The Young Astronomers
Currently viewing the tag: "ESO"
NASA’s Chandra X-ray Observatory (along with optical data provided by the ESO and infra-red data supplied by the Spitzer space telescope) has produced a truly amazing image of the star cluster NGC 1929 located within the nebula N44.
N44 and NGC 1929 Credit:X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m
The nebula and its star cluster are located in the Milky Way’s largest satellite galaxy – the Large Magellanic Cloud (LMC) – at a distance of 160,000 light years from Earth - 940.6 quadrillion miles.
The star cluster is composed of primarily newborn stars that have only recently been forged from the surrounding material.A great number of these are many times the mass of the sun and produce a precipitous amount of hard radiation and vicious solar winds, before burning out in (on the time scales of the universe) sort order as supernovae generating incredible outpourings of energy.
These shockwaves along with the continual bombardment from radiation and particle stream gouges out massive ‘bubbles’ in the surrounding nebula. The x-ray data provided by Chandra (shown in blue) shows the regions of the nebula that are at the highest temperatures – the areas under the heaviest onslaught of radiation or reeling from one or more shockwaves . The cooler gas and dust as detected by Spitzer is displayed in red with the yellow regions show where the radiation is actually causing the surrounding material to glow in the visible range (this data was collected by the ESO’s Max-Planck telescope).
Astronomers have been having a problem with N44 and other similar ‘superbubbles’ in the LMC for sometime now – they are producing too many x-rays.
Before anyone panics, this is not a medical problem (we aren’t all going to suffer radiation poisoning thanks to a few over-active nebulae in another galaxy), it only refers to the measurements pointing to such nebulae producing more x-rays than could be explained using current knowledge – our knowledge of such objects must be incomplete.
A previous study had suggested that the shockwaves of supernovae impacting the bubble’s walls along with the evaporation of hot material from the sides of the bubble could perhaps explain this anomaly. This set of observations at least doesn’t find any supporting evidence for these ideas though it has been the first time that the observations have been sensitive to distinguish between these and other possibilities so progress is being made.
You can read more here
The ESO has recently released this truly stunning image of the nebula M78
Messier 78 Credit: ESO/APEX (MPIfR/ESO/OSO)/T. Stanke et al./Igor Chekalin/Digitized Sky Survey 2
The nebula sits just north of the stars in Orion’s belt at roughly 1600 light years from Earth.
In visible wavelengths (those displayed in the image as blues, whites and browns) M78 is a reflection nebula – that is one that reflects the light of nearby stars rather than producing its own – however the new data from the Atacama Pathfinder Experiment (APEX) telescope which detects sub-millimetre infra-red light reveals that the nebula is actually gently glowing from within – displayed as orange in the image.
These emissions correspond to cool dusty regions within the murky clouds of the nebula. Some of these regions are colder than -250oC! If viewed in visible light the cool dust blocks any attempts to peer within though with the sub-millimetre we can gaze through the clouds and learn what lies within.
The softly glowing clumps are the birthplaces of stars, indeed the lower bright region contains low mass stars (similar to or smaller than our own Sun) at various stages of formation and the upper bright region (actually a distinct nebula in its own right – NGC 2071) contains more massive stars with at least one weighing in at more than five times the mass of Sol.
You can read more about this nebula and the recent observations at the ESO article here
In celebration of the Hubble Space Telescope’s 22nd anniversary the ESA has released this truly stunning image of the star forming region 30 Doradus.
30 Doradus Credit: NASA, ESA, ESO, D. Lennon and E. Sabbi (ESA/STScI), J. Anderson, S. E. de Mink, R. van der Marel, T. Sohn, and N. Walborn (STScI), N. Bastian (Excellence Cluster, Munich), L. Bedin (INAF, Padua), E. Bressert (ESO), P. Crowther (Sheffield), A. de Koter (Amsterdam), C. Evans (UKATC/STFC, Edinburgh), A. Herrero (IAC, Tenerife), N. Langer (AifA, Bonn), I. Platais (JHU) and H. Sana (Amsterdam)
30 Doradus is better known as the Tarantula nebula and is located 170,000 light years away within the Milky Way’s largest satellite galaxy the Large Magellanic Cloud (LMC).
The image shows a region of space approximately 650 light years across with several million stars present within. Combined, the sum total of the stars’ masses shown in this image would be well over a million times the mass of our own Sun.
