Messier 31 revisited

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Messier 31 The Andromeda Galaxy Group. Altair Lightwave 66mm ED refractor and Canon 600d DSLR.
Image Credit Kurt Thrust.

"Our nearest spiral galaxy neighbour the Andromeda Galaxy is riding high in the Northern Hemisphere autumn sky. The weather has been far from kind and the JPO team has been laid low by a rather nasty virus which may be the latest variant of  Covid. Anyway, as the team has been wrapped up warm for a while, Kurt decided to reprocess this data captured in a previous year.

The above image shows the three galaxies M31 (the large central inclined spiral), M32 the elliptical galaxy (appears as a fuzzy spot on the upper edge of the M31 spiral) and M110 a dwarf elliptical galaxy ( just below and to the centre right of M31). 

So let Professor G.P.T. Chat, our visiting astrophysicist, compare and contrast these nearby galaxies (approximately 2.5 million light years distant) with our home Milky Way galaxy". - Joel Caio CEO of the Jodrell Plank Observatory.

Milky Way – Our Home Galaxy

The Milky Way is itself a barred spiral galaxy, somewhat smaller than M31. Its disk extends ~100,000–120,000 light-years, with a mass of about 1 trillion solar masses and a few hundred billion stars. Structurally, it resembles M31: both have stellar halos, bulges, bars, spiral arms, and satellite galaxies. In cosmic terms, the Milky Way is the second major member of the Local Group, and the future collision and merger of the Milky Way and M31 will reshape them into a single giant elliptical galaxy in several billion years.

M31 – The Andromeda Galaxy

Andromeda is the giant of this quartet. With a disk spanning about 220,000 light-years, it is roughly twice the diameter of the Milky Way. Its stellar population approaches one trillion, compared with the Milky Way’s 200–400 billion. In both size and luminosity, M31 slightly outclasses our own Galaxy, and it exerts enough gravitational pull to dominate the Local Group, which also contains the Milky Way and dozens of smaller galaxies.

• Diameter: ~220,000 light-years (about twice the Milky Way’s diameter).
• Mass: ~1.5 trillion solar masses.
• Stars: ~1 trillion.
• Luminosity: ~2.6 × 10¹⁰ solar luminosities.

Notes: A vast spiral galaxy with an extensive stellar halo and a large, bright disk. It dominates the Local Group both in size and gravitational influence.

M32 – Compact Elliptical

Placed against the scale of the Milky Way, M32 looks minuscule. With only ~3 billion stars in a body just 6,500 light-years across, it is smaller than even some of the Milky Way’s largest globular clusters when measured by diameter. Where the Milky Way’s spiral disk is rich in gas and dust and actively forming stars, M32 is stripped bare, almost entirely quiescent. Its compact, blazing core makes it bright for its size, but compared with the Milky Way, it is less than 1% as luminous.

• Diameter: ~6,500 light-years (tiny compared with M31).
• Mass: ~3 × 10⁹ solar masses.
• Stars: ~3 billion.
• Luminosity: ~3 × 10⁸ solar luminosities.

Notes: Dense and bright, especially in its central regions. Its outer stars and gas are thought to have been stripped by M31, leaving only the compact core we see today.

M110 – Dwarf Elliptical

M110 sits somewhere between M32 and the Milky Way in scale. Its 15,000–17,000 light-year span is still tiny compared with the Milky Way’s disk, and its ~10 billion stars are a mere fraction of the Milky Way’s population. Unlike M32, however, M110 retains some irregular features, dust, and evidence of star formation. It is a faint satellite, thousands of times less luminous than the Milky Way, but still large enough to stand as one of the more substantial dwarf galaxies in the Local Group.

• Diameter: ~15,000–17,000 light-years.
• Mass: ~1–2 × 10⁹ solar masses.
• Stars: ~10 billion.
• Luminosity: ~9 × 10⁸ solar luminosities.

Notes: More diffuse than M32, with some evidence of dust lanes and past star formation. Its structure is irregular compared with typical smooth ellipticals, likely reflecting tidal interaction with M31.

Comparative Perspective

M31 and the Milky Way are the two great spirals of the Local Group, differing mainly in scale (M31 being the larger).

