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Stephan's Quintet, (HCG 92, Arp 319), NGC 7320 Galaxy Group, Pegasus
This tight visual grouping of five galaxies was discovered in 1877 by Edouard Stephan at the Marseilles Observatory with the revolutionary 80 cm Foucault reflector, which was among the first to use a mirror of silvered glass, instead of speculum metal. The Quintet is the first compact group of galaxies ever documented. It has been carefully studied by numerous observatories ever since because it shows three galaxies in the process of merging, NGC7318-A, NGC7318-B, and NGC7319. All three appear to be barred spiral galaxies, severely distorted by tidal interactions. All display elongated and disrupted spiral arms, faint tidal tails of stars and gas drawn out from the galaxies into intergalactic space, and numerous bright blue regions of countless new stars ignited by gravitational perturbations of hydrogen clouds. Hubble's multi-band images in visible and infrared light reveal stellar populations of several age groups, indicating that starburst activity occurred in different epochs over hundreds of millions of years. In the long run, after billions of years, the three galaxies are destined to merge into a single giant elliptical galaxy. Based on their redshifts, and assuming Hubble Flow, the three galaxies lie at light travel distances between 267 and 312 million light years. However, they are probably much closer together. Due to strong gravitational interaction, they must have high peculiar velocities through space, which renders their distance estimates based on Hubble Flow unreliable.
www.cloudynights.com/articles/cat/articles/basic-extragal...
The fourth galaxy in the group is a modest elliptical galaxy, NGC 7317, gravitationally bound to its companions, but so far morphologically unaffected. These four galaxies are also gravitationally bound to the distant members of the Deer Lick Group, from which they are separated by only 35 arcmin.
www.cloudynights.com/topic/802766-ngc-7331-deer-lick-gala...
The most prominent galaxy in Stephan's Quintet is NGC 7320, a bright dwarf unbarred spiral which is actually 8 times closer than the other members of the visual grouping, and is gravitationally unbound to them. Based on its measurable properties (redshift, apparent magnitude, and angular size), it lies at a light travel distance of 36.4 Mly, receding at 706 km/s due to Hubble Flow (the expansion of space). Its diameter is only about 25,000 ly, five times smaller than the Milky Way's, and absolute magnitude some twenty times fainter. Blue color indicates a high star formation rate and a profusion of large, young, and very hot stars.
The most distant galaxy in the field is 2MFGC 17021, a large edge-on spiral, approximately the same size as the Milky Way, but about twice as bright. It is 784 Mly distant, receding at 17,113 km/s.
Image Details:
-Remote Takahashi TOA 150 x 1105 mm
-Paramount GT GEM
-25 x 300 sec subs, OSC, 2x drizzle, 30% linear crop
-Software: DSS, XnView, StarTools v 1.3 and 1.7, Cosmological Calculator v 2
On August 17, 2025, on the 16th anniversary of the start of my study of astronomy by self-education, I made calculations of the sky coordinates and requested shooting on remote telescopes (with parameters according to my calculations, for example, shutter speeds and number of images) to search for new astronomical objects. When I received and viewed one of the series of images, I found a star in them, which, upon checking in various information sources, turned out to be an already known supernova, but even such a find is unusual for me, because in several years of searching in images, I did not come across even a single known supernova.
When checking 5 photographs (of the sky region in the constellation Pisces) with exposures of 300 seconds taken on this date with another remote telescope, the 0.51-m f/6.8 reflector T59 of iTelescope.Net, which is located at the Siding Spring Observatory in Australia, at the very edge of the images (only 12 arcseconds from the edges of the frames!) I saw a relatively faint star (only about +20 mag), which was absent from the archival photographs: only the galaxy SDSS J004819.14+075856.8 was visible in them nearby. I assumed it was a supernova in this galaxy, and when I checked, this star was unknown, so I measured its position and brightness, then sent the information to the Transient Name Server (as of January 1, 2016 the Transient Name Server (TNS) is the official IAU mechanism for reporting new astronomical transients such as supernova candidates) with the status as a possible supernova, and it was published there: www.wis-tns.org/object/2025umq with temporary designation AT 2025umq, and as PSN J00481888+0759006 on the CBAT TOCP www.cbat.eps.harvard.edu/unconf/followups/J00481888+07590...
On August 19 I made remote observations of this star with a two-metre-aperture robotic Liverpool Telescope (LT — on the Canary island of La Palma) to confirm the reality of the object, and it worked out, I also made new measurements of its position and brightness (to refine them): about +20.3 mag. On August 23 and 24 I additionally made photometric observations with the LT to get more such information about this star. I am attaching a photo (color) for August 24 (stacked 3x60 sec. with g’, r’ and i’ filters, 9 frames in total).
On August 20, according to my calculations and request, the spectrum of this star was obtained at the Liverpool Telescope, as a result of its analysis, this star was classified as a fading Type Ia supernova at redshift of 0.159 in the galaxy SDSS J004819.14+075856.8, with assignment it the designation SN 2025umq. On August 27, the corresponding ATel #17361 www.astronomerstelegram.org/?read=17361 was published on the website «The Astronomer's Telegram» about the discovery, photometry and classification of this supernova with my name as the first author.
I will add that later I saw in one of the scientific sources on the Internet that this supernova was previously detected by ZTF sky survey (the light curve shows a maximum brightness of about +20 mag around August 10, and the first detection was on July 25), but for some reason information about it was not sent to the TNS, so I am its official discoverer.
