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| NGC410 Group PIRATE robotic telescope. Data Credit: telescope.org, Open Observatories, Open University. Image Credit: Pip Stakkert Jodrell Plank Observatory. |
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| First Crop of the NGC410 Group |
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| Second Crop of the NGC410 Group |
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| Annotated version of the second crop image. Credits: astrometry. net and Stellarium + |
" When you have a large aperture telescope, located high on a dormant volcano, above the clouds, peering through less of the Earth's dynamic and murky atmosphere and away from light pollution, you can obtain excellent data which can be processed to show distant and faint astronomical objects. The PIRATE and COAST robotic telescopes on Mount Teide, Tenerife certainly fit this bill. The above images show what can be seen as the original footprint of the night sky on the Pisces, Cygnus border, captured with the PIRATE telescope, has been cropped once and then twice by Pip Stakkert at the Jodrell Plank Observatory. The image shows many galaxies and galaxy groups just on the edge of visibility in the final crop. In particular PGC 4234 is just the largest of a group of galaxies which have magnitudes of 15 or more. What is obvious from this image of just a tiny part of the sky, is how mind boggling huge the cosmos is and how many galaxies and stars abound. Our good friend, Prof G.P.T Chat, estimates that in the Galaxies shown in the above image (NGC 407, NGC 408, NGC 410, NGC 414A, NGC 414B, PGC 4234, and PGC 4206 ) there are some 650 to 700 billion stars. Of this total, there are probably some 450 billion stars in NGC 410 alone "! - Kurt Thrust current Director of the Jodrell Plank Observatory.
Comparative Study of Galaxies in the Constellation Pisces by Professor G.P.T Chat (visiting astrophysicist) and Kurt Thrust
This report presents a comparative analysis of seven galaxies located in the constellation Pisces: NGC 407, NGC 408, NGC 410, NGC 414A, NGC 414B, PGC 4234, and PGC 4206. The study examines their morphological type, apparent size, distance, luminosity, spectral characteristics, and stellar population age, with the goal of identifying similarities and differences in their evolutionary status and galactic environments.
Morphological Classification and Structure
The sample includes a range of morphological types, from elliptical and lenticular to actively star-forming spiral galaxies. NGC 410, the most prominent member of this group, is classified as a large elliptical galaxy (E), possibly cD-type, typical of galaxies found at the centers of groups or clusters. It exhibits a smooth, rounded structure with an extended halo.
In contrast, NGC 407 is an edge-on lenticular or early-type spiral galaxy (S0/a), characterized by a thin disk and little to no visible spiral structure. Similarly, NGC 414A and NGC 414B form a compact galactic pair, both classified as lenticular (S0) or elliptical/lenticular hybrids (E/S0). These galaxies show minimal disk structure and are likely passively evolving.
NGC 408 is somewhat of an outlier in this group. Though not as well-characterized morphologically, it appears to be a late-type spiral galaxy, likely of Sc-type or later, due to its ongoing star formation and detection of an ultraluminous X-ray source (ULX). This implies the presence of massive, young stellar populations.
Size and Scale
In terms of angular size, NGC 410 is the largest in the group, spanning approximately 2.4 arcminutes by 1.3 arcminutes, which corresponds to a physical size of about 170,000 light-years at its estimated distance. NGC 407 is slightly smaller, measuring about 1.7 by 0.4 arcminutes, with a thinner, disk-like appearance due to its edge-on orientation. The NGC 414 pair is more compact, with each component contributing to a combined angular size of approximately 0.8 arcminutes, translating to a physical size of roughly 50,000 light-years.
While NGC 408 lacks detailed size measurements, its star-forming nature suggests it is a moderately sized spiral galaxy, possibly comparable to the Milky Way in extent.
Distance and Redshift
The galaxies in this study lie at similar redshifts, ranging from z ≈ 0.01578 to z ≈ 0.01859, corresponding to distances of approximately 210 to 250 million light-years (or 64 to 77 Mpc). Specifically, NGC 414A/B are the closest, at around 210 million light-years, followed by NGC 410 at 240 million light-years, and NGC 407 slightly farther at 250 million light-years. Although a precise redshift for NGC 408 is not readily available, it is likely to be at a comparable distance, given its spatial proximity and grouping.
It is worth noting that PGC 4234 and PGC 4206 are catalog designations equivalent to NGC 410 and NGC 407, respectively, and therefore share identical properties.
Luminosity and Spectral Properties
NGC 410 is the brightest galaxy in this group, with an apparent visual magnitude of 12.5. Spectral studies reveal it to be a composite LINER/H II galaxy, indicating low-level nuclear activity possibly powered by weak AGN processes, as well as localized star formation. Its spectral profile includes weak emission lines typical of low-ionization nuclear emission-line regions (LINERs) and ionized gas from H II regions.