M32 is a stripped-down remnant, a tiny elliptical companion of M31, utterly dwarfed by both the Milky Way and Andromeda.

M110 is a diffuse dwarf elliptical, more extended than M32 but still only a faint shadow of the Milky Way’s scale and richness.

Together, these four galaxies illustrate the hierarchy of galactic forms: two massive spirals shaping the Local Group, orbited by much smaller companions that bear the scars of their gravitational relationship with the giants.

The Approaching Collision

• The Milky Way and M31 are moving toward each other at about 110 km/s.

• In roughly 4–5 billion years, their outer halos will begin to overlap, triggering the first close passage.

• The collision will not be like two solid bodies smashing together; instead, stars will mostly pass by one another because of the vast spaces between them. But gas, dust, and dark matter halos will interact strongly, producing shocks, bursts of star formation, and tidal distortions.

The Merger

• After a series of close encounters, the Milky Way and M31 will merge into a single giant elliptical galaxy — sometimes nicknamed “Milkomeda” or “Milkdromeda.”

• This process will take several billion years to settle into a stable form. The final product will likely resemble today’s giant elliptical galaxies, with a vast stellar halo and little organized spiral structure.

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The Fate of M32

• M32, already stripped and compact, is tightly bound to M31.

• During the merger, it will almost certainly be swallowed whole by the combined Milky Way–Andromeda system.

• Its compact nature means it will survive tidal forces fairly well, likely ending as a dense nucleus or central star cluster within the merged galaxy.

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The Fate of M110

• M110, being larger and more diffuse, will fare differently.

• It may be torn apart by tidal forces during the merger, with its stars spread out into long stellar streams and absorbed into the halo of the new galaxy.

• Some fraction of its stars may survive as a remnant dwarf core, but it will be much more disrupted than M32.

The Long-Term Result

• The Local Group will transform from a system dominated by two spirals into a single elliptical super-galaxy, containing perhaps 2 trillion stars.

• The smaller companions, including M32, M110, and the Milky Way’s own satellites (like the Magellanic Clouds), will either be absorbed into the giant remnant or left orbiting as faint shells and streams.

• From a cosmic distance, the Local Group will eventually resemble a single luminous elliptical galaxy, drifting in relative isolation as the universe continues to expand.

 In short: M31 and the Milky Way will merge into one great elliptical galaxy; M32 will likely become part of its core, while M110 will be torn apart and assimilated into its halo.

Messier 71, the easy to miss Globular Star Cluster.

 

The Globular Star Cluster Messier 71. Data Credit: PIRATE robotic telescope, BVR filters. Mount Teide, Tenerife. telescope.org. Open Observatories, Open University. Image Credit: Kurt Thrust at the JPO.

" Messier 71, sits in the  small constellation Sagitta the arrow. This area of the sky is associated with the plane of the Milky Way's disc and is literally awash with stars when viewed with binoculars or a widefield telescope. Messier 71 being a small globular cluster, is therefore easy to miss within this plethora of stars. As I processed the data and watched the above image materialise, I  was amazed at how many stars I could see!" - Kurt Thrust current Director of the Jodrell Plank Observatory.

A Comparative Report on the Globular Cluster Messier 71

Messier 71 (M71), located in the small constellation Sagitta, is one of the more unusual globular clusters in the Messier catalogue. At a distance of roughly 13,000 light-years, it appears as a loose, irregular grouping of stars through modest telescopes, and for much of the 19th and 20th centuries it was debated whether M71 was in fact a globular or a rich open cluster. Advances in stellar photometry and spectroscopy have since clarified its nature: M71 is a genuine globular cluster, though a relatively low-mass, metal-rich, and loosely concentrated one. Comparison with the more archetypal clusters Messier 13 (M13), Messier 3 (M3), and Messier 4 (M4) underscores the peculiarities of M71.

Messier 13, the “Great Hercules Cluster,” is perhaps the best-known northern globular cluster. It contains several hundred thousand stars in a compact halo over 140 light-years across, with a dense, bright core that exemplifies the globular class. By contrast, M71 contains perhaps only 20,000–50,000 stars spread across a mere 27 light-years. Its lower concentration and modest size explain why early observers mistook it for an open cluster. Whereas M13 presents a dazzling display of densely packed stars and exhibits a well-defined horizontal branch, M71 has only a stubby red giant branch and no extended blue horizontal branch, making its stellar population appear more subdued.