It is important that this is the first supernova discovered by me personally (in the images obtained - at my request - from a remote telescope), because earlier I discovered two supernovae SN 2022bsi and SN 2022jhn only in the images of the CRTS sky survey, participating in the supernova search project, so I am the first co-author of those discoveries. In addition, I consider it's luck that supernova SN 2025umq was not outside the boundaries of the images, because it was very close near the edges of the frames. Also note that those two supernovae were much closer (at redshifts of 0.0369 and 0.013) to our galaxy, while this supernova is distant enough: it has a redshift of 0.159, which means it is more than 2 billion light years away, so it was a big luck that I, an amateur astronomer, was able to discover so low brightness supernova! I should add that usually such faint supernovae are rarely classified using the Liverpool Telescope (because too long exposures are needed to obtain a good signal-to-noise ratio, so it is more practical to use larger telescopes, but I did not have the opportunity to use a larger telescope to study this supernova, so I tried to do it at the Liverpool Telescope), but in this case it was possible to do so with the LT - due to the sufficient distance of this supernova from the center of the host galaxy.
Now I am the discoverer (only on the basis of self-education) of 82 variable stars, 10 planetary nebula candidates (and co-author of discovery of 5), 3 supernovae (two co-authored and one personally), 4 probably physical binaries pairs of stars, 3 novae in M31; 3 transients (possible supernovae) and 8 asteroids; author of scientific papers in astronomy, which were published in scientific journals (including peer-reviewed) and co-author of the papers, for example, the most recent «GOTO065054+593624: An 8.5 mag amplitude dwarf nova identified in real time via Kilonova Seekers» was published doi.org/10.1051/0004-6361/202553823 in Astronomy & Astrophysics (A&A). I have given online presentations during several international conferences in astronomy, for example, e-Poster during the XXXIst General Assembly of the International Astronomical Union (IAUGA 2022), my paper "The contribution of the modern amateur astronomer to the science of astronomy" (based on this my e-Poster) was published arxiv.org/abs/2212.12543 in arXiv.
Better resolution: nicolasillustrations.com/project/ngc7497-lrgb
NGC 7497 is a barred spiral galaxy located in the constellation Pegasus. Its velocity relative to the cosmic microwave background corresponds to a Hubble distance of 19.8 ± 1.4 Mpc (approximately 64.6 million light-years). Discovered by the German-British astronomer William Herschel in 1784, it was also observed by the British astronomer John Herschel in 1825.
NGC 7497 has a luminosity class of VI and a broad HI line. With a surface brightness of 14.38 mag/arcsec², it is categorized as a low surface brightness galaxy (LSB), where LSB galaxies, of diffuse (D) type, have a surface brightness at least one magnitude fainter than the ambient night sky.
Currently, twenty-two non-redshift-based measurements indicate a distance of 17.864 ± 3.715 Mpc (approximately 58.3 million light-years), which is consistent with Hubble distance values.
During visual observations, this spiral galaxy appears as a faint grayish bar. However, on extended photographic exposures, a different spectacle unfolds. The accumulation of photons reveals that NGC 7497 is, in reality, "captured" in an extensive molecular cloud named LBN 419, listed in Lynds' Catalog of Bright Nebulae, which includes 1791 bright nebulae. Molecular clouds are celestial regions where gas and dust conglomerate, primarily composed of molecular hydrogen (H2). These cold regions also serve as stellar nurseries, where new stars are born. It's worth noting that LBN 419 is actually much closer, located within our own galaxy.
RA 23h 08m 58.9s
DEC +11° 11' 37.2"
SIZE 30.5 x 20.1 arcmin
ORIENTATION Up is 184.4 degrees E of N
CONSTELLATION Pegasus
MAGNITUDE 12.2
DISTANCE 64 million ly
Captured July 2023
Technical Details
Data acquisition: Telescope.Live
Processing: Nicolas ROLLAND
Location: El Sauce Observatory, Rio Hurtado, CHILE
L: 32*300s
R: 32*300s
G: 35*300s
B: 32*300s
Optics: PLANEWAVE CDK24 @ F/6.5
Mount: Mathis MI-1000/1250 with absolute encoders
CCD: QHY 600M Pro
Astrodon LRGB 2GEN
Data from the following proposal is used to create this image:
Establishing HST's Low Redshift Archive of Interacting Systems
All channels: ACS/WFC F606W
North is 13.46° counter-clockwise from up.
Chaos.
Data from the following proposal is used to create this image:
Establishing HST's Low Redshift Archive of Interacting Systems
All channels: ACS/WFC F606W
North is 65.77° clockwise from up.
Release Date: March 10, 2010 - Distant galaxy clusters mysteriously stream at a million miles per hour along a path roughly centered on the southern constellations Centaurus and Hydra. A new study led by Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md., tracks this collective motion -- dubbed the "dark flow" -- to twice the distance originally reported, out to more than 2.5 billion light-years.
Abell 1689, redshift 0.181.
Credit: NASA/Goddard Space Flight Center/Scientific Visualization Studio/ESA/L. Bradley/JHU
To learn more go to:
www.nasa.gov/centers/goddard/news/releases/2010/10-023.html
To see other visualizations related to this story go to:
One of the last of the galaxies I haven't done yet for this proposal. I've been putting it off because it's not as interesting as most of the others. I'm not sure why it was chosen for the survey. Maybe the ever-so-slight spiral structure it might have?
Establishing HST's Low Redshift Archive of Interacting Systems
All Channels: ACS/WFC F606W
North is 56.46° counter-clockwise from up.
Lots of umbrella-like arcs of stars encircling this galaxy. These are possibly the result of a smaller, compact galaxy dropping into the larger one and swishing back and forth several times as it is stretched out into a long, complex orbit, or perhaps many orbits. It's not something I will ever claim to understand in great detail.
