DGSAT I

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DGSAT I
Ultra diffuse galaxy DGSAT I.jpg
Observation data
Right ascension 01h 17m 35.59s [1]
Declination 33° 31 42 [1]
Redshift 78 Mpc [1]
Heliocentric radial velocity 5450 ± 40 km/s [1]
Distance 254.4 ± 3.3  Mly (78 ± 1  Mpc) [1]
Apparent magnitude  (V)18.18 ± 0.04 [1]
Absolute magnitude  (V)-16.3 ± 0.1 mag [1]
Characteristics
Mass 4.0 × 10×108 [1]   M
Mass/Light ratio 1.1 [1]   M/L
DGSAT I. Ultra diffuse galaxies are hard to spot due to low luminosity and wispy appearance. Ultra diffuse galaxy DGSAT I Indicated.png
DGSAT I. Ultra diffuse galaxies are hard to spot due to low luminosity and wispy appearance.

DGSAT I is a quenched, ultra diffuse galaxy (UDG) located on the outskirts of the Pisces-Perseus Supercluster, identified in 2016 during a visual inspection of a full color image of the Andromeda II dwarf galaxy. [1] DGSAT I resides in a low-density environment compared to the densities where UDGs are typically found. [2] Its chemical makeup have led astronomers to propose it was formed during the dawn of the universe when galaxies emerged in a different environment than today. [3] [4] [5] [6]

Contents

Discovery and identification

DGSAT I was first identified by the DGSAT project in 2016. [7] The DGSAT (Dwarf Galaxy Survey with Amateur Telescopes) uses the potential of privately owned small-sized telescopes to probe low surface brightness (LSB) features around large galaxies and aims to increase the sample size of the dwarf satellite galaxies in the Local Volume. [7] [8]

At first astronomers thought DGSAT I to be an isolated dwarf galaxy beyond the Local Group due to its structural properties and absence of emission lines. A spectroscopic observation later revealed DGSAT I to be a background system and likely associated with an outer filament of the Pisces-Perseus super-cluster. [7]

Chemical composition

The chemical composition of a galaxy provides record of the ambient conditions during its formation. The mass ratios of alpha-elements such as magnesium to iron ([Mg/Fe]) trace time-scales for star formation, as these elements are produced by stars according to different lifetimes. [2] Younger galaxies tend to have more heavy elements in its chemical makeup compared to ancient galaxies formed during an early age of the universe. [3]

DGSAT I's integral field spectroscopy data shows a remarkably low iron content, suggesting an early galaxy formed from a nearly pristine gas cloud, unpolluted by the supernova death of previous stars, however its magnesium levels are consistent with what astronomers expect to find in younger galaxies. [3] This apparent chemical makeup discrepancy and DGSAT I's isolation from galaxy clusters are helping astronomers to develop new theories concerning the birth and formation of UDGs. [3]

UDGs are hard to observe due to their extremely low luminosity but there are studies being conducted using the Keck Cosmic Web Imager in an attempt to shed light on the precise relation between DGSAT I's metallicity and its possibly exotic origin. [2] A paper published in 2022 proposed DGSAT I to be a “failed galaxy” that formed relatively few stars in proportion to its halo mass, and could be related to cluster UDGs whose size and quiescence pre-date their infall [9] (i.e. when molecular transition shows evidence of gas flowing into the core of the star).

See also

Related Research Articles

<span class="mw-page-title-main">Local Group</span> Group of galaxies that includes the Milky Way

The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10^6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.

The following is a timeline of galaxies, clusters of galaxies, and large-scale structure of the universe.

<span class="mw-page-title-main">NGC 404</span> Galaxy in the constellation Andromeda

NGC 404 is a field galaxy located about 10 million light years away in the constellation Andromeda. It was discovered by William Herschel in 1784, and is visible through small telescopes. NGC 404 lies just beyond the Local Group and does not appear gravitationally bound to it. It is located within 7 arc-minutes of second magnitude star Mirach, making it a difficult target to observe or photograph and granting it the nickname "Mirach's Ghost".

