NGC 7722
| Galaxie NGC 7722 | |
|---|---|
.jpg) (c) ESA/Hubble, CC BY 4.0 | |
| Aufnahme durch das Hubble-Weltraumteleskop | |
| AladinLite | |
| Sternbild | Pegasus |
| Position Äquinoktium: J2000.0, Epoche: J2000.0 | |
| Rektaszension | 23h 38m 41,2s [1] |
| Deklination | +15° 57′ 17″ [1] |
| Erscheinungsbild | |
| Morphologischer Typ | S0/a / LINER[1] |
| Helligkeit (visuell) | 12,4 mag[2] |
| Helligkeit (B-Band) | 13,3 mag[2] |
| Winkelausdehnung | 1,7' × 1,4'[2] |
| Positionswinkel | 150°[2] |
| Flächenhelligkeit | 13,2 mag/arcmin²[2] |
| Physikalische Daten | |
| Zugehörigkeit | NGC 7711-Gruppe LGG 477[1][3] |
| Rotverschiebung | 0.013429 ± 0.000017[1] |
| Radialgeschwindigkeit | (4026 ± 5) km/s[1] |
| Hubbledistanz H0 = 73 km/(s • Mpc) | (187 ± 13)e6 Lj (57,4 ± 4,0) Mpc [1] |
| Geschichte | |
| Entdeckung | Heinrich d’Arrest |
| Entdeckungsdatum | 12. August 1864 |
| Katalogbezeichnungen | |
| NGC 7722 • UGC 12718 • PGC 71993 • CGCG 455-035 • MCG +03-60-017 • IRAS 23361+1540 • 2MASX J23384119+1557174 • NVSS J233841+155721 • LDCE 1581 NED009 | |
NGC 7722 ist eine linsenförmige Galaxie mit aktivem Galaxienkern vom Hubble-Typ S0/a im Sternbild Pegasus am Nordsternhimmel. Sie ist schätzungsweise 187 Millionen Lichtjahre von der Milchstraße entfernt und hat einen Durchmesser von etwa 90.000 Lichtjahren.
Viele der bekannten linsenförmigen Galaxien weisen Merkmale sowohl von Spiral- als auch von elliptischen Galaxien auf. In diesem Fall fehlen der Galaxie die ausgeprägten Arme einer Spiralgalaxie, während sie einen ausgedehnten, leuchtenden Halo und einen hellen Wulst im Zentrum aufweist, ähnlich wie eine elliptische Galaxie. Im Gegensatz zu elliptischen Galaxien hat sie eine sichtbare Scheibe, da konzentrische Ringe um ihren hellen Kern wirbeln. Ihr auffälligstes Merkmal sind jedoch zweifellos die langen Streifen aus dunkelrotem Staub, die sich um die äußere Scheibe und den Halo winden.
Im selben Himmelsareal befinden sich u. a. die Galaxien NGC 7703 und NGC 7711.
Das Objekt wurde am 12. August 1864 von Heinrich Louis d’Arrest entdeckt.[4]
Weblinks
- SIMBAD Astronomical Database
- NASA/ESA Hubble Space Telescope: NGC 7722 in dark surroundings (wide crop) engl.
Einzelnachweise
Auf dieser Seite verwendete Medien
Dark rings and new light (potm2601a).jpg
(c) ESA/Hubble, CC BY 4.0
For this Picture of the Month from the NASA/ESA Hubble Space Telescope, we have a sight of an uncommon galaxy with a striking appearance. This is NGC 7722, a lenticular galaxy located about 187 million light-years away in the constellation Pegasus.A “lenticular”, meaning “lens-shaped”, galaxy is a type that sits in between the more familiar spiral galaxies and elliptical galaxies. It is also less common than these — partly because when a galaxy has an ambiguous appearance, it can be hard to determine if it is actually a spiral, actually an elliptical galaxy, or something in between. Many of the known lenticular galaxies sport features of both spiral and elliptical galaxies. In this case, NGC 7722 lacks the defined arms of a spiral galaxy, while it has an extended, glowing halo and a bright bulge in the centre similar to an elliptical galaxy. Unlike elliptical galaxies, it has a visible disc — concentric rings swirl around its bright nucleus. Its most prominent feature, however, is undoubtedly the long lanes of dark red dust coiling around the outer disc and halo.This new Hubble image, the sharpest yet taken of NGC 7722, brings the impressive dust lanes into sharp focus. Bands of dust like this are not uncommon in lenticular galaxies, and they stand out against the broad, smooth halo of light that typically surrounds lenticular galaxies. The distinctive dust lanes of NGC 7722 are thought to result from a merger with another galaxy in the past, similar to other lenticular galaxies. It is not yet fully understood how lenticular galaxies form, but mergers and other gravitational interactions are thought to play an important part, reshaping galaxies and exhausting their supplies of gas while bringing new dust.While it doesn’t host as many new, young stars as a spiral galaxy, there’s still activity in NGC 7722: in 2020 it was host to the explosion of a star that could be detected from Earth. SN 2020SSF was a Type Ia supernova, an event which occurs when a white dwarf star in a binary system siphons enough mass away from its companion star that it grows unstable and explodes. These explosions output a remarkably consistent level of light: by measuring how bright they appear from Earth and comparing against how bright they really are, it’s possible to tell how far away they must be. Type Ia supernovae are one of the best ways to measure distances to galaxies, so understanding exactly how they work is of great importance to astronomers.Taken with Hubble’s Wide Field Camera 3, this Hubble image was obtained as part of an observing programme (#16691, PI: R. J. Foley) that followed up on recent supernovae. SN 2020SSF is not visible in this image, as it was actually taken two years later, when the supernova had long faded. This was on purpose: the aim of the observations was to witness the aftereffects of the supernova and examine its surroundings, which can only be done once the intense light of the explosion is gone. With Hubble’s clear vision, astronomers can search for radioactive material created by the supernova, catalogue its neighbours to see how old the star likely was, and look for the companion star it left behind — all from almost 200 million light-years away.