Data from the following proposal is used to create this image:
Establishing HST's Low Redshift Archive of Interacting Systems
All channels: ACS/WFC F606W
North is 18.91° clockwise from up.
Field Galaxy NGC 2903, Satellite Galaxy UGC 5086, and Four Quasars, Leo
NGC 2903 is a barred spiral galaxy in the constellation of Leo, first documented by William Herschel in 1784. Although it is bright and fairly large, easily seen in binoculars, it escaped the attention of Charles Messier and his associate Pierre Mechain. On a large scale, NGC 2903 lies within the Virgo Supercluster which includes the Milky Way and Andromeda galaxies. Except for dwarf elliptical galaxy UGC 5086, at a distance of 2 million ly, it has no nearby neighbors, and does not belong to any local galaxy cluster. Such isolated galaxies, undisturbed by gravitational fields of large neighbors, are called "field galaxies", constitute 10-20% of the total galaxy population, and follow different evolutionary pathways than "cluster galaxies". Unaffected by major tidal forces and mergers, large field galaxies are most commonly low-surface-brightness (LSB) spirals with delicate and symmetrical spiral arm structure, and usually manifest low star formation rates (SFR). However, NGC 2903 is far from quiescent. Although its energy output is insufficient to qualify it as an active galactic nucleus (AGN), its nucleus is still bright in all bands, from radio waves to X-rays, suggesting the presence of a central supermassive black hole (SMBH) with polar jets and an accretion disk. Photometric and spectroscopic analysis of the central region reveals increased star formation rates generated by interstellar medium turbulence initiated by radiation pressure and feedback outflows from the central SMBH. The turbulence then extends outward, augmented by stellar winds and supernovae, enhancing new star formation further afield. The distinct blue floccules in the spiral arms represent "OB associations", huge clusters of very hot young stars.
www.cloudynights.com/articles/cat/articles/basic-extragal...
From its measurable properties, using the redshift-independent distance method, it can be calculated that NGC 2903 is about 24 million ly distant, and 98,000 light years in diameter, roughly 30% smaller than the Milky Way, and proportionally less luminous. Several interesting features within the galaxy are marked on the annotated image. Some sources define object NGC 2905 as a bright region south of the nucleus. Opinions differ whether the object is a large collection of stars or a very hot ionized hydrogen (Hii) region. Meanwhile, both NED and SIMBAD extragalactic databases list NGC 2905 simply as a duplicate identifier for the main galaxy. Along the NE perimeter of the galaxy, marked with "S" on the annotated chart, there is evidence of a curved luminous region which does not seem to be a part of the spiral arm. I speculate it may be a small satellite galaxy in the process of merging, stretched into a "stellar stream" by the tidal forces of the main galaxy. Computer models show that stellar streams can persist for billions of years through multiple galactic orbits before they are ultimately dispersed into anonymity. Gaps in stellar streams are thought to be caused by encounters with dark matter overdensities (subhalos) within the galactic halo. In the west quadrant of the galaxy, marked with letter "x" on the annotated image", are located two ultra-luminous X-ray sources (ULX). Such objects can be associated with intermediate-mass black holes (IMBH), and may emit optical transients during the periods of more active accretion.
www.cloudynights.com/articles/cat/articles/basic-extragal...
Numerous distant galaxies are visible in the background, many of which have no identifier. Of the more prominent ones, the most formidable is SDSS J093239.53+214555.7, a hyperluminous giant galaxy, at least 160,000 ly in diameter, lying at a distance around 3.2 billion ly. Near the threshold of the limiting magnitude can be seen four quasars (QSOs) listed in the chart below. The most luminous one is QSO B0929+2128, nearly 2,500 times brighter than the Miky Way.The most remote is QSO B0929+218 whose light travelled 11.1 billion years before reching us. When its photons were emitted, the quasar was receding at 255,249 km/s from the past location of our Galaxy (relativistic or redshift recession velocity). In the present epoch, it lies at a "comoving = proper distance" of 19.4 billion ly, receding at a superluminal "proper recession velocity" of 416,815 km/s. The quasar is now located well beyond the "cosmic event horizon". Since the space between us is expanding faster than its light is moving toward us, the photons it is presently emitting can never reach us.
Image details:
-Remote Takahashi TOA 150 x 1105mm, Paramount GT GEM
-27 x 300 sec subs, OSC, 2x drizzle, 60% linear crop
-Software: DSS, XnView, StarNet++ v2, StarTools v 1.3 and 1.8
Arp 130 consists of MCG+03-01-016 (PGC 178, VV 263b and others) the spiral that looks like it is interacting with IC 5378 (PGC 177, UGC 1, VV 263/a), the elliptical below it. Redshift data suggests that these galaxies are at least 20 million light-years away from each other so they just look close from our vantage point. Arp has this one in his “E and E-like galaxies – close to and perturbing spirals.” These are located in Pegasus approximately three degrees from Algenib.
The other odd irregular galaxy on the right side is IC 5377 (PGC 156, UGC 12918 and others).
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 10x300s – 50 minutes each – binned 2x2
390 minutes total exposure – 6 hours 30 minutes
Imaged August 26th and 31st and September 1st, 2019 from Dark Sky New Mexico at Rancho Hidalgo (Animas, New Mexico) with a SBIG STF-8300M on an Astro-Tech AT12RCT at f/8 2432mm.
Data from the following proposal is used to create this image:
Establishing HST's Low Redshift Archive of Interacting Systems
All channels: ACS/WFC F606W
North is 1.81° clockwise from up.
A number of quasars can be found around the Leo Triplet galaxy, NGC 3628. Source numbers for redshift and distances were taken from the paper titled, "NGC 3628: Ejection Activity Associated with Quasars."
