Donatiello I

Lore & Background

Donatiello I was discovered by Italian amateur astronomer and astrophotographer Giuseppe Donatiello in 2016 while reviewing his archival long exposures from 2010 and 2013, taken with a custom-built 12.7 centimetre telescope in Pollino National Park. The galaxy was first sighted in a 6000-second exposure of the area around the Andromeda Galaxy. Follow-up observations with the Roque de los Muchachos Observatory's Galileo National Telescope and Gran Telescopio Canarias on 27 November 2016 led to a scientific paper published in December 2018.

The galaxy is a dwarf spheroidal with an estimated distance between 8.1 and 11.4 million light-years from Earth, outside the Local Group. It is populated with metal-poor red dwarfs and shows no active star formation. Its nearest neighbor is NGC 404, located about 211,000 light-years away, and Donatiello I may have been involved in or affected by a possible merger between NGC 404 and an irregular dwarf galaxy around 900 million years ago.

Reader's Guide

Donatiello I holds significance as one of the most isolated dwarf spheroidal galaxies known, yet it is a possible satellite of NGC 404, 'Mirach's Ghost'. Its discovery by an amateur astronomer using archival images highlights the role of citizen scientists in modern astronomy. The galaxy's nickname, 'Mirach's Goblin', reflects its proximity to the star Mirach and its possible physical association with NGC 404. The discovery was corroborated by the Sloan Digital Sky Survey and professional follow-up observations, leading to a peer-reviewed paper. The authors suggested further detailed observations with the Hubble Space Telescope to better determine the galaxy's distance, its relationship with NGC 404, and its size and mass. Donatiello I thus represents a bridge between amateur and professional astronomy, and its study may shed light on the dynamics of dwarf galaxies in the local universe.

Did You Know?

• Donatiello I is nicknamed 'Mirach's Goblin' due to its proximity to the star Mirach and the galaxy NGC 404, 'Mirach's Ghost'.
• It was discovered by Italian amateur astronomer Giuseppe Donatiello in 2016 while reviewing archival exposures from 2010 and 2013.
• Its distance from Earth is estimated between 8.1 and 11.4 million light-years.