Messier 3 provides another instructive comparison. Situated in Canes Venatici, M3 is among the richest and most extensively studied globular clusters, hosting over half a million stars and more than 200 known variables, including numerous RR Lyrae stars. Its variable population and prominent horizontal branch have made it a cornerstone for calibrating stellar evolution models. M71, on the other hand, lacks a significant RR Lyrae population and is chemically distinct. Its relatively high metallicity ([Fe/H] ≈ –0.8) is atypical for globular clusters, especially when contrasted with the metal-poor stars of M3. This implies that M71 formed later in the Galactic halo’s history, from interstellar gas already enriched with heavier elements, and therefore represents a younger evolutionary epoch within the globular cluster system.

Messier 4, in Scorpius, provides a comparison from the opposite end of the structural spectrum. Though M4 is one of the closest globular clusters to Earth (about 7,200 light-years), and not especially rich in stars compared to giants like M3 or M13, it nevertheless displays a clear globular morphology with a strong central concentration. M4 is notable for its rich population of evolved stars, a well-populated horizontal branch, and chemical peculiarities linked to multiple stellar generations. In terms of mass and richness, M4 is closer to M71 than are M13 or M3, yet it retains the compact, globular appearance that M71 lacks. The difference lies primarily in concentration: M4 is compact and easily recognisable as a globular cluster, while M71 is diffuse, giving it a hybrid appearance that complicated its classification.

In conclusion, M71 highlights the diversity within the globular cluster family. It lacks the immense stellar density and archetypal morphology of Messier 13, the vast population and chemical simplicity of Messier 3, and even the structural clarity of Messier 4. Instead, it is a relatively loose, metal-rich, and moderately populated globular cluster, whose transitional characteristics blur the distinction between open and globular clusters. Its study provides valuable insight into the chemical enrichment of the Galaxy and the lower-mass limits of globular cluster formation.

Professor G.P.T. Chat visiting astrophysicist at the Jodrell Plank Observatory.

The Wizard of Cepheus NGC 7380

 

NGC 7380 The Wizard Nebula in the constellation Cepheus.
Data Credit: PIRATE robotic telescope, SHO filters. Mount Teide.  Tenerife
telescope.org. Open Observatories, Open University.
Image Credit Pip Stakkert at the JPO.

Annotated version of the image. Credit: astrometry.net.

" Pip has taken his own view on the final colours used in this narrow band image. The original data was captured with SHO filters which were mapped to RGB. Hydrogen alpha emission is particularly strong in NGC7380 and therefore 'green' predominates. Pip has adjusted the colour intensity to bring out the 'red' (Sulphur ll) and  blue (Oxygen lll) datas".

I should like to thank Alan Waffles and Waffles Construction Ltd for coming at short notice, to batten down one of the rooves at the JPO, prior to the arrival of high winds and heavy rain. In the event, the storm  wasn't as bad as was predicted and no damage was sustained".- Joel Cairo CEO of the Jodrell Plank Observatory.

" I asked Karl Segin, the JPO's outreach officer and Professor G.P.T Chat our visiting astrophysicist, to put together a brief description of the Wizard Nebula. I hope, like me, you find this enigmatic object interesting" - Kurt Thrust current Director of the Jodrell Plank Observatory.

 NGC 7380: The Wizard Nebula

NGC 7380, commonly referred to as the Wizard Nebula, is a young open star cluster surrounded by an extensive emission nebula. It is located in the constellation Cepheus, at an estimated distance of about 7,200 light-years from Earth. The nebula spans approximately 100 light-years across, making it a prominent star-forming region visible in long-exposure astrophotography. Its popular name arises from the resemblance of the illuminated gas clouds to a robed, wizard-like figure when viewed in visible light images.

The central feature of NGC 7380 is the open star cluster, cataloged by Caroline Herschel in 1787 and later added to William Herschel’s general catalog. This cluster is only a few million years old and contains a rich population of hot, massive O-type and B-type stars, whose strong ultraviolet radiation energizes the surrounding hydrogen gas. The nebula itself is classified as an H II region, a vast cloud of ionized hydrogen where new stars are actively forming.

