SN 1885A: The Only Supernova Ever Seen in the Andromeda Galaxy
For astronomers, observing events in other galaxies is a cornerstone of our understanding of the universe. Among these cosmic spectacles, supernovae – the explosive deaths of stars – hold a special place. Today, we shine a spotlight on a particularly significant event: SN 1885A, also known as S Andromedae.
A Historic Discovery
SN 1885A is remarkable for one primary reason: it is the only supernova that has ever been observed in the Andromeda Galaxy (M31). Its discovery in August 1885 marked a pivotal moment, as it was the first supernova witnessed outside our own Milky Way galaxy. While not fully appreciated at the time due to its immense distance, this event provided invaluable data for future studies.
The Unraveling of its Discovery
The initial sighting of SN 1885A is attributed to French astronomer Ludovic Gully on August 17, 1885, during a public stargazing event. However, he mistook the bright object for scattered moonlight in his telescope and did not pursue the observation further. Independently, Irish amateur astronomer Isaac Ward in Belfast claimed to have seen the phenomenon on August 19, 1885, but his findings were not immediately published.
The definitive confirmation and widespread observation of SN 1885A were initiated by German astronomer Ernst Hartwig at the Tartu Observatory in Estonia. Hartwig independently detected the supernova on August 20, 1885. He communicated his findings via telegram on August 31, 1885, after verifying that the object was not a result of reflected moonlight.
Hartwig's telegram spurred immediate and widespread observations, prompting others, including Ward and Gully, to publish their earlier sightings. However, historical analyses by Kenneth Glyn Jones and others cast doubt on the accuracy of Ward's observations due to discrepancies in his estimated magnitude compared to the reconstructed light curve. Consequently, Ernst Hartwig is widely credited as the discoverer of this significant extragalactic supernova.
The Enigmatic Dark Spot
When observing the remnant of SN 1885A, astronomers have noted a peculiar dark spot. This feature is not an artifact but a real phenomenon, observable when the correct filters are used during observation, as detailed in scientific papers exploring the supernova remnant.
SN 1885A remains a unique and important celestial event, offering a tangible link to the dramatic processes occurring in distant galaxies and a testament to the persistent efforts of astronomers throughout history.
