NGC 346 is nestled within the Small Magellanic Cloud, a small satellite galaxy to our Milky Way.
Credit: NASA/ESA/STScI/ Gladys Kober
Just outside the Milky Way Galaxy, roughly 210,000 light-years from Earth, there is the dwarf galaxy known as the Small Magellanic Cloud (SMC). Measuring about 18,900 light-years in diameter and containing roughly 3 billion stars, the SMC and its counterpart – the Large Magellanic Cloud (LMC) – orbit the Milky Way as satellite galaxies. Scientists are particularly interested in these satellites because of what they can teach us about star formation and the process where galaxies evolve through mergers, which is something the Milky Way will do with these two galaxies someday.
Another interesting feature of the SMC is the spectacular star cluster known as NGC 346, located near the center of the brightest star-forming region in the SMC, the hydrogen-rich nebula designated N66. Yesterday, NASA released a new image of this star cluster acquired by the venerableHubble Space Telescope, which provides a unique and breathtaking view of this star cluster. These images were made possible thanks to Hubble’s sharp resolution and unique ability to make sensitive ultraviolet observations.
Artist view of an active supermassive black hole. Credit: ESO/L. Calçada
Astronomers examining a star cluster near Sgr A*, the Milky Way’s supermassive black hole, found that the cluster has some unusually young members for its location. That’s difficult to explain since the region so close to the powerful black hole is infused with powerful radiation and dominated by the black hole’s extremely powerful gravitational force. According to our understanding of stellar formation, young stars shouldn’t be there.
Astronomers always like to look at incredibly violent places. Violence, in the astronomical sense, makes for rare conditions that can explain much about our universe. One of the violent places that astronomers love to study is the center of our Milky Way galaxy. Now, astronomers from the Center for Astrophysics (CfA) at Harvard have come up with a new catalogue of some of the most intense areas near the galactic core. They hope it will increase our understanding of these potential star-forming regions – and help explain why so few stars are actually formed in them.
A "super star cluster", Westerlund 1, which is about 16,000 light-years from Earth. It can be found in the southern constellation of Ara. The picture was taken from the European Southern Observatory's VLT Survey Telescope. Credit: ESO/VPHAS+ Survey/N. Wright
The largest stars in the universe tend to be loners, and new research points to the reason why. Although massive stars are born in clusters of many smaller brethren, they quickly get kicked out, forced to spend their lives alone.
The brilliant tapestry of young stars flaring to life resembles a glittering fireworks display in this Hubble Space Telescope image. The sparkling centerpiece of this fireworks show is a giant cluster of thousands of stars called Westerlund 2. The cluster resides in a raucous stellar breeding ground known as Gum 29, located 20,000 light-years away from Earth in the constellation Carina. Hubble's Wide Field Camera 3 pierced through the dusty veil shrouding the stellar nursery in near-infrared light, giving astronomers a clear view of the nebula and the dense concentration of stars in the central cluster. The cluster measures between six light-years and 13 light-years across.
Credits: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI) and the Westerlund 2 Science Team
Westerlund 2 is a star cluster about 20,000 light years away. It’s young—only about one or two million years old—and its core contains some of the brightest and hottest stars we know of. Also some of the most massive ones.
There’s something unusual going on around the massive hot stars at the heart of Westerlund 2. There should be huge, churning clouds of gas and dust around those stars, and their neighbours, in the form of circumstellar disks.
But in Westerlund 2’s case, some of the stars have no disks.
Chart showing the M71 Globular Cluster. Credit: astronomycentral.co.uk
Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the unusual globular cluster known as Messier 71.
If you look up into the night sky, on a particularly clear night when there’s not a lot of bright lights nearby, you may be able to make out a series of faint objects. Similar to the Milky Way, that cloudy, ghostly band that reaches across the night sky, these small pockets of fuzzy light are in fact collections of stars located thousands of light years away.