<span class="mw-page-title-main">Dwarf galaxy</span> Small galaxy composed of up to several billion stars

A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

<span class="mw-page-title-main">Sculptor Galaxy</span> Intermediate spiral galaxy in the constellation Sculptor

The Sculptor Galaxy is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.

A dark galaxy is a hypothesized galaxy with no stars. They received their name because they have no visible stars but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds. The best candidate dark galaxies to date include HI1225+01, AGC229385, and numerous gas clouds detected in studies of quasars.

<span class="mw-page-title-main">NGC 5170</span> Edge-on spiral galaxy in the constellation Virgo

NGC 5170 is a large, nearby, edge-on spiral galaxy in the equatorial constellation of Virgo. It was discovered on February 7, 1785 by William Herschel. This galaxy is located at a distance of 83.5 million light years and is receding at a heliocentric radial velocity of 1,502 km/s. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster.

<span class="mw-page-title-main">NGC 4449</span> Galaxy in the constellation Canes Venatici

NGC 4449, also known as Caldwell 21, is an irregular Magellanic type galaxy in the constellation Canes Venatici, being located about 13 million light-years away. It is part of the M94 Group or Canes Venatici I Group that is relatively close to the Local Group hosting our Milky Way galaxy.

<span class="mw-page-title-main">Pavo–Indus Supercluster</span> Neighboring supercluster in the constellations Pavo, Indus and Telescopium

The Pavo–Indus Supercluster is a neighboring supercluster located about 60–70 Mpc (196–228 Mly) away in the constellations of Pavo, Indus, and Telescopium. The supercluster contains three main clusters, Abell 3656, Abell 3698, and Abell 3742.

<span class="mw-page-title-main">Galaxy filament</span> Largest structures in the universe, made of galaxies

In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50/h to 80/h Megaparsecs —with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length—and form the boundaries between voids. Due to the accelerating expansion of the universe, the individual clusters of gravitationally bound galaxies that make up galaxy filaments are moving away from each other at an accelerated rate; in the far future they will dissolve.

<span class="mw-page-title-main">NGC 3669</span> Galaxy in the constellation Ursa Major

NGC 3669 is a barred spiral galaxy in the constellation Ursa Major. It was discovered by William Herschel on March 18, 1790. The galaxy is seen edge-on and appears to be slightly warped. It has a small bulge.

<span class="mw-page-title-main">R. Jay GaBany</span> American astronomer and astrophotographer

Robert Jay GaBany is an American amateur astronomer and astrophotographer who is also known for his work with an international team of astrophysicists led by Dr. David Martínez-Delgado. GaBany helped pioneer the use of modest size telescopes and off the shelf CCD-cameras to produce long exposure images that revealed ancient galactic merger remnants in the form of star streams surrounding nearby galaxies that were previously undetected or suspected.

<span class="mw-page-title-main">Ultra diffuse galaxy</span> Extremely low luminosity galaxy

An ultra diffuse galaxy (UDG), or Dark galaxy, is an extremely low luminosity galaxy, the first example of which was discovered in the nearby Virgo Cluster by Allan Sandage and Bruno Binggeli in 1984. These galaxies have been studied for many years prior to their renaming in 2015. Their lack of luminosity is due to the lack of star-forming gas, which results in these galaxies being reservoirs of very old stellar populations.

<span class="mw-page-title-main">Dragonfly 44</span> Galaxy in constellation Coma Berenices

Dragonfly 44 is an ultra diffuse galaxy in the Coma Cluster. This galaxy is well-known because observations of the velocity dispersion in 2016 suggested a mass of about one trillion solar masses, about the same as the Milky Way. This mass was consistent with a count of about 90 and 70 globular clusters observed around Dragonfly 44 in two different studies.

<span class="mw-page-title-main">NGC 1052-DF2</span> Ultra diffuse galaxy in the constellation Cetus

NGC 1052-DF2 is an ultra diffuse galaxy (UDG) in the constellation Cetus, which was identified in a wide-field imaging survey of the NGC 1052 group by the Dragonfly Telephoto Array. It has been proposed that the galaxy contains little or no dark matter, the first such discovery. On 20 March 2019, a follow-up study announcing the discovery of a second UDG lacking dark matter, NGC 1052-DF4, was published.

