which is the likely explanation for the higher star formation efficiency in Haro 11."

Further Studies

In September 2003, as a result of Program 9470, Daniel Kunth and team published the first images of Haro 11 using the then newly installed ACS on the HST (specifically the Solar Blind Channel) in a study titled: "The First Deep Advanced Camera for Surveys Lyalpha Images of Local Starburst Galaxies". The abstract for Kunth et al. states: "The ACS imaging reveals a complex Lyalpha morphology, with sometimes strong offsets between the emission of Lyalpha and the location of stellar light, ionized gas traced by Halpha, and the neutral gas. Overall, more Lyalpha photons escape from the more metal- and dust-rich galaxy ESO 350-IG038 aro 11"

References

External links