The Trifid Nebula has been imaged like never before, revealing stars never before seen by astronomers.
The Vista telescope in Chile, managed by the European Southern Observatory (ESO) was utilized to take the new image. The new photograph reveals two previously-unknown Cepheid variable stars, placed far beyond the nebula. These stellar objects, much brighter than our own Sun, brighten and fade over a fixed period of time. The cycle for both of these stars lasts around 11 days. The pair of stellar bodies also exhibits similar colors, and brightness, as seen from Earth, suggesting both stars are roughly the same age. These are the first Cepheid variable stars ever discovered in the central plane of our galaxy, on the other side of the central core of the Milky Way.
"The familiar pictures of the Trifid show it in visible light, where it glows brightly in both the pink emission from ionised hydrogen and the blue haze of scattered light from hot young stars... But the view in the VISTA infrared picture is very different... The dust clouds are far less prominent and the bright glow from the hydrogen clouds is barely visible at all," ESO officials reported on their Web page.
Dust clouds near the center of our galaxy prevent astronomers from viewing the core of the Milky Way in visible light. Astronomers studying the Trifid Nebula in this latest study used infrared light to image objects inside and beyond the object.
Astronomers believe the newly-recognized stars lie around 37,000 light years from Earth, roughly 10,000 light years past the central core of the galaxy. The Trifid Nebula itself sits just 5,200 light years away from our home planet. Because the two Cepheid variable stars are so similar, astronomers believe the objects may be the two brightest members of an unknown cluster of stars. Attempted detection of other members of the group was not successful.
The Vista Variables in the Via Lactea survey (VVV) being conducted at the observatory is re-examining objects in the night sky, in order to find objects with varying brightness. The study is focusing on astronomical bodies in the general direction of the center of the Milky Way. This program, which examines bodies in five bands of infrared light, started in February 2010 and is scheduled for completion later in 2015.
The Trifid Nebula, also known as M20, is a popular target for amateur astronomers.
Discovery of the Cepheid variable stars beyond the Trifid Nebula was detailed in the journal Astrophysical Journal Letters.