NGC5907 (NGC5906, UGC09801), Draco, Knife Edge Galaxy, and Five Quasars
NGC 5907 is a large nearly edge-on spiral galaxy, first documented by W. Herschel in 1788. On a large scale it is one of the brightest members of the small NGC5866 Galaxy Group in the constellation of Draco. Although the designation generally refers to the entire galaxy, it was not until 1850 that George Stoney identified the faint W part of the galaxy obscured by prominent equatorial dust lanes as NGC 5906. According to NED (NASA Extragalactic Database), the galaxy is 12.8 arcmin in angular size and 9.18 (V) in integrated apparent magnitude Other values found in the literature for the visible band magnitude include 11.12, 11.8, and 12.46, which simply appear too low when compared to the object's photographic brightness. Due to its edge-on orientation its integrated apparent magnitude and the calculated absolute magnitude are significantly underestimated for two reasons. First, it presents to the observer a much smaller surface area than a face-on galaxy. And second, much of its starlight is absorbed and scattered by thick layers of gas and dust in the galactic plane. Its redshift of 0.002225 indicates light travel distance of 30.88 Mly, assuming redshift is due exclusively to the expansion of space (Hubble Flow). For redshifts < 0.01, redshift-independent distance measurements, such as the Cepheid method, are generally more accurate because a fraction of the redshift value is due to an object's motion through space. For NGC5907 the median redshift-independent distance value is 14.275 Mpc, or 46.54 Mly.
Based on the measurable properties, we can estimate NGC5907 to be 172,000 ly in diameter, approximately 40% larger and two times brighter than the Milky Way. Its redshift indicates a recession velocity of 666 km/s. Its morphological classification is SAc (or Sc), indicating a spiral galaxy with loosely wound arms and no evidence of a nuclear bar. Considering the galaxy's nearly edge-on presentation with 87.2* inclination to our line of sight, the presence of a bar can not be confidently ruled out because a view of the nucleus is obscured by dust, gas, and luminous matter in the galactic disk. Garcia-Burillo et al. (1997) suggest that anomalies in molecular gas kinematics can be explained by the presence of a stellar bar. The galaxy has a thin disk with a nearly absent central bulge, resulting in a bulge-to-disk luminosity ratio of only 0.05. Prominent equatorial dust lanes extend nearly to the edges of the galactic disk. While there is some controversy about the presence of extraplanar dust, Xilouris et al. (1999) report that the thickness of extraplanar dust is about 10% larger than the thickness of the stellar disk. As indicated by the light blue floccules of hot newborn stars and by the presence of numerous ionized hydrogen (Hii) regions in the galactic disk, the galaxy displays an above average star formation rate (SFR). This was initially perplexing since the galaxy was thought to be an isolated field spiral with no evidence of tidal disruption. However, deep-sky images by R Jay GaBany (2006) revealed a complex interweaved structure of stellar debris surrounding the galaxy, resulting from an accretion event over four billion years ago. Gravitational perturbations caused by this stream explain elevated SFR and the slight warp in its galactic disk.
www.cosmotography.com/images/small_ring_ngc5907.html
Although it is statistically very likely that NGC5907 contains a central supermassive black hole (SMBH), literature search reveals no information regarding detection of radio wave or high energy emissions from the galactic nucleus. If a central SMBH is present, it shows no evidence of active accretion at this time. Nor can a central SMBH be confirmed by spectroscopy and stellar kinematics. Due to the edge-on orientation, the nucleus is obscured in the optical band by equatorial gas, dust, and luminous matter.
The annotated image indicates the position of an ultra-luminous X-ray source (ULX) within the galaxy's disk. The precise nature of these objects is not confidently known. In order of probability, their energy source is explained as accretion around an intermediate mass black hole (IMBH), super-Eddington accretion around a neutron star or large stellar-mass black holes (BH), or beamed emissions from high mass X-ray binary stars. Pintore et al. (2018) reported an X-ray transient event in this ULX implying a flux increase by a factor of >35. They find the event is consistent with a ~30 solar mass black hole accreting at the Eddington limit, or with beamed emissions from an accreting neutron star.
Other objects of interest on the annotated image include an irregular dwarf galaxy LEDA 54419. Its redshift is very similar to that of NGC5907 suggesting the two might be bound. Distinct blue color indicating high SFR further increases the possibility of tidal interaction. Unfortunately, no redshift-independent distance measurements have been made for this galaxy, and their interaction can not be confirmed. A number of remote galaxies lie in the background. Four of these which carry identifiers are located at distances between 1.6 and 1.73 Bly. Another six even more remote galaxy candidates are marked with letter G. The image also includes five identified quasars. Three of these appear brigher than their listed apparent magnitudes. They are marked with the "+" sign on the chart below. Since quasar luminosity depends on its SMBH accretion rate, quasars often manifest variability up to several magnitudes over a period of days to years. The last two quasars on the list have super-luminal recession velocities in the present cosmological epoch. They have crossed the cosmic event horizon, and the light they are presently emitting can never reach us. The most remote of the quasars is SDSS J151538.77+560520.4 at a light travel distance (lookback time) of 10.86 billion light years.
Image details:
-Remote Takahashi TOA 150 x 1105mm, SBIG STF-8300C, Paramount GT GEM
-OSC 32 x 300 sec, 2x drizzle, 50% linear crop
-Software: DSS, XnView, StarNet++ v2, StarTools v1.3 and 1.8, Cosmological Calculator v3
We'd trade away the sky if we thought it would save us.
Data from the following proposal is used to create this image:
Establishing HST's Low Redshift Archive of Interacting Systems
All channels: ACS/WFC F606W
North is 17.62° counter-clockwise from up.
