Wellen und Schalen
Im Vergleich zu ihren komplizierteren Verwandten, den Spiralgalaxien, ähneln elliptische Galaxien vom Anblick her fluffigen Wolken. Diese Galaxien haben sanfte, undefinierte Ränder und helle Zentralbereiche, die von einem diffusen Leuchten umgeben sind. Allerdings kann das Aussehen trügen: Mindestens 10% der elliptischen Galaxien reichen viel weiter in den Kosmos hinaus, als man erwarten würde, und haben eine Reihe von weitaus feineren Strukturen, als man zunächst denkt - wie zum Beispiel Bögen und Schalen.
Unten links im Bild sehen wir die etwa 100 Millionen Lichtjahre entfernte Galaxie NGC 474. Sie befindet sich im Sternbild Fische und ist ein erstaunliches Beispiel einer elliptischen Schalengalaxie: riesige, zarte Gezeitenschweife schlängeln sich um den Hauptkörper der Galaxie, während ihre innere Struktur aus einer Reihe von verschachtelten, konzentrischen Ringen besteht. Tatsächlich kann es sein, dass die Galaxie in ihrer vollen Ausdehnung nicht einmal in das Bildfeld passt. Die rankenartigen äußeren Regionen von NGC 474 wogen und wispern wie Rauch und erstrecken sich über große Entfernungen vom inneren Bereich der Galaxie nach außen.
Die Astronomen sind sich nicht sicher, warum einige Galaxien diese Art von Aussehen und Struktur annehmen, aber sie glauben, dass es sich um die Schwerkraft dahinter steckt - dadurch dass nahe Galaxien gravitativ miteinander wechselwirken. Es ist möglich, dass die Spiralgalaxie unten rechts, NGC 470, seit Milliarden von Jahren an ihrem größeren Freund zerrt und Dichtewellen ihre Struktur verändern.
Diese Galaxie wurde im Rahmen des Cosmic-Gems-Programms der ESO beobachtet, einer Initiative zur Erstellung von Bildern interessanter, faszinierender oder visuell attraktiver Objekte mit den ESO-Teleskopen zu Bildungs- und Öffentlichkeitsarbeitszwecken. Das Programm nutzt Beobachtungszeit der Teleskope, die nicht für wissenschaftliche Beobachtungen geeignet ist. Alle gesammelten Daten können auch für wissenschaftliche Zwecke genutzt werden und werden den Astronomen über das Wissenschaftsarchiv der ESO zur Verfügung gestellt.
Bildnachweis:ESO
Über das Bild
| ID: | potw2001a |
| Sprache: | de-be |
| Typ: | Beobachtung |
| Veröffentlichungsdatum: | 6. Januar 2020 06:00 |
| Größe: | 1726 x 1744 px |
Über das Objekt
| Name: | NGC 470, NGC 474 |
| Typ: | Local Universe : Galaxy : Type : Spiral |
| Entfernung: | 100 Million Lichtjahre |
| Constellation: | Pisces |
Bildschirm-Hintergrundbilder
Koordinaten
| Position (RA): | 1 19 55.68 |
| Position (Dec): | 3° 24' 34.10" |
| Field of view: | 7.32 x 7.24 arcminutes |
| Orientierung: | Die Nordrichtung liegt 45.1° links zur Vertikale |
Farben & Filter
| Spektralbereich | Wellenlänge | Teleskop |
|---|---|---|
| Optisch b | 440 nm | Very Large Telescope FORS2 |
| Optisch v | 557 nm | Very Large Telescope FORS2 |
| Optisch R | 655 nm | Very Large Telescope FORS2 |
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