The process that created the Wizard Nebula follows the standard sequence of stellar nursery evolution. A large molecular cloud of hydrogen and trace elements began to collapse under the influence of its own gravity. Local density enhancements triggered pockets of rapid star formation. As the most massive stars ignited nuclear fusion in their cores, they released intense radiation and powerful stellar winds. This feedback carved cavities in the surrounding cloud, compressing some regions while dispersing others. The result is the sculpted appearance of bright ridges, dark dust lanes, and filamentary structures that give the nebula its dramatic shape.

Embedded within the nebula are protostars and young stellar objects still accreting matter from their natal environment. Observations in infrared wavelengths, which can penetrate the obscuring dust, have revealed numerous stars still in their formative stages. Some of these may eventually join the cluster, while others will disperse as the nebula continues to evolve.

The fate of NGC 7380 will be shaped by its most massive stars. Within a few million years, these stars will end their lives as supernovae, enriching the interstellar medium with heavy elements and possibly triggering further rounds of star formation in the region. Over time, the gas and dust of the Wizard Nebula will disperse into the wider galaxy, leaving behind the open cluster, which itself will gradually lose cohesion due to gravitational interactions.

Today, NGC 7380 is an object of great interest to both professional astronomers and astrophotographers. It provides a natural laboratory for studying the physics of star formation, stellar feedback, and nebular evolution. Its striking appearance, combined with its role as an active stellar nursery, makes the Wizard Nebula one of the most evocative examples of the dynamic processes shaping our Milky Way galaxy.

The Sun today - 07_09_2025

 

The Solar photosphere captured in white light
using - the JPO's 66mm.Altair Lightwave ED refractor, A Baader safety film objective mounted filter, a QHY5lll462c video camera with stacked UV-IR filter and green light filter. All on a Star Adventurer EQ mount.

"The JPO team was all out today getting kit organised for imaging the eclipsed Moon tonight as it rises above the North Sea horizon from Pakefield Cliffs. Sadly, as the day has gone by the clouds have rolled in and the chances of seeing anything of the eclipse tonight appears to be remote. 

Anyway the clouds did stay away long enough  for Kurt to capture some photons of our nearest and dearest star, 'The Sun'.

We certainly captured a lot of sunspots in the two x 1 minute video clips we took on the day.

We tried, for the first time, using a green filter stacked with our usual UV-IR filter as we had been advised that this can help to resolve more sunspot detail. We think this was the case but a red filter similarly stacked is better for 'show-casing' faculae.

Just take a moment to look at the above image and take in that the Sun's diameter (at the level of the photosphere) is 1.39 million km. By comparison the Earth's diameter measured at the Equator is just 12,760 km. The Sunspots appear tiny in the image but in reality could swallow the Earth whole"

The Solar Photosphere and current Solar Activity

• The photosphere is the Sun’s visible surface—the layer that emits most of the light we see—spanning just 100–400 km thick, with an effective temperature near 5,772 K 
• In this layer, convection emerges as a granular texture - if you look carefully at the above image you can see the granulation:
• Granules—tiny, boiling convection cells—are around 1,500 km in diameter, lasting up to 15–20 minutes 
• .Larger supergranules span up to 30,000 km and last about 24 hours, driving magnetic field flows 
• The photosphere’s granulation drives the movement and emergence of magnetic fields that define sunspots and active regions.

Sunspots & Magnetic Suppression

• Sunspots are cooler (~3,500 K vs. ~6,000 K of surrounding photosphere) due to intense magnetic fields that inhibit convection, appearing dark 
• These strong magnetic structures form the roots of magnetic loops that extend into the chromosphere and corona, often associated with solar flares and energetic events 

Current Solar Activity (Summer 2025)

• As of now, the Sun is in Solar Cycle 25, which reached its maximum sunspot activity around late 2024, with numbers around 160 for smoothed monthly peaks 
• .Recent measurement show sunspot number around 108, with new active regions emerging and moderately elevated 10.7 cm radio flux (~146 sfu) 
• However, activity is gradually declining from the peak, with solar flux levels about half of the cycle’s peak by mid-2025 
• .Daily sunspot counts have varied—ranging between ~130–154 in early August 2025"

-Karl Segin outreach coordinator at the Jodrell Plank Observatory.

