NGC 4038/39 – Colisão de galáxias / Collision of Galaxies

NGC 4038 e NGC 4039 sono conosciute come Antenne, o talvolta chiamate galassie “coda di topo”. Si trovano vicino al margine occidentale della costellazione del Corvo.
Questa coppia di galassie interagenti fu scoperta da William Herschel il 7 febbraio 1785 e classificata per la prima volta come una nebulosa planetaria. Suo figlio, John Herschel, li catalogò in numeri separati, h 1052 e h 1053, nel suo catalogo del 1833. Li portò nel suo catalogo generale del 1864 come GC 2670 e GC 2671; da lì, hanno trovato la loro strada nel NGC di Dreyer.

Nei piccoli telescopi, la coppia ha un’elevata luminosità superficiale e appare leggermente blu. NGC 4038 e 4039 hanno una magnitudine visiva di 10,5 e 10,3, rispettivamente, e i loro nuclei appaiono entrambi con un arco di 5,4 minuti. I nuclei delle due galassie si stanno unendo per diventare una galassia gigante; due lunghi filanti di stelle espulse, gas e polvere si estendono verso l’esterno dai loro centri, formando due lunghe code che assomigliano alle antenne di un insetto.

Le antenne si trovano a circa 63 milioni di anni luce di distanza, nel gruppo di galassie NGC 4038 nelle costellazioni di Corvo e Cratere. Le galassie più conosciute del gruppo sono NGC 4038 e 4039; ma NGC 3956, 3957, 3981, 4024, 4027, 4033 e 4050 sono stati costantemente identificati come membri del gruppo. Il gruppo può contenere tra 13 e 27 galassie. Uno studio recente ha scoperto che queste galassie interagenti potrebbero essere più vicine di quanto si pensasse, a 45 milioni di anni luce.

Name: Antennae Galaxies – NGC 4038 e NGC 4039

Type: Spiral barred galaxies (SBm) [1]

Distance: ~68.000.000 light-years [2]

Magnitude (filtro V): 10,20 [1]

Constellation: Corvus

This image shows a merging pair of galaxies. During the course of the collision, billions of stars will be formed. The brightest and most compact of these star birth regions are called super star clusters.[3]

The two spiral galaxies started to interact a few hundred million years ago, making the Antennae galaxies one of the nearest and youngest examples of a pair of colliding galaxies. The orange blobs to the left and right of image center are the two cores of the original galaxies and consist mainly of old stars criss-crossed by filaments of dust, which appears brown in the image. The two galaxies are dotted with brilliant blue star-forming regions surrounded by glowing hydrogen gas, appearing in the image in pink and red.[3]

By age dating the clusters in the image, astronomers find that only about 10 percent of the newly formed super star clusters in the Antennae will survive beyond the first 10 million years. The vast majority of the super star clusters formed during this interaction will disperse, with the individual stars becoming part of the smooth background of the galaxy. It is however believed that about a hundred of the most massive clusters will survive to form regular globular clusters, similar to the globular clusters found in our own Milky Way galaxy. The Antennae galaxies take their name from the long antenna-like “arms” extending far out from the nuclei of the two galaxies, best seen by ground-based telescopes. These “tidal tails” were formed during the initial encounter of the galaxies some 200 to 300 million years ago. They give us a preview of what may happen when our Milky Way galaxy collides with the neighboring Andromeda galaxy in several billion years.[3]

Source:

[1] – HyperLeda – Database for physics of galaxies – leda.univ-lyon1.fr/ledacat.cgi?o=ngc6744

[2] – The Tip of the Red Giant Branch Distances to Type Ia Supernova Host Galaxies. III. NGC 4038/39 and NGC 5584, Jang, In Sung; Lee, Myung Gyoon – The Astrophysical Journal

[3] – Nasa – www.nasa.gov/multimedia/imagegallery/image_feature_1086.html

This image was captured at days 7th, 8th and 20th June 2019 in rural zone of Munhoz – Minas Gerais – Brazil. Bortle Scale 4.

Technical data:

Gain 139, offset 10, Bin 1×1, sensor’s temperature -20°C, total exposition of de 7h01m (129 subs), darks (40), flats (180) and darks flats (80) applied.

Filters:

H-Alpha 17 x 300s

Luminance (IR/UV Cut) 60 x 180s

Red 21 x 180s

Green 17 x 180s

Blue 14 x 180s

Equipments:

– Equatorial Mount Orion Atlas EQ-G

– GSO Ritchey-Chretien Telescope 8″ F8 Carbon Fiber

– ZWO ASI1600MM Cooled

– Focal reducer Astro-Physics 67 CCDT

– Guided with ZWO ASI120MM using OAG

– ZWO Filter Wheel (8 x 1.25″)

– Filter Optolong 1.25″ H-Alpha 7nm

– Filter Optolong 1.25″ Luminance

– Filter Optolong 1,25″ Red

– Filter Optolong 1,25″ Green

– Filter Optolong 1,25″ Blue

Softwares

– Capture: APT – Astro Photography Tool 3.50

– Processing: PixInsight 1.8 and Adobe Photoshop CS5

– Guiding: PHD2

– Control: EQMOD and SkyTechX

Autore: Wellerson Lopes (sito)