<span class="mw-page-title-main">Donatiello I</span> Dwarf spheroidal galaxy located in the constellation Andromeda

Donatiello I, also known as Mirach's Goblin, is a dwarf spheroidal galaxy in the constellation Andromeda, located between 8.1 and 11.4 million light-years from Earth. It is a possible satellite galaxy of the dwarf lenticular galaxy NGC 404, "Mirach's Ghost", which is situated 60 arcminutes away. It is otherwise one of the most isolated dwarf spheroidal galaxies known, being separated from NGC 404 by around 211,000 light-years. The galaxy is named after its discoverer, amateur astronomer and astrophotographer Giuseppe Donatiello, who sighted the galaxy in a 2016 review of his archival long exposures from 2010 and 2013. Follow-up observations with the Roque de los Muchachos Observatory led to a scientific paper on its discovery being published in December 2018.

<span class="mw-page-title-main">NGC 765</span> Galaxy in the constellation Aries

NGC 765 is an intermediate spiral galaxy located in the constellation Aries. It is located at a distance of circa 220 million light years from Earth, which, given its apparent dimensions, means that NGC 765 is about 195,000 light years across. It was discovered by Albert Marth on October 8, 1864. The galaxy has an extensive hydrogen (HI) disk with low surface brightness, whose diameter is estimated to be 240 kpc.

References

  1. 1 2 3 4 5 6 7 8 9 10 Martínez-Delgado; Läsker; Sharina; Toloba; Fliri; Beaton; Valls-Gabaud; Karachentsev; Chonis; Grebel; Forbes; Romanowsky; Gallego-Laborda; Teuwen; Ómez-Flechoso; Wang; Guhathakurta; Kaisin; Ho (2016). "Discovery of an ultra diffuse galaxy in the Pisces-Perseus Supercluster". The Astronomical Journal. 151 (4): 96. arXiv: 1601.06960 . Bibcode:2016AJ....151...96M. doi: 10.3847/0004-6256/151/4/96 .
  2. 1 2 3 Martín-Navarro; Romanowsky; Brodie; Ferré-Mateu; Alabi; Forbes; Sharina; Villaume; Pandya; Martínez-Delgado (2019). "Extreme chemical abundance ratio suggesting an exotic origin for an ultradiffuse galaxy". Monthly Notices of the Royal Astronomical Society. 484 (3): 3425–3433. arXiv: 1901.08068 . doi: 10.1093/mnras/stz252 .
  3. 1 2 3 4 "Anemic Galaxy Reveals Deficiencies in Ultra-Diffuse Galaxy Formation Theory – W. M. Keck Observatory" . Retrieved 2023-10-31.
  4. Ciaccia, Chris (2019-03-08). "'Living fossil' from the dawn of the universe discovered in deep space". Fox News. Retrieved 2023-11-11.
  5. Parnell, Brid-Aine. "New Ghost Galaxy Is A Time Capsule From The Dawn Of The Universe". Forbes. Retrieved 2023-11-11.
  6. "Starry tail tells the tale of dwarf galaxy evolution". ScienceDaily. Retrieved 2023-11-11.
  7. 1 2 3 "Ultra-deep imaging with amateur telescopes - David Martínez-Delgado". ned.ipac.caltech.edu. Retrieved 2023-11-04.
  8. B. Javanmardi; D. Martinez-Delgado; P. Kroupa; C. Henkel; K. Crawford; K. Teuwen; R. J. Gabany; M. Hanson; T. S. Chonis; F. Neyer (2016). "DGSAT: Dwarf Galaxy Survey with Amateur Telescopes". Astronomy & Astrophysics. 588: A89. arXiv: 1511.04446 . doi: 10.1051/0004-6361/201527745 . S2CID   119189074.
  9. Janssens, Steven R.; Romanowsky, Aaron J.; Abraham, Roberto; Brodie, Jean P.; Couch, Warrick J.; Forbes, Duncan A.; Laine, Seppo; Martínez-Delgado, David; van Dokkum, Pieter G. (2022-10-07). "The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I". Monthly Notices of the Royal Astronomical Society. 517 (1): 858–871. arXiv: 2209.09910 . doi:10.1093/mnras/stac2717. ISSN   0035-8711.