The stars are grouped into smaller clusters ranging in age from about 2 million – 25 million years old, whilst this may sound ancient in human terms as far as the universe is concerned even the oldest star in the region is a newcommer.
The brightest cluster is NGC 2070 being one of the youngest (between 2 and 3 million years old) and most actively starforming regions with the larger structure Astronomers find it an attractive region to study. Recently in fact, it was revealed that at the heart of the cluster (which contains upwards of half a million stars) there is a dense clump of stars designated RMC 136 where the largest stars yet discovered reside. Indeed several of these monsters are more than 100 times the mass of our own sun, truly cosmic giants.
The fierce output of the regions hot stars sculpts the regions gas and just into the fantastic arcs and bubbles we can see in the image. The fierce radiation bombardment of radiation is also exciting the gas and dust molecules of the nebula making them glow in their own right and classing the region as an emission nebula.
The image is composed of data from both Hubble and the ESO’s MPG/ESO 2.2-metre telescope and represents the one of the largest such mosaics in existence today. The data was captured by both telescopes during an observing run in October 2011.
You can read more here.
Back in late September 2010, Astronomers made an important discovery that may eventually change the way we view our place in the cosmos.
The story begins with the all together average star Gliese 581 The star is a spectral class M3 main sequence dwarf, not dissimilar to the image on the left.
An artist's impression of an M class dwarf Credit: NASA/Walt Feimer
At roughly 31% the mass of the sun but only 1.3% its luminosity (that is taking all wavelengths into account not just visual i.e. its Bolometric luminosity).
The star is classified as a variable star due to fluctuations in its brightness over time.
To be more specific it is a BY Draconis variable star as the variability (if confirmed as it currently falls close to the accepted margin for false detection) is expected to be caused by the presence of starspots (the general name for a sunspot that occurs on a star other than the sun) combined with the star’s rotation.
Whilst the star is itself an interesting object, it is what is orbiting it that has caused the media interest beginning in spring 2007.The star has been a target in the search for Exoplanets for some time, the excitement spread when its second planet – Gliese 581c – was revealed to sit just at the inner edge of the systems ‘habitable’ zone.
The term ‘habitable zone’ for a start deeply aggravates me as it means only that the area is neither too hot or too cold, I would prefer it to be known as the ‘temperate’ zone but perhaps that is just me (18 going on a grumpy 60 year old).
Gliese 581 Credit: Digital Sky Survey / ESO
The word habitable implies that the world is suitable for life in every way not just one. Professional astronomers refer to this zone as the ‘Goldilocks zone’ instead as this only refers to the distance from a star that liquid water could theoretically exist on the surface of a terrestrial (rocky) world. Without leading to the assumption that as planet x is y km from its star then it must have life. All this position means is that planet x is in the most likely area of its system for a planet to have liquid water.
The attention soon waned as it became clear that the planet is likely to have a runaway greenhouse effect creating a Venusian world far too hot for life.
The media hype began again with the discovery of the Gliese 581d which sits at the very edge or just outside the Goldilocks zone and so can be expected to be similar to Mars. Then interest peaked again with the discovery of Gliese 581 e which despite sitting very close to the star was the exoplanet with the closest mass to that of the Earth yet discovered with a minimum mass of 1.94 Earth masses.
The current media extravaganza is centred on Gliese 581 g a planet that sits well within the Goldilocks zone, and within the acceptable mass limits for a stable terrestrial planet meaning that it COULD Potentially be suitable for life. However as I have mentioned the issue is far more complex than just having a planet at roughly the right distance from a star.
The Gliese 581 System. Showing each planet's orbital distance in relation to the projected location of the habitable zone and relative to our own Solar System. Credit: ESO derivative work: Henrykus
Yes could be a life bearing world but there is no proof either way quite yet.
Well as the planet is sitting just 20.3 light years away from us, if it indeed harbours life it would go some way to showing just how common life is likely to be within the universe.
However a spanner may have been thrown into the works.
All exoplanet detections must be confirmed, i.e. by the detection of the planet in more than one dataset. So far Gliese 581 g (and Gliese 581 f, announced at the same time though more mundane as it falls well outside the habitable zone and is expected to be similar to Neptune or a super terrestrial planet) has only been detected in one set of measurements; a set of combined data from HIRES spectrometer on the Keck telescope in Hawaii and the HARPS instrument on the ESO’s La Silla Observatory in Chile.Later measurements taken by HARPS failed to detect the planet, so it may not exist at all.