Gaia mapping the stars of the Milky Way. Credit: ESA/ATG medialab; background: ESO/S. Brunier
In 2013, the European Space Agency (ESA) deployed the Gaia mission, a space observatory designed to measure the positions of movements of celestial bodies. For the past four years, Gaia has been studying distant stars, planets, comets, asteroids, quasars and other astronomical objects, and the data it has acquired will be used to construct the largest and most precise 3D space catalog ever made, totaling 1 billion objects.
Using data provided by Gaia, a team of international scientists conducted a study of the recently-discovered star cluster known as Gaia 1. Located about 15,000 light years from Earth and measuring some 29 light years in radius, much about this cluster has remained unknown. As such, this study helped place constraints on a number of mysteries of this star cluster, which include its age, metallicity and origin.
For the sake of their study, which recently appeared in the journal Astronomy and Astrophysics under the title “Detailed Chemical Abundance Analysis of the Thick Disk Star Cluster Gaia 1“, the team conducted a detailed chemical abundance study of Gaia 1 to determine its unknown parameters. From this, accurate estimates on its age and composition are likely to now be possible.
Sky map based on the first release of Gaia data (DR1). Credit: ESA/Gaia/DPAC/A. Moitinho & M. Barros, CENTRA – University of Lisbon.
This combined photometry also indicated that the cluster had a radius of about 29 light years and contained as much as 20,000 Solar Masses. However, further studies found that the cluster was actually far more metal-rich than previously thought. This indicated that Gaia 1 was likely to be significantly younger, with estimates now claiming that it was at least 3 billion years old.
In addition, these subsequent studies also raised the possibility that the cluster was extra-galactic in origin, based on the fact that it orbits about 5,500 light years (~1.7 kpc) above the Milky Way’s disk. To remedy this, the team – led by Andreas Koch of the University of Lancaster and the Center for Astronomy Heidelberg – used Gaia data in order to conduct a detailed study of just how metal-rich the cluster was to get a better idea of its age.
As they stated in their study: “[T]his work focuses on a detailed chemical abundance analysis of four red giant members of Gaia 1, based on high-resolution spectroscopy, which we complement by an investigation of the orbital properties of this transition object.” This consisted of measuring the abundances of 14 elements within these red giant stars, which were selected from the 2MASS survey.
What they determined was that the Gaia 1 was more metal poor than previously expected, which indicated that it is older than the revised age estimates indicated – between 3 billion and 5.3 billion years old. In addition, they also measured the proper motions and orbits of the four target stars, using data obtained from the fifth U.S. Naval Observatory CCD Astrograph Catalog (UCAC5).
This information revealed that in the course of their orbits, the four target stars would reach a maximum distance of 3,262 light years (1.0 kpc) above the galactic disk, which was an indication that they were not extra-galactic in origin. Last, but not least, they indicated that Gaia 1’s structure does not truly conform to that of a globular cluster, as it was originally designated. As they conclude in their study:
“This confirms that Gaia 1 is rather a massive and luminous open cluster than a low-mass globular cluster. Finally, orbital computations of the target stars bolster our chemical findings of Gaia 1’s present-day membership with the thick disk, even though it remains unclear, which mechanisms put it in that place.”
While this study has helped place constraints on one of a newly-discovered Gaia object, the team acknowledges that there is still much to be discovered about this star cluster. They also acknowledge that there is a margin of error when it comes to their study, and that further research is needed before Gaia 1 can be properly classified.
The band of light (the Milky Way) that is visible in the night sky, showing the stellar disk of our galaxy. Credit: Bob King
“However, the hint of a metallicity spread between different studies in the literature may point towards a more complex origin that could involve a once more massive progenitor,” they state. “Thus the question as to its exact formation and origin remains unclear and needs to await more data such as the precise and accurate parallaxes that Gaia can offer.”
