#blue stragglers

Messier seems to have a thing for Globular clusters, at least at the start of his catalogue, although to be fair to him, his comments on these objects explains this somewhat.

This Messier described M12 as "A nebula without stars!"

It's easy to forget in a time of Hubble and JWST that Messier was dealing with instruments not that much better than a good pair of binoculars, and to him the object looked like a giant fuzzy patch, with no individual stars showing.

Messier 12 is odd in that it has a surprisingly low amount of the longest lived low mass stars (red dwarfs, K and G type stars), and with an age of 13.8 billion years old (pretty much the age of the universe itself), it's clearly passed through the milky way so many times, many of the lower mass stars have been ejected or found themselves pulled away, and likely now still live on in the central bulge.

M13 - The Great Hercules Cluster

The brightest of the stars in this cluster are the red giants, one in particular V1554 Hercules has an apparent mag 11.95 from 23,000 light years.

Interestingly, there's some blue stars here, but they are not young hot B or O type stars you find in Open Clusters, they are what are known as blue stragglers. Stars are so compressed in the heart of globular clusters that they do regularly merge, and when that happens, a blue straggler can be the product.

M14

Some 30,000 light years away from us in the constellation of Ophiuchus, it's 100 light years across and in total, 400,000 times the mass of our star, 10 times less than the supermassive black hole Sag A*.

M15 - The Great Pegasus Cluster

One of the most densely packed globular clusters known, so much so, the core (central region) has begin to contract in what is known as core collapse, where the mass of stars is so intense, it begins to pull in mass from around it, and most likely forming a intermediate black-hole, although none has ever been confirmed as such.

It is also the only globular cluster to ever be found to have a planetary nebula, Pease 1

This Is How The Universe Makes Blue Stragglers: The Stars That Shouldn't Exist

“New stars form in large clusters, creating stars of all different masses simultaneously. As they age, the more massive stars die first, leaving only the lower-mass ones behind. We can date star clusters by examining which stars remain when we plot out stellar color vs. temperature. The older a cluster is, the redder, lower-mass, and less bright its surviving stars are. Globular star clusters are the oldest; some haven't formed stars in ~13 billion years. Yet if we look closely inside these ancient relics from the young Universe, we'll find a few blue stars.”

Okay, science fans, I’ve got a mystery for you. When you look at a star cluster, you’ll find a wide variety of stars inside: from the ultra-massive, hot, blue ones down to the lower-mass, cool, red ones. The older a cluster is, the redder it is, because the more massive, hotter, bluer ones burn through their fuel faster and die first. But as a cluster gets redder, we’ll inevitably find a few blue stars that don’t belong. These “blue straggler” stars behave as though they’ve formed at a later time than the rest of the cluster, even though we know that cannot be true. Yet they’re real, they’re there, and their lifetimes are often just 10% the known age of the cluster itself.

Each point represents one star. Black points are normal stars. Blue and red points represent blue straggler stars belonging to two clear sequences. The blue solid and blue dashed lines are theoretical model predictions. The left sequence is composed of blue straggler stars formed roughly at the same time. Credit: NAOC     Since the limited amount of gas that survived from the first bulk star-forming process will be quickly expelled within several million years, star clusters have long been thought of as "infertile" stellar systems that cannot form new stars. Only collisions or mergers of stars can lead to rejuvenation of much older stars, making them look younger than most normal stars in much the same way as humans apply facelifts.

Such stars are known as "blue stragglers," because they appear to "straggle" behind the natural evolution of most stars in a star cluster: They still resemble extremely hot (and therefore blue) young stars.

Using the Hubble Space Telescope, an international research team led by Dr. DENG Licai from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) detected an unexpected population of blue straggler stars in a young "globular" cluster, known by its catalogue number NGC 2173.

This is surprising, because blue straggler stars in this cluster seem to have formed in a well-defined burst. The team's findings were published in The Astrophysical Journal.

Messier 53

Messier 53 is a globular star cluster located about 60,000 light years away towards the constellation Coma Berenices. Globular clusters are a type of star cluster containing tens of thousands of stars bound together by gravity. They’re typically found on the edges of galaxies, and over 150 are found in the Milky Way alone.

Globular star clusters are older and larger than open star clusters, and usually contain stars born around the same time. Usually, this means the clusters contain more old, red stars. Messier 53 is unusual for its high number of blue stragglers, a type of rejuvenated star that appears bluer and brighter than its age would suggest. It’s thought that this may be the result of stellar collisions in the dense core of globular clusters.

NGC 6752 - Globular Cluster

The third brightest globular cluster in our skies, and orbiting in the Milky Way's halo, this group of stars are over 10 billion years old (if not more), and yet, look closely and you'll spot a number of bright blue stars, how is this possible for a cluster of such age ? Most blue stars only last a few million years, so what is happening ?

Setting aside the one bright blue star in the image at 11o'clock which is a foreground star, you'll see countless red and blue stars in the cluster, yet there is no star formation going on here.

The vast majority of stars in the cluster are F,G,K,M type stars, stars a little larger than our sun down to red giants, as all the others have long since ended their stellar lives.

However, the blue stars are not new born stars as we often see in nebula, they are what is known as "blue stragglers".

Sometimes all you need is music to rock out to and Blue Stragglers’ groovy and infectious sound certainly delivers.

Electrifying UK rock trio Blue Stragglers will release their second EP ‘Fool’s Errand’ on November 10th, 2023, via Hassle Records. Sometimes all you need is music to rock out to and Blue Stragglers’ groovy and infectious sound certainly delivers. The six-track EP is filled with vigorous energy, affirming melody, and danceable vibes. Kicking off with stupidly anthemic Driverside, a track that is…

Not many bands can claim to have built and then run their own non-profit rehearsal studio but then Blue Stragglers are not like many bands. Having grown up in the town of Horsham – nestled between London and Brighton – Lee Martin (vocals, guitar), Ali Waite (bass) and Andy Head (drums) bonded via a love of bands such as The Raconteurs, PJ Harvey, Supergrass, Demob Happy, Beck, Grandaddy and Jane's Addiction. Skilled players themselves, the trio originally formed the backbone of the much-loved Sussex act Tied to the Mast. But when they struck out on their own to form Blue Stragglers, they were lacking somewhere to hone their craft. And so began the tough but ultimately fruitful challenge of converting an empty space next to a South Downs chalk pit into somewhere they – and other Sussex bands – could practice 24/7.

This DIY dedication to their art is evidenced by the intuition that each member has for the others’ playing, as seen and heard in the supremely powerful live showcases that have secured Blue Stragglers a cult following across England’s southeast, from Brighton via Tunbridge Wells to Horsham and Hastings, alongside some intimate London gigs that first drew the attention of Lost In The Manor records.

Exuding that impenetrable, gang-like identity that’s the preserve of only the best trios, Blue Stragglers been picked up by BBC radio, stolen the show at a number of grassroots festivals and now, thanks to their debut EP release on Lost In The Manor, will be spreading that buzz much, much further afield. A programme of showcase gigs will be announced after the lockdown but in the meantime, you won’t find a better means of banishing the lockdown blues than a healthy blast of Blue Stragglers.