Though as Martin Rees once said, “Lack of evidence is not evidence for absence.” Who knows the planet may yet be confirmed in later measurements though that’s not quite the end of our story.
During the buzz of attention surrounding the discovery of Gliese 581 c, a radio transmission was sent to the system containing messages selected by users of the social networking site Bebo.The transmission was sent in 2008 and will reach the planet in early 2029 with the potential for a reply from any intelligent life on the planet by 2050.
A member of the Galaxy Zoo Forum (Djj) wrote this limerick for my Object of the Day on the same subject,
“Send a message in radio mime
That we’re here and we’re still in our prime;
Gliese five-eighty-one
Might be sombody’s sun —
We could hear back in forty years’ time!”
I will end this post with one of the more indulgent artist’s impressions of Gliese 581 g:
Gliese 581 g Credit: NASA
For our more technically minded readers, you can obtain the original announcement paper for Gliese 581 g here
The Eagle Nebula is one of the most well known regions in the universe having been snapped many times over the years by several telescopes including Hubble.
The latest images of the region come from the ESA’s Hershel Infrared Space Observatory and the XXM-Newton X-ray Observatory.
The Eagle Nebula seen by Hershel and XXM-Newton Credits: far-infrared: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium; X-ray: ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger
This image spans approximately 75 light years across the entirety of the nebula.
This image is a combination of data from both telescopes of the dense central region of the nebula. We can learn more about the information the image displays if we separate the data from each observatory, first lets have a look at the XXM-Newton X-ray data.
XXM data of the Eagle Nebula Credits: ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger
Each individual dot on the image is an X-ray source with the various colours indicating the energy of the X-rays being emitted by the source, red being the lowest energy (0.3-1keV) working up through medium energy sources shown in green (1-2keV) to the highest energy sources displayed in blue (2-8keV).
The XXM was observing the area to help determine the source of the Eagle Nebula’s strong emission. One theory suggests that a hidden supernova remnant could be supplying the nebula with large quantities of energy whilst remaining obscured by the nebula’s dense cloud. To help determine if this theory is valid the XXM is scouring the area in an attempt to detect any sign of a faint X-ray emission extending from the central region. The scientists believe that if the XXM doesn’t detect any more emitting material than has already been identified by previous searches using Sptizer and Chandra this will be strong support of the hidden SNR explanation.
Now lets examine the Hershel data:
Hershel's view of the Eagle Nebula Credits: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium
This displays the nebula in infra red wavelengths with 70 microns displayed in blue, 160 microns in green (both of these wavelengths were captured using filters in the PACS – Photodetector Array Camera - instrument) and finally 250 microns in red(images by SPIRE - Spectral and Photometric Imaging Receiver).
All these wavelengths are associated with very cold gas, indeed any gas displayed in blue here is just 40K above absolute zero down to that displayed in red which is a chilly 10K.
The twisted gas tendrils are still collapsing and will continue to form the next generation of stars for quite some time yet before the nebula finally disperses. Perhaps the most famous region within the nebula are the ‘Pillars of Creation’ which are in the above images which can be viewed just below the central point in the image (the eagle for which the nebula is named is located half way up the image on the left hand side, with its head pointing inwards). Indeed the Pillars are the central feature in one of the most recognisable image in all of astronomy:
The Pillars of Creation as seen by Hubble Credits: NASA/ESA/STScI, Hester & Scowen (Arizona State University)
The image was taken by Hubble in visible light using filters that isolate emission from excited hydrogen (Hα), singly ionised sulphur (SII) and doubly ionised oxygen (OIII). For scale, the tallest pillar is approximately four light years in height.
Now if we look at the same region in the infra red part of the spectrum (this time the data is provided by the ESO‘s, VLT’s ANTU telescope using the ISAAC instrument – yes that is quite a lot of acronyms), it looks completely different.
The Pillars of Creation as seen by ANTU Credits: VLT/ISAAC/McCaughrean & Andersen/AIP/ESO
At these wavelengths all but the densest regions of the Pillars are virtually transparent allowing us to gaze in wonder at the clumps of stars forming at the tips.
I leave you with this composite image, containing X-ray, visible and infra red data, enjoy.
Composite image of the Eagle Nebula Credits: far-infrared: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium; ESA/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger; optical: MPG/ESO; near-infrared: VLT/ISAAC/McCaughrean & Andersen/AIP/ESO
You can read more about this fantastic collection of images here.
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