NGC 7789 Caroline's Rose.

 

NGC 7789 Caroline's Rose Open Cluster in the Constellation Cassiopeia.
PIRATE Robotic Telescope BVR and Clear filters, Tenerife.
Data Credit: telescope.org, Open Observatories, Open University.
Image credit: Kurt Thrust 

" Caroline Herschel, the sister of the 18th century astronomer William, was an accomplished astronomer and observer in her own right. Amongst other things, she discovered eight comets and catalogued over 500 previously undiscovered stars. She was the first woman to be awarded the Gold Medal of the UK's Royal Astronomical Society in 1838.   A woman being recognised and accepted as 

a scientist in the 18th and 19th  centuries was quite unique and extraordinary"! - Joel Cairo CEO of the Jodrell Plank Observatory.

Caroline Herschel:
image courtesy of the Sheila Terry/Science Photo Library and BBC News. 

"NGC 7789, often called Caroline’s Rose, represents one of the Milky Way’s most elegant open clusters, a stellar congregation whose appearance evokes the layered whorls of a rose when viewed through a telescope. Situated in the constellation Cassiopeia, the cluster lies roughly 7,600 light-years from Earth and contains several thousand stars spread across nearly a half-degree of sky. Though not as youthful as some open clusters, it remains dynamically rich: its stars span a range of evolutionary stages, from bright main-sequence members to numerous red giants that testify to the cluster’s intermediate age of around 1.6 billion years. This mixture produces an array of contrasting luminosities, giving the cluster its characteristic mottled structure and the visual illusion of floral petals.

The object’s historical significance is deeply linked to Caroline Herschel, the pioneering 18th-century astronomer who discovered it in 1783. Working from the Herschel family observatory in England, she methodically surveyed the northern sky with telescopes constructed by her brother, William Herschel, contributing some of the first systematic catalogs of star clusters and nebulae. Although her work was often overshadowed by her brother’s reputation, she distinguished herself as a precise and dedicated observer, ultimately becoming one of the first women recognized formally for contributions to astronomy.

Her discovery of NGC 7789 exemplifies the methodical and careful sky-mapping that characterized her work. Long before astrophysical interpretations of cluster ages, metallicity, or stellar evolution existed, she recognized the object as a coherent and noteworthy celestial assembly. Today, Caroline’s Rose remains both a physical laboratory for the study of stellar evolution and a historical monument to her scientific skill, perseverance, and enduring legacy in the advancement of observational astronomy" - Karl Segin outreach officer at the JPO (the UK's most easterly Observatory).

The widefield view of NGC 7789
taken with the Seestar S30 from the JPO
Image Credit: Kurt Thrust.

Messier 37- Open star cluster in the Constellation Auriga

Messier 37 - Combined image - stack of 10 x 30sec lights with the Altair 66mm Doublet wide-field scope  from the Jodrell Plank Observatory (Credit: Archie Mendes) and  1x 180sec light with the PIRATE robotic telescope (Credit: telescope.org - Open University) - combined using Registar Software -(Credit: Pip Stakkert)

"Open star clusters are collections of up to a few thousand stars loosely bound by mutual gravitational attraction. The stars in an open cluster form from the same giant molecular cloud of gas and dust. More than 1100 open clusters have been found in the Milky Way. Open clusters are  found  only in spiral and irregular galaxies where active star formation is occurring. They generally survive for a few hundred million years before the stars disperse as the result of galactic migration and disturbance in close encounters with other clusters. Massive clusters may stay together longer surviving for a few billion years.
Messier 37 is the richest open star cluster in the constellation Auriga and is approximately 4500 light years distant. So the light we collected the other night from M37 set off from the cluster when on Earth the Pyramids were being constructed. The cluster has an estimated combined mass of 1500 suns and angular diameter of 24 arc minutes which corresponds to a dimension of 20 to 25 light years. Messier 37 is somewhere between 350 and 550 million years old - in cosmic terms quite young - younger than the Hyades but older than the Pleiades". - Kurt Thrust - acting CEO and current Director of the Jodrell Plank Observatory.