This newly-discovered cluster, and all attempts to better understand it, are merely the tip of the iceberg when it comes to what the Gaia mission has revealed so far. The second official release of Gaia data – aka. Gaia DR2 – is scheduled to take place in April of 2018. This will be followed by a third release in 2020 and, barring any mission extensions, a fourth and final release in 2022.
Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at Messier 26 open star cluster. Enjoy!
Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so that others wouldn’t make the same mistake. Consisting of 100 objects, the Messier Catalog would come to be viewed by posterity as a major milestone in the study of Deep Space Objects.
One of these objects is Messier 26, an open star cluster located about 5,000 light years from the Earth in the direction of the Scutum Constellation. While somewhat faint compared to other objects that share its section of the sky, this star field remains a source of mystery to astronomers, thanks to what appears to be a low-density star field at its nucleus.
Description:
When this cloud of stars formed some 89 million years ago, it was probably far more compact than today’s size of a 22 light year span. At a happy distance of about 5,000 light years from our solar system, we can’t quite see into the nucleus to determine just how dense it may actually be because of an obscuring cloud of interstellar matter.
Image of the Messier 26 Open Star Cluster. Credit: Wikisky
However, we do know a little bit about the stars contained within it. As astronomer James Cuffey suggested in a paper titled “The Galactic Clusters NGC 6649 and NGC 6694“, which appeared in July 1940 issue of The Astrophysical Journal:
“The relations between color and apparent magnitude show that NGC 6694 contains a well-defined main sequence and a slight indication of a giant branch. A zone of low star density 3′ from the center of NGC 6694 is noted. The ratio between general and selective absorption is estimated from the available data on red color indices in obscured clusters. Although uncertain in many cases, the results tend to confirm the ratio predicted by the law of scattering.”
However boring a field of stars may look upon first encounter, studies are important to our understanding how our galaxy evolved and the timeline incurred. As Kayla Young of the Manhasset Science Research team said:
“Star Clusters are unique because all of the stars in the cluster essentially have the same age and are roughly the same distance from Earth. Therefore, the purpose was to determine if a correlation exists between mean absolute magnitude and age of a star cluster. The absolute magnitude for star cluster NGC 6694 was calculated to be about 1.34 + .9. Using the B-V (Photometric Analysis) data ages were also calculated. After a scatter plot was created, the line of best fit demonstrated an exponential relation between the age and absolute magnitude.”
The M26 Open Star Cluster. Credit: NOAO/AURA/NSF
History of Observation:
Messier 26 was first observed by Charles Messier himself on June 20th, 1764. As he wrote of the discovery at the time:
“I discovered another cluster of stars near Eta and Omicron in Antinous [now Alpha and Delta Scuti] among which there is one which is brighter than the others: with a refractor of three feet, it is not possible to distinguish them, it requires to employ a strong instrument: I saw them very well with a Gregorian telescope which magnified 104 times: among them one doesn’t see any nebulosity, but with a refractor of 3 feet and a half, these stars don’t appear individually, but in the form of a nebula; the diameter of that cluster may be 2 minutes of arc. I have determined its position with regard to the star o of Antinous, its right ascension is 278d 5′ 25″, and its declination 9d 38′ 14″ south.”
Later, Bode would report a few stars with nebulosity – a field that simply wouldn’t resolve to his telescope. William Herschel would spare it but only a brief glance, saying: “A cluster of scattered stars, not rich.” While John Herschel would later go on to class it with its NGC designation, it was Admiral Smyth who would most aptly describe M26 for the true galactic cluster we know it to be. As he wrote upon viewing it in April of 1835:
“A small and coarse, but bright, cluster of stars, preceding the left foot of Antinous, in a fine condensed part of the Milky Way; and it follows 2 Aquilae by only a half degree. The principle members of this group lie nearly in a vertical position with the equatorial line, and the place is that of a small pair in the south, or upper portion of the field [in telescope]. This neat double star is of the 9th and 10th magnitudes, with an angle [PA] = 48 deg, and is followed by an 8th [mag star], the largest [brightest] in the assemblage, by 4s. Altogether the object is pretty, and must, from all analogy, possess affinity among its various components; but the collocation and adjustment of these wondrous firmamental clusters, and their probable distances, almost stun our present faculties. There are many astral splashes in this crowded district of the Galaxy, among which fine specimens of what may be termed luminiferous ether, are met with.”