NGC 407, with a visual magnitude of 14.3, also exhibits features consistent with a low-activity galactic nucleus, possibly LINER-like, although detailed spectral data are limited. NGC 414A and 414B are slightly fainter, with a combined magnitude around 14.5, and show little evidence of active star formation or nuclear activity, consistent with their lenticular morphology.
NGC 408, while less luminous in optical bands, is notable for hosting a ULX (ultraluminous X-ray) source emitting at approximately 3.4 × 10³⁹ erg/s. This is indicative of high-mass X-ray binaries or possible intermediate-mass black holes, commonly found in regions of intense star formation. The galaxy’s star formation rate is estimated at about 4.5 solar masses per year, supporting the presence of a younger, actively evolving stellar population.
Stellar Population and Age
Stellar age estimates across this group generally reflect the galaxies’ morphological types. NGC 410, as a massive elliptical galaxy, is dominated by an old stellar population, with most stars likely formed over 10 billion years ago, although the presence of weak H II emission suggests some intermediate-age components (~1–3 billion years) in the nucleus.
NGC 407 and NGC 414A/B, being lenticular galaxies, also contain predominantly older stars, consistent with passive evolution and little to no ongoing star formation. These systems likely ceased significant star formation several billion years ago and now exhibit red, evolved stellar populations.
NGC 408, by contrast, contains young stellar populations, particularly in regions associated with the observed ULX. The age of these populations is likely less than 100 million years, indicating that the galaxy is still actively forming stars, unlike the others in this sample.
Conclusions and Scientific Context
This comparative study highlights the diversity of galactic properties within a relatively small section of the Pisces constellation. NGC 410 stands out as a giant elliptical galaxy with modest nuclear activity and a dominant old stellar population. NGC 407 and the NGC 414 pair represent passively evolving lenticular systems, consistent with aging stellar populations and little gas content. In contrast, NGC 408 displays signs of active galactic evolution, with high star formation rates and energetic X-ray sources that set it apart from the rest.
Although all galaxies lie at similar distances, suggesting they may belong to related local structures or loose groups, their internal dynamics and star formation histories vary significantly. Further high-resolution imaging and spectroscopic surveys would help refine stellar age distributions, gas content, and environmental interactions—particularly for less studied systems like NGC 408 and the 414 pair.
In summary, this group of Pisces galaxies exemplifies the range of evolutionary pathways observed in the local universe, from quiescent elliptical systems to actively star-forming spirals, offering valuable insight into the lifecycle of galaxies across cosmic time.
Summary Table
| Galaxy | Type | Apparent Size (′) | Redshift / Velocity | Distance (ly) | Luminosity & Spectra | Age Estimate (stellar pop.) |
|---|---|---|---|---|---|---|
| NGC 407 | S0/a (edge‑on lenticular/spiral) Wikipedia+4Wikipedia+4Wikipedia+4 | 1.7′ × 0.4′ | z ≈ 0.01859; 5,573 km/s Wikipedia | ≈ 250 million ly (≈75 Mpc) | m_V ≈ 14.3; intermediate activity, likely LINER-like | Intermediate to old bulge (~1–10 Gyr typical) |
| NGC 408 | Spiral (likely Sc‑type) (limited data) | — | (No direct redshift found) | Poorly characterized; likely similar distance ( | Host of ULX X‑ray source; star‑forming (~4.5 M_⊙/yr) arXiv | Active star formation implies young (<100 Myr) populations in parts |
| NGC 410 | Elliptical (E), cD/LINER‑H II composite de.wikipedia.orgWikipedia | 2.4′ × 1.3′ | z ≈ 0.01766; ~5,294 km/s WikipediaGo-Astronomy.com | ~240 million ly (~73 Mpc) de.wikipedia.org | m_V ≈ 12.5; contains LINER/H II regions, some star formation regions de.wikipedia.orgGo-Astronomy.com | Dominated by old stellar populations, though nuclear region may include ~10⁸–10⁹ yr intermediate populations |
| NGC 414A / 414B | A: S0, B: E/S0 within NGC 414 pair Wikipedia | Combined ~0.8′ – likely individual ~0.4′ | z ≈ 0.01578; 4,730 km/s Wikipedia | ≈ 210 million ly (~64 Mpc) | m_V ≈ 14.5; typical lenticular spectra, likely no strong emission lines | Generally old (~few Gyr), low ongoing star formation |
| PGC 4234 | Equivalent to NGC 410 (PGC 4224) de.wikipedia.orgWikipedia | same as above | same as NGC 410 | same ~240 million ly | same | same |
| PGC 4206 | Equivalent to NGC 407 (PGC 4190) Wikipedia | same as NGC 407 | same as NGC 407 | ~250 million ly | same | same |
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