The @redshiftsports Dual-Position seatpost in my @jguillem Orient endurance bike.
I have just posted my impressions and aero position musings on my blog. Find the link here: torstenfrank.wordpress.com/2017/10/27/aero-position-probl...
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Die Redshift Sports Dual-Position Sattelstütze in meinem J.Guillem Orient Endurance Rad.
Ich habe soeben meine Eindrücke und Zeitfahr-Positions-Überlegungen in meinem Blog publiziert. Anbei der Link: torstenfrank.wordpress.com/2017/10/27/aero-position-probl...
Taken with my Pentax 67 with 200mm lens and Ilford HP5 Plus film. Scanned with my Plustek OpticFilm 120
This photo is really just meant to be informative and educational for those that are curious about the Universe, and want to know how things work. As photographers we capture Photons after all, so here is a bit of the Physics behind the light that we love to capture.
This image shows the Electromagnetic Spectrum of light from the Sun, after traveling through Earth's blue Nitrogen rich skies (photographed through a Quantitative Spectroscope).
The nanometer scale in the Spectroscope shows the wavelengths of visible light, that range from 400 nm - 700 nm. Invisible light at shorter wavelengths (beyond violet) include Ultraviolet (UV), X-Ray and Gamma Ray. Longer wavelengths of light (beneath red) include Infrared, Microwave and Radio Waves.
About the Sun:
The Sun is a G-type Main-Sequence Yellow Dwarf (G2V) Star. Through the process of fusion, the Sun burns approximately 600 million tonnes (metric tons) of Hydrogen each second, turning it into 596 million tonnes of Helium. As the Hydrogen nuclei fuse, Photons are emitted, which in short is why the Sun shines (and all the other stars). The Hydrogen Atom is the simplest and most abundant element in the Universe (with only 1 Proton and 1 Electron).
Through the process of fusion, more complex elements are made at different stages of a star's life and death cycle. This is what Carl Sagan meant with one of his well known quotes from Cosmos, “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”
The Sun is roughly 150,000,000 km from Earth. The speed of light is 300,000 km/sec (186,000 miles/sec), which means that the light took just over 8 light-minutes (8 minutes and 26 seconds) to reach the Spectroscope in front of my camera lens.
Here is a very simplistic explanation of Spectroscopy, and how the Electromagnetic Light Spectrum is used in Astrophysics:
This image was photographed through a basic "High School Science Classroom" Quantitative Spectrometer (100 line resolution). With higher resolution Spectrometers on Telescopes, Astronomers can determine what chemical elements Stars and Planets are made of, as each chemical element has a unique light absorption fingerprint, that shows up as dark lines in the spectrum.
The amount that the absorption lines are shifted to red or blue (redshift and blueshift), is due to the Doppler effect and gives an indication if the celestial object is moving towards or away from us, and at what speed. This is how Scientists and Physicists know what the observable Universe is made of, and that the Universe is expanding.
More Info:
en.wikipedia.org/wiki/Spectral_line
en.wikipedia.org/wiki/Fraunhofer_lines
www.space.com/25732-redshift-blueshift.html
science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html
Interested in Science, Physics & Astronomy?
Visit my Flipboard with lots of interesting articles:
flipboard.com/@mheigan/brain-food
Martin
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NGC 4535, Virgo, The Lost Galaxy of Copeland, and Five Quasars
NGC 4535 is a low surface brightness (LSB) barred spiral galaxy in the constellation Virgo, first documented by William Herschel in 1785. Due to its hazy and "ghostly" visual presentation prominent amateur astronomer Leland Copeland named it "The Lost Galaxy" in the 1950s. Based on its median redshift-independent distance measurement of 51.53 Mly, apparent magnitude of 10.32 (g), and angular size of 7.80 arcmin, the galaxy is approximately 116,000 ly in diameter and 90% as bright as the Milky Way. Its redshift of 0.00657 corresponds to a recession velocity of 1,963 km/s, which is in part due to the expansion of space, and in part to its "peculiar velocity" through space relative to us. Its morphological classification is SAB(s)c, indicating an intermediate-barred spiral galaxy without a central ring, and with moderately wound spiral arms. The galaxy is one of the larger members of the Virgo Galaxy Cluster that includes up to 2,000 members. Like most "cluster spirals" it shows evidence of tidal interaction with other members in the form of spiral arm deformation and splitting, gas depletion, and low average star formation rate (SFR) in the current cosmological epoch. The blue floccules in the spiral structure represent "OB Associations", immense clusters of large and very hot young stars. However, unlike in similar galaxies, these are present in relatively low numbers due to gas depletion in the galactic disk. For this reason, NGC 4535 is regarded as a low surface brightness (LSB) galaxy. A number of curved, elongated structures in the disk strongly resemble "stellar streams", or gravitationally stretched remnants of merged dwarf galaxies. Many major galaxies in the Virgo Cluster show evidence of rapid mass assembly through the process of dwarf galaxy accretion.
NGC 4535 has been extensively investigated regarding the presence of a central supermassive black hole (SMBH). Central black holes have been detected in virtually all substantial galaxies studied. Spectroscopic analysis of the central region in the optical band shows evidence of numerous ionized hydrogen (Hii) clouds. These originate from molecular gas clouds ionized by the powerful ultraviolet radiation emanating either from an SMBH accretion disk and/or circumnuclear regions of new star formation. The width of the spectral lines indicates the "velocity dispersion" of luminous matter near the nucleus, which in turn depends on the intensity of the gravitational field generated by the mass in the galactic center. Studies of NGC 4535 refined the understanding of the relationship between the mass and activity of the central SMBH and the evolution of the galaxy within which it resides. For example, this galaxy's gas depletion and current low average star formation rate are in part due to the return of mass momentum and energy from the black hole to the galaxy by the mechanisms of "SMBH outflows" and "radiation pressure" respectively. These processes expel gas and dust from the galaxy, and are explained in more detail in section 40 here:
www.cloudynights.com/articles/cat/articles/basic-extragal...