The location of Messier 26 within the Scutum Constellation. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)
Locating Messier 26:
Finding Messier 26 in binoculars is easy as far as location goes – but not so easy distinguishing it from the starfield. Begin with the constellation of Aquila and its brightest star – Alpha. As you move southwest, count the stars down the Eagle’s back. When you reach three you are at the boundary of the constellation of Scutum. While maps make Scutum’s stars appear easy to find, they really aren’t.
The next most easily distinguished star in the line in Alpha Scutii. Aim your binoculars or finderscope there and you’ll see northern Epsilon and southern Delta to the east. Messier 26 is slightly southeast of Delta and will appear as a slight compression in the starfield, and you will be able to resolve a few individual stars to larger ones. Using a finderscope, it will appear as a very vague brightening – perhaps not seen at all depending on your finder’s aperture.
In even a small telescope, however, you’ll be pleased with what you see! Medium magnification will light up this 8th magnitude galactic star cluster and mid-sized instruments will fully resolve it. Power up! See how many stars you can – and can’t – resolve in this dusty, curtained, distant beauty!
And here are the quick facts to help you on your way!
Object Name: Messier 26 Alternative Designations: M26, NGC 6694 Object Type: Open Galactic Star Cluster Constellation: Scutum Right Ascension: 18 : 45.2 (h:m) Declination: -09 : 24 (deg:m) Distance: 5.0 (kly) Visual Brightness: 8.0 (mag) Apparent Dimension: 15.0 (arc min)
Messier 25, shown in proximity to the Sagittarius Constellation. Credit: Wikisky
Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 25 open star cluster. Enjoy!
Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so that other astronomers wouldn’t make the same mistake. Consisting of 100 objects, the Messier Catalog has come to be viewed as a major milestone in the study of Deep Space Objects.
One of these objects is Messier 25, an open star cluster located in the direction of the Sagittarius Constellation. At a distance of about 2000 light years from Earth, it is one of the few Messier Objects that is visible to the naked eye (on a clear night when light conditions are favorable).
Description:
This galactic star cluster was originally discovered by Philippe Loys de Cheseaux in 1745 and included in Charles Messier’s catalog in 1764. Oddly enough, it was one of those curious objects that didn’t get cataloged by Sir John Herschel – therefore it never received a New General Catalog (NGC) number.
This is odd, considering that it was part of the 1777 catalog of Johann Elert Bode, observed by William Herschel in 1783, written about by Admiral Smyth in 1836 and even commented on by the Reverend Thomas William Webb in 1859! It was until J.L.E. Dreyer in 1908 that poor little M25 ended up getting added to the second Index Catalog.
Atlas Image mosaic of Messier 25,obtained as part of the Two Micron All Sky Survey (2MASS). Credit: Univ. of Mass./IPAC/Caltech/NASA/NSF
Cruising along peacefully about 2,000 light-years away from Earth, this little group of stars spans across about 19 light years of space. Caught inside of its influence are four giant stars – two of spectral type M and two of type G. As we know, it contains the variable star U Sagittarii, a Delta Cephei-type, which lets us know this group of 86 or so stars may have began life together as long ago as 90 million years.