The stars of the Summer Triangle asterism

The stars of the Summer Triangle: Deneb, Vega and Altair.
All images and spectroscopy captured and processed
by Kurt Thrust at the Jodrell Plank Observatory

" Kurt asked our visiting astrophysicist, Professor G.P.T Chat, to provide some features to look for in the above spectral line profiles and the stellar physics behind them". - Joel Cairo CEO of the JPO.

" An asterism is a recognizable pattern of bright stars in the sky. It may be formed from some of the brighter stars in a constellation, for example the Plough, which includes some of the stars of Ursa Major the Great Bear or a recognizable pattern of bright stars from several constellations, as is demonstrated by the Summer Triangle,which is comprised from the three alpha stars Deneb (Cygnus), Vega (Lyra) and Altair (Aquila). - Karl Segin outreach officer at the JPO.

Big picture

All three are A-type, blue-white stars, so they share strong hydrogen Balmer absorption and relatively sparse molecular features.

They differ mainly in luminosity class and rotation, which change how those same lines look: Deneb is a supergiant (Ia), Vega a near-textbook A0 main-sequence star (V), and Altair a late-A dwarf (A7 V) and extreme rapid rotator.

Where they sit on the HR diagram

Star Spectral type Luminosity class Evolutionary state

Deneb (α Cyg) ~A2 Ia (luminous supergiant) Massive star evolving off the main sequence; on its way through/around the supergiant phases

Vega (α Lyr) A0 V (dwarf) Middle-age main-sequence star, H-burning

Altair (α Aql) A7 V (dwarf) Main-sequence star; very fast rotator (oblate, gravity-darkened)

What your low-res spectra should show

Hydrogen Balmer lines (Hα, Hβ, Hγ, …)

Strongest near A0 → Vega should show the deepest Balmer absorption.

Altair (A7): Balmer lines still strong, but shallower than Vega; metal lines begin to stand out more.

Deneb (A2 Ia): Balmer lines are strong but shaped by low surface gravity—you may notice broad wings with comparatively narrow cores, and in some epochs wind effects (subtle emission infilling or weak P-Cygni signatures in Hα) even at low resolution.

Metal lines (Ca II K at 393.3 nm, Mg II ~448.1 nm, Fe II blends)

Altair: As the latest-type of the three, it should show relatively stronger metal lines than Vega.

Vega: Cleaner A0 spectrum—metals present but less prominent than in Altair; it’s also a mild metallicity-peculiar standard, so don’t be surprised if some metal features look a tad weaker than “textbook.”

Deneb: Despite being only slightly later than Vega by type, the supergiant’s low gravity enhances certain ionized metal lines (e.g., Fe II, Si II) and can make them more conspicuous than in Vega.

Line widths & shapes

Altair rotates extremely fast (period ~9–10 h), so its absorption lines are noticeably broadened even at low resolution.

Vega is also a rapid rotator but seen nearly pole-on, so its projected line broadening is modest—lines look crisper than Altair’s.

Deneb has low gravity and stellar winds; expect less rotational broadening, but broader Balmer wings and occasional wind-affected Hα profiles.

Continuum slope & reddening

Deneb is thousands of light-years away; interstellar reddening can tilt its continuum redward compared with nearby Vega (25 ly) and Altair (17 ly). If the data reduction didn’t fully de-redden Deneb, its spectrum may look slightly warmer/redder than its type alone would suggest.

Physical contrasts that drive those spectral looks

Temperature (rough): Vega ~9,600 K (hottest), Deneb ~8,500 K, Altair ~7,500 K on average (equator cooler than poles from gravity darkening).

⇒ Explains: Vega’s strongest Balmer, Altair’s stronger metal lines, Deneb’s A-type look despite being a supergiant.

Surface gravity (log g): Deneb is very low (supergiant), Vega/Altair are higher (dwarfs).

⇒ Low gravity in Deneb = narrower cores, extended Balmer wings, and stronger ionized metal lines than you’d expect for a dwarf at similar temperature.

Rotation: Altair’s v sin i is huge → rotational broadening across many lines; Vega rotates fast intrinsically but looks sharper because we see it nearly pole-on; Deneb’s spectrum is dominated more by wind + low gravity than rotation.

