A recent acquisition from the NASA/ESA Hubble Space Telescope presents an exceptional depiction of Arp 4, a celestial pairing of galaxies situated within the constellation Cetus.
This Hubble image shows the galaxy pair Arp 4. Image credit: NASA / ESA / Hubble / J. Dalcanton, Dark Energy Survey / DOE / FNAL / DECam / CTIO / NOIRLab / NSF / AURA.
The celestial entity known as Arp 4 is comprised of two galaxies: the diminutive, luminous spiral galaxy designated MCG-02-05-050a and the considerably more vast spiral galaxy, MCG-02-05-050.
This galactic duo, found within the celestial confines of Cetus, was initially observed and documented by the Dutch-Canadian astronomer Sidney van den Bergh in the year 1959.
Arp 4 holds the fourth position in Halton Arp’s esteemed Atlas of Peculiar Galaxies, and it represents one of six celestial objects within the ‘low surface brightness galaxies’ classification.
“The designation Arp 4 originates from the Atlas of Peculiar Galaxies, a compilation initiated in the 1960s by the astronomer Halton Arp,” the Hubble astronomers detailed in an official statement.
“This collection featured ‘unusual galaxies’ that were meticulously chosen and photographed to exemplify atypical and irregular morphologies, thereby facilitating the investigation of galactic evolutionary pathways leading to such forms.”
Throughout its operational tenure, the Hubble telescope has profoundly transformed our comprehension of galaxies, revealing an array of remarkably peculiar specimens from Arp’s catalog.
Within this compendium, the initial galaxies, such as Arp 4, are categorized as low surface brightness galaxies—a classification denoting galaxies that exhibit an unexpected faintness and present considerable detection challenges.
“The substantial galaxy featured herein, also cataloged as MCG-02-05-050, aligns perfectly with this description, characterized by its fragmented spiral arms and a subdued galactic disk,” the astronomers remarked.
“Its smaller companion, MCG-02-05-050a, presents as a far brighter and more dynamically active spiral galaxy.”
“A key point of clarification is that these galaxies are not in close physical proximity,” they clarified.
“The expansive blue galaxy, MCG-02-05-050, is situated at a cosmic distance of 65 million light-years from Earth.”
“Its luminous, smaller counterpart, MCG-02-05-050a, resides at a staggering distance of 675 million light-years, placing it over tenfold further away!”
“Consequently, it is probable that MCG-02-05-050a is indeed the more massive galaxy of the pair, with MCG-02-05-050 being comparatively smaller.”
“Their alignment within this observational image is merely an improbable visual happenstance,” they observed.
“Despite the absence of a physical connection between them, our vantage point from Earth affords us the privilege of appreciating Arp 4 as an extraordinary celestial pairing gracing the night sky.”