While NGC 4535 does not have a central starburst ring structure visible in the optical band, it has been one of the major subjects in recent studies on galactic ring formation (Jiayi Sun et al. 2018). Observational evidence reveals a close association between galactic star formation rate (SFR), molecular gas clouds which are the gas reservoir for star formation, and ionized hydrogen (Hii) regions formed when molecular gas is exposed to ionizing ultraviolet radiation from newborn stars. The hydrogen molecule, H2, originating from the big bang, is by far the main component of molecular gas. The second most abundant component is the carbon monoxide molecule, CO, whose constituent atoms were formed during the preceding generations of "stellar nucleosynthesis". Its emission line at the wavelength of 2.6 mm is used in radio-astronomy to map the distribution of galactic molecular gas clouds. While low mass galaxies show faint and scattered CO emissions, massive spiral galaxies exhibit bright, contiguous ring-like emissions within the galactic bulge (Hughes et al. 2013a). These structures, named "Resonance Rings", are thought to accumulate in regions where the outward acting-forces on the molecules balance the centrally-acting gravitational forces. More precisely, resonance rings form where the kinetic energy of gas molecules, defined by the average "velocity dispersion", balances the gravitational potential energy. The evolution of molecular resonance rings also depends on other mechanisms, such as magnetic fields, central SMBH outflows and radiation pressure, and external gravitational effects and matter exchange related to merging or interacting galaxies. In NGC 4535, a resonance ring was detected approximately 1,500 ly from the center. Under favorable circumstances molecular resonance rings evolve into star-forming regions, and eventually become brightly luminous in the visible band.
Derived properties of identified faint objects are listed in the chart on the annotated image. The most remote are five quasars, four of which lie beyond the "cosmic event horizon", as their recession velocities in the present cosmological epoch are superluminal. Two of them, marked with (+) appear significantly brighter than their listed apparent magnitudes. Many quasars are variable up to several magnitudes with periods ranging from days to years, depending on the inflow of matter available for accretion. The most intrinsically luminous object is LBQS 1232+0815, which is nearly 5,000 times brighter than the Milky Way. The most distant quasar is SDSS J123352.16+080527.4 (z = 2.76700), lying at a light travel distance (lookback time) of 11.33 Bly.
Image details:
-Remote Takahashi TOA 150 x 1105 mm
-OSC 36 x 300 sec, (2021 + 2022), 2x drizzle, 40% linear crop, FOV 31x21 arcmin
-Software: DSS, XnView, Starnet++ v2, StarTools 1.3 and 1.8, Cosmological Calculator 3
redshift removals
helping you to come and go
doppler shifts r us
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farnarkling and here we are. This one was tooling along nicely as a mediation on the texture of the filleted avian component of my 'Surfin' Birds' piece. I'd got that more or less to where I wanted to go, but thought that the environment could use a kick of its own to help contrast with the artifact. Mindful of other serendipitous interventions I experimented with the normally mundane "Red-Eye Removal" filter, and...u beaut! A fair bit more digital
The haiku grew out of the "Not An Idle Bone" title as I thought of moving house on a galactic scale, and the "Red" part of "Red-Eye" in a cosmic sense. Christian Doppler, of course, was an Austrian, which as any typographer knows, means he's practically Australian...no worries Herr matey, ta very much!
And it even kinda blips out a little visual pulse from strobing when it scrolls on the screen...wicked! (GRINS) It's rather far out when viewed full screen too.
ESA’s Euclid will examine visible and infrared light from distant galaxies using two scientific instruments on board. These instruments will measure the accurate position and shapes of galaxies in visible light, and their redshift (from which their distance can be derived) in the infrared light. With these data, scientists can construct a 3D map of the distributions of both the galaxies and the dark matter in the Universe. The map will show how large-scale structure evolved over time, tracing the role of dark energy.
The VISible instrument (VIS) takes very sharp images of galaxies over a much larger fraction of sky than would be possible from the ground. These observations will be used to measure the shapes of over a billion galaxies.
As the name suggests, VIS collects visible light. It is sensitive to wavelengths from green (550 nanometres) up to near infrared (900 nm). The instrument uses a mosaic of 36 CCDs (Charge Coupled Devices, a type of camera sensor), each of which contains more than 4000 pixels by 4000 pixels. This gives the detector a total of about 600 megapixels, equivalent to almost seventy 4K resolution screens.
Near-Infrared Spectrometer and Photometer (NISP) is dedicated to making spectroscopic measurements of galaxies, which involves determining how much light they emit per wavelength. This is useful for measuring the galaxies’ redshift, which cosmologists can use to estimate the distance to each galaxy. NISP has the largest field of view for an infrared instrument ever flown in space. The instrument measures near-infrared light (900–2000 nm) using a grid of 16 detectors, each containing more than 2000 by 2000 pixels.
Euclid is ESA’s space telescope designed to explore the dark Universe. The mission will create the largest, most accurate 3D map of the Universe ever produced across 10 billion years of cosmic time. Euclid will explore how the Universe has expanded and how large-scale structure is distributed across space and time, revealing more about the role of gravity and the nature of dark energy and dark matter.
Credits: ESA (acknowledgement: work performed by ATG under contract to ESA), CC BY-SA 3.0 IGO
Mountain due east of Las Vegas on the border of Lake Mead draws in the early red shifted light of morning.