Luminosity & radius: Deneb is enormously luminous (hundreds of thousands L☉) with a radius of hundreds of R☉; Vega (~40 L☉, ~2.4 R☉) and Altair (~10–12 L☉, ~1.7–2 R☉) are compact by comparison.

⇒ Deneb’s wind features and low-g line morphologies vs. the neat, pressure-broadened dwarf lines in Vega/Altair.

Environments: Vega hosts a well-known debris disk (you won’t see the disk in the spectrum, but it’s part of its story). Altair doesn’t show a comparable far-IR excess. Deneb has a stellar wind and slight α Cygni-type variability, which can subtly change Hα over time.

Quick “at a glance” checklist for the spectral profiles

Deepest Balmer lines? → Vega (A0 V).

Broadened lines overall? → Altair (rapid rotation).

Balmer wings + possible Hα infill, stronger Fe II/Si II for an A-star? → Deneb (A-supergiant, wind + low gravity).

More prominent Ca II K & other metal lines vs Vega? → Altair (later A-type).

Continuum looks a bit redder than expected? → Likely Deneb (distance + interstellar reddening

Epsilon Lyrae 1 and 2

 

Epsilon Lyrae the multiple star system.
Data Credit: PIRATE robotic telescope (Clear and BVR filters).
telescope.org, Open Observatories, Open University.
Image Credit: Kurt Thrust.

"In a dull moment at the Observatory, the JPO Team fell into conversation about the famous double double star, Epsilon 1 and 2, in the constellation Lyra.No one was sure as to whether they had seen the gravitationally bound stellar system through a telescope eyepiece which resolved the target into four stars. Kurt thought that he had once achieved this with the JPO's 127mm refractor at high magnification but if he had it was so long ago that he could not be sure. We looked through the JPO's extensive archive of images but could find none relating to Epsilon Lyrae. As an afterthought, Kurt programmed the PIRATE telescope to capture an image. Clearly the large aperture PIRATE robotic telescope on Mount Teide had sufficient aperture but insufficient magnification to split the star system into four separate stars". - Joel Cairo CEO of the Jodrell Plank Observatory.

" Joel asked me to provide the following overview for the Epsilon Lyrae star system:

Epsilon Lyrae: The Double Double

Situated near the bright star Vega in the constellation Lyra, Epsilon Lyrae is among the best-known multiple star systems in the northern sky. To the unaided eye, it appears as a single faint star of about fourth magnitude, but through even a modest pair of binoculars it is revealed as a close double — two nearly equal stars separated by about 208 arcseconds. These two components are traditionally labeled ε¹ Lyrae (the western pair) and ε² Lyrae (the eastern pair).

What makes Epsilon Lyrae remarkable is that each of these stars is itself a tight binary. Thus, the system has earned the nickname the Double Double. Through a telescope of about 100 mm (4 inches) aperture under steady seeing, each component can be resolved into two stars. The separations are small:

ε¹ Lyrae (STF 2382) splits into a pair of magnitude 5.1 and 6.1 stars, separated by only 2.6 arcseconds.

ε² Lyrae (STF 2383) splits into a slightly wider pair of magnitude 5.4 and 5.5 stars, with a separation of 2.3 arcseconds.

Both pairs orbit each other over timescales of centuries, and the wider ε¹–ε² pairing is gravitationally bound, though the orbital period is measured in tens of thousands of years. The geometry of the system gives observers a striking contrast: ε¹’s stars are aligned roughly north-south, while ε²’s pair is oriented nearly east-west. This nearly orthogonal arrangement makes the system especially pleasing to amateur astronomers who succeed in splitting all four stars.

From a physical standpoint, the Epsilon Lyrae stars are main-sequence A-type stars, somewhat hotter and more massive than the Sun, shining white due to their surface temperatures of around 8,000–9,000 K. They lie at a distance of about 162 light-years (49.6 parsecs).

In observational astronomy, Epsilon Lyrae is often used as a test of both atmospheric seeing and optical resolution. Smaller telescopes may split the wide pair (ε¹ vs ε²), but only instruments of sufficient aperture and magnification under steady skies will reveal the close binaries that make the system a true Double Double". - Professor G.P.T Chat visiting astrophysicist at the Jodrell Plank Observatory.