[Image Description: A disc-shaped galaxy. It glows brightly at the centre and shines a faint white light all around it. The disc is made up of tightly-packed rings of dust, some darker and some lighter. Wide, long lanes of dark reddish dust cross the galaxy in front of its edge, blocking out some of its light; the long strands twist and break apart at each side. A couple of nearby stars and distant galaxies are also visible on the black background.]
(c) ESA/Hubble, CC BY 4.0
For this Picture of the Month from the NASA/ESA Hubble Space Telescope, we have a sight of an uncommon galaxy with a striking appearance. This is NGC 7722, a lenticular galaxy located about 187 million light-years away in the constellation Pegasus.A “lenticular”, meaning “lens-shaped”, galaxy is a type that sits in between the more familiar spiral galaxies and elliptical galaxies. It is also less common than these — partly because when a galaxy has an ambiguous appearance, it can be hard to determine if it is actually a spiral, actually an elliptical galaxy, or something in between. Many of the known lenticular galaxies sport features of both spiral and elliptical galaxies. In this case, NGC 7722 lacks the defined arms of a spiral galaxy, while it has an extended, glowing halo and a bright bulge in the centre similar to an elliptical galaxy. Unlike elliptical galaxies, it has a visible disc — concentric rings swirl around its bright nucleus. Its most prominent feature, however, is undoubtedly the long lanes of dark red dust coiling around the outer disc and halo.This new Hubble image, the sharpest yet taken of NGC 7722, brings the impressive dust lanes into sharp focus. Bands of dust like this are not uncommon in lenticular galaxies, and they stand out against the broad, smooth halo of light that typically surrounds lenticular galaxies. The distinctive dust lanes of NGC 7722 are thought to result from a merger with another galaxy in the past, similar to other lenticular galaxies. It is not yet fully understood how lenticular galaxies form, but mergers and other gravitational interactions are thought to play an important part, reshaping galaxies and exhausting their supplies of gas while bringing new dust.While it doesn’t host as many new, young stars as a spiral galaxy, there’s still activity in NGC 7722: in 2020 it was host to the explosion of a star that could be detected from Earth. SN 2020SSF was a Type Ia supernova, an event which occurs when a white dwarf star in a binary system siphons enough mass away from its companion star that it grows unstable and explodes. These explosions output a remarkably consistent level of light: by measuring how bright they appear from Earth and comparing against how bright they really are, it’s possible to tell how far away they must be. Type Ia supernovae are one of the best ways to measure distances to galaxies, so understanding exactly how they work is of great importance to astronomers.Taken with Hubble’s Wide Field Camera 3, this Hubble image was obtained as part of an observing programme (#16691, PI: R. J. Foley) that followed up on recent supernovae. SN 2020SSF is not visible in this image, as it was actually taken two years later, when the supernova had long faded. This was on purpose: the aim of the observations was to witness the aftereffects of the supernova and examine its surroundings, which can only be done once the intense light of the explosion is gone. With Hubble’s clear vision, astronomers can search for radioactive material created by the supernova, catalogue its neighbours to see how old the star likely was, and look for the companion star it left behind — all from almost 200 million light-years away.[Image Description: A disc-shaped galaxy. It glows brightly at the centre and shines a faint white light all around it. The disc is made up of tightly-packed rings of dust, some darker and some lighter. Wide, long lanes of dark reddish dust cross the galaxy in front of its edge, blocking out some of its light; the long strands twist and break apart at each side. A couple of nearby stars and distant galaxies are also visible on the black background.]