Just uploading a grayscale version of this so I can keep all the observations from this proposition organized better. The color version is here: flic.kr/p/2dqvScX
Establishing HST's Low Redshift Archive of Interacting Systems
All Channels: ACS/WFC F606W
North is 37.73° clockwise from up.
ARP 294, Interacting Galaxies with Stellar Streams, NGC 3786 and NGC 3788, Ursa Major
NGC3786 and NGC3788 are a tight pair of apparently interacting spiral galaxies in the constellation of Ursa Major, first documented by W. Herschel around 1790. They are listed as ARP 294 in the Atlas of Peculiar Galaxies which includes examples of unusual structures found among galaxies. As the chart below indicates, the galaxies are very similar in angular size, around 2.2 arcmin, apparent magnitude of 13.3 (g), and morphological classification as peculiar intermediate spirals with a ring. Their redshift-based distances are 125.4 and 123.8 million light years respectively, suggesting a separation between them of 1.6 Mly. However, redshift-based distance estimates assume that redshift recession is due exclusively to the expansion of space, and do not correct for galaxies' "peculiar velocities" through space. For redshifts less than 0.01, or distances less than 138 Mly, it is generally accepted that redshift-independent distance measurements, such as the Cepheid period-luminosity relation, are more accurate. According to the NED extragalactic database, median redshift-independent distances for the pair are 158 and 183 Mly respectively, indicating a separation between them of 25 Mly. In either case, as their relatively undisturbed spiral arms confirm, the galaxies appear close due to similar lines of sight, and have not yet undergone major deformations due to close physical contact.
However, both galaxies are still interacting, although not with each other. Each one displays a faint stellar stream of a dwarf falaxy which appears to be in the process of merging. And, each displays a bright blue sector in its galactic disk where its intersecting stellar stream causes a blaze of starburst activity. On the annotated image the streams are marked as A and B, while the starburst regions are marked as S1, S2, and S3. Stream A appears to follow a straight line resulting from gravitational dispersal of a dwarf galaxy as it directly approached NGC3788, causing an explosion of starburst activity (S1) as it traversed the N perimeter of the spiral disk. Meanwhile, Stream B appears as a faint oval loop formed by stellar debris from a disrupted dwarf galaxy which has merged with NGC3786, and made at least one full orbit around it. Along the S and E perimeter of the main galaxy, two luminous blue regions (S2 and S3) indicate starburst activity at the intersections between the looping stellar stream and the main galactic disk.
Physical properties of the galaxies are listed in the chart on the annotated image. Values enclosed in parentheses are based on median redshift-independent distance measurements obtained from the NED database. Depending on the distance method used, the galaxies are between 25 and 50% smaller than the Milky Way, 30 to 70% less bright, and of approximately equal size to each other. Although both galaxies have faint emission lines in the spectrum of their nuclei, and the nucleus of NGC3786 appears bright in the X-ray band, NED extragalactic database does not register an active galactic nucleus in either galaxy.
Since galactic interactions and mergers significantly influence stellar dynamics, the rates of consumption, production, and the distribution of gas and dust, synthesis of new elements (metallicity), and the nature of the galactic nucleus, galactic encounters are of great interest in the study of galactic evolution.
The attached image includes a number of remote background galaxies and two quasars listed in the chart below. The most remote of these is LAMOST J114003.83+315503.5, lying at a light travel (lookback time) distance of 8.85 Bly. The object labeled G1 is identified by Simbad as a galaxy LAMOST J113941.45+315442.2, no angular size specified, which is not listed in the NED database. The object appears starlike on high resolution HST photographs, and is most likely mis-categorized.
HST image
Image details:
-Remote Takahashi TOA 150 x 1105mm, SBIG STF-8300C, Paramount GT GEM
-OSC 36 x 300 sec, 2x drizzle, 40% linear crop
-Software: DSS, XnView, StarNet++ v2, StarTools v1.3 and 1.8, Cosmological Calculator v3
M100 (NGC 4321), NGC 4322, NGC 4328 Interacting Galaxy Group, Coma Berenices
This galaxy was discovered by Pierre Mechain in 1781, then confirmed by Messier 29 days later, and listed as entry 100 in his catalog of nebulae and star clusters. He described the object as a faint nebula without a star. It was later documented by William Herschel who noted a brighter center presumably composed of stars, and by his son John Herschel in 1833 who initially found it to be not very remarkable. Observational notes of the nebula became more interesting as telescope technologies improved over the years. By 1850, M100 appears on the list of 16 "spiral nebulae" identified with Lord Rosse's giant reflector. And by 1888, entry 4321 in Dreyer's New General Catalogue describes the nebula as a "very remarkable... 2-branched spiral... with a bright mottled nucleus." In 1990, M100 was the very first object photographed by the Hubble Space Telescope, revealing a serious spherical aberration flaw in its mirror.
In most amateur telescopes this galaxy remains a humble visual target. However, with even modest apertures, it presents a captivating photographic subject surrounded by a cluster of dwarf companions. M 100 is a nearly face-on grand design spiral galaxy with two well defined spiral arms. Infrared studies of the central region reveal a delicate bar structure, which classifies it as an intermediate spiral of the SAB morphological type. Together with all the galaxies marked in white or blue on the annotated image, M100 is a rapidly moving member of the large Virgo Galaxy Cluster. Since this group has high peculiar velocity, or rapid movement through space relative to the Milky Way, redshifts of these galaxies do not accurately reflect Hubble Flow, or the expansion of space itself, and should not be used to estimate galaxy distances. In the chart below, physical properties of the group are calculated from the redshift-independent distance measurements listed in the NASA Extragalactic Database (NED). Based on the specified median distance of 51.67 million ly, we can calculate M100's diameter of 131,000 ly, and an absolute magnitude (V) of -21.65. In terms of morphology, dimensions, and mass (approximately 400 billion stars), the galaxy is quite similar to the Milky Way. Its greater overall brightness may be due to an active galactic nucleus (AGN) of the Hii LINER type, caused by ionizing radiation emanating from the accretion disk of a central supermassive black hole (SMBH) and/or from central regions of starburst activity.
Even at low resolution, the galaxy reveals many features typical of grand design spirals. Blue floccules in the spiral arms are OB Associations - immense clusters of recently formed large, hot stars. These are typically surrounded by parent clouds of hydrogen gas, which can glow red where they re-emit energy absorbed from starlight. Yellowish color toward the middle is due to a multitude of smaller, ancient stars remaining from the early stages of galaxy formation. Dark stripes and bands weaving through the galaxy disk are large clouds of obscuring dust and gas. And, the bright region in the center is generated by a dense population of ancient stars and by emissions from a central supermassive black hole (SMBH). In some galaxies, M100 included, this nuclear region is surrounded with a ring of rapid new star formation probably driven by nuclear outflows caused by SMBH radiation pressure, SMBH winds and jets, convection plumes, and increased supernova activity.
While it displays localized areas of starburst activity around the nucleus and within spiral arms, like most other spiral galaxies in the Virgo Cluster M100 has a low neutral hydrogen content and a lower average star formation rate (SFR) than what is found in isolated, field galaxies. Hydrogen gas is lost by a process called ram-pressure stripping as a cluster galaxy with high peculiar velocity moves through a relatively dense intergalactic medium (IGM) within a cluster. For more details, see section 41 here:
www.cloudynights.com/articles/cat/articles/basic-extragal...
The attached image demonstrates a number of smaller galaxies, annotated in blue, surrounding M100. Angular proximity and similar redshift values imply - but do not prove - physical proximity and gravitational connection in 3 dimensional space. Unfortunately, redshift-independent distance estimates for five of these galaxies are not available in the literature. In order to guesstimate their physical properties, in the attached chart we make a "reasonable" assumption that their distances are approximately 52 Mly, similar to the fairly well determined M100 distance. Recent studies regarding matter distribution in our local universe reveal that most major galaxies, the Milky Way and the Andromeda included, are surrounded by substantial numbers of irregular, spheroidal, and elliptical dwarf galaxies, and that most of these are passersby rather than satellites. While complex kinematic studies are required to determine which of the galaxies in the image are gravitationally bound, streams of luminous debris between M100, NGC4322, and NGC4328 are conclusive indicators of tidal interaction. Based on their redshifts, NGC4328 had a close encounter with M100 while moving toward its foreground, and NGC4322 while moving toward its background.
The other prominent galaxy in the field is NGC4312, a nearly edge-on unbarred spiral, discovered by W. Herschel in 1787. Based on its median redshift-independent distance estimate of 35.534 Mly and angular size of 4.37 arcmin, this galaxy is about one third the diameter of the Milky Way, and about one ninth as bright. It is another high peculiar velocity member of the Virgo Galaxy Cluster which has lost much of its neutral hydrogen through ram-pressure stripping. Based on X-ray images, the galaxy is suspected of hosting an intermediate mass black hole (IMBH) with a mass between 10,000 and 300,000 solar.
The image also reveals three faint galaxies in the remote background, and a modest quasar (QSO) lying at a distance of 3.56 billion ly.
Image Details:
Remote Takahashi TOA 150 x 1105 mm
OSC 27 x 300 sec exposures, 9 discarded
2x drizzle, 55% linear crop
Software: DSS, StarNet++ v2, XnView, StarTools
The incredibly distant galaxy GS-z13-1, observed just 330 million years after the Big Bang, was initially discovered with deep imaging from the NASA/ESA/CSA James Webb Space Telescope. Now, an international team of astronomers has definitively identified powerful hydrogen emission from this galaxy at an unexpectedly early period in the Universe’s history, a probable sign that we are seeing some of the first hot stars from the dawn of the Universe.
This image shows the location of the galaxy GS-z13-1 in the GOODS-S field, as well as the galaxy itself, imaged with Webb’s Near-Infrared Camera (NIRCam) as part of the JWST Advanced Deep Extragalactic Survey (JADES) programme. These data from NIRCam allowed researchers to identify GS-z13-1 as an incredibly distant galaxy, and to put an estimate on its redshift value. Webb’s unique infrared sensitivity is necessary to observe galaxies at this extreme distance, whose light has been redshifted into infrared wavelengths during its long journey across the cosmos.
To confirm the galaxy’s redshift, the team turned to Webb’s Near-Infrared Spectrograph (NIRSpec) instrument. With new observations permitting advanced spectroscopy of the galaxy’s emitted light, the team not only confirmed GS-z13-1’s redshift of 13.0, they also revealed the strong presence of a type of ultraviolet radiation called Lyman-α emission. This is a telltale sign of the presence of newly forming stars, or a possible active galactic nucleus in the galaxy, but at a much earlier time than astronomers had thought possible. The result holds great implications for our understanding of the Universe.
[Image description: An area of deep space is covered by a scattering of galaxies in many shapes and in colours ranging from blue to whitish to orange, as well as a few nearby stars. A very small square is shown zoomed in, in a box to the left. In the centre a red dot, a faraway galaxy, is the featured galaxy JADES-GS-z13-1.]
Credits: ESA/Webb, NASA, STScI, CSA, JADES Collaboration, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Phill Cargile (CfA), J. Witstok, P. Jakobsen, A. Pagan (STScI), M. Zamani (ESA/Webb; CC BY 4.0