But how many stars are really in there? If you’re using a large aperture telescope, you’re probably detecting the signature of several just beyond the threshold limits. And so has more recent scientific studies. According to a study by A.L. Tadross (et al.) of the National Research Institute of Astronomy and Geophysics:
“The young open star cluster M25 (IC 4725) is located in the direction of the galactic center in a crowded region, near much irregular absorption features on Sagittarius arm. This cluster has some difficult observing problems due to its southern location. The mass data available in the literature have been gathered to re investigate this cluster using most photometric tools to determine its main photometric parameters. More than 220 stars with mean reddening of 0.50 mag and absorption of 1.62 mag are found within the cluster.”
Core region of the Messier 25 open star cluster. Credit: Sergio Eguivar
“Combination of high-precision photometry and spectroscopy allows the detailed study of the upper main sequence in open clusters. We are carrying out a comprehensive study of a number of clusters containing Be stars in order to evaluate the likelihood that a significant number of Be stars form through mass exchange in a binary. Our first results show that most young open clusters contain blue stragglers. In spite of the small number of clusters so far analyzed, some trends are beginning to emerge.In younger open clusters, such as NGC 869 and NGC 663, there are many blue stragglers, most of which are not Be stars. In older clusters, such as IC 4725, the fraction of Be stars among blue stragglers is very high. Two Be blue stragglers are moderately strong X-ray sources, one of them being a confirmed X-ray binaries. Such objects must have formed through binary evolution. We discuss the contribution of mass transfer in a close binary to the formation of both blue stragglers and Be stars.”
History of Observation:
Perhaps we know more about it today than our historic antecedents, but our knowledge of its existence is owed to astronomers like Charles Messier, who took the time to catalog it. As he wrote in his notes:
“In the same night, June 20 to 21, 1764, I have determined the position of another star cluster in the vicinity of the two preceding, between the head and the extremity of the bow of Sagittarius, and almost on the same parallel as the two others: the closest known star is that of the sixth magnitude, the twenty-first of Sagittarius, in the catalog of Flamsteed: this cluster is composed of small stars which one sees with difficulty with an ordinary refractor of 3 feet: it doesn’t contain any nebulosity, and its extension may be 10 minutes of arc. I have determined its position by comparing with the star Mu Sagittarii; its right ascension has been found at 274d 25′, and its declination at 19d 5′ south.”
Finder Chart for M25 (also shown M8->M9, M16->M18, M20->M24 and M28). Credit: freestarcharts
Perhaps William Herschel understood there was more there to be seen, for he commented in his unpublished notes; “Very large, bright, stars and some small, faint ones; I counted 70, and there are many more within no considerable extent.”
Yet, it was Admiral Smyth who really understood what lay beyond. From his observations, he wrote:
“A loose cluster of large and small stars in the Galaxy, between the Archer’s head and Sobieski’s shield; of which a pair og 8th magnitudes, the principle of a set something in the form of a jew’s harp, are above registered. The gathering portion of the group assumes an arched form, and is thickly strewn in the south, on the upper part, where a pretty knot of minute glimmers occupies the center, with much star-dust around. It was discovered in 1764 by Messier, and estimated by him at 10′ in extent: it is 5 deg to the north-east of Mu Sagittarii, and nearly on the parallel of Beta Scorpii, which glimmers far away in the west.”
Locating Messier 25:
Finding Messier 25 with binoculars is quite easy. Simply start at the teapot “lid” star, Lambda, and aim about a fist width almost due north. Here you will encounter a a Cepheid variable – U Sagittarii. This one is a quick change artist, going from magnitude 6.3 to 7.1 in less than seven days, so although it is a cluster member, it may fade on you from time to time as a marker star!
Location of Messier 25 and other Deep Sky Objects in proximity to the Sagittarius Constellation. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)
M25 will appear a a loose, but bright association of stars in binoculars and as a faint hazy spot in binoculars – but behold incredible resolution in a telescope. You’ll love the different magnitudes, so stick to around low to medium magnifications to enjoy it most.
As always, here are the quick facts. Enjoy!
Object Name: Messier 25 Alternative Designations: M25, IC 4725 Object Type: Open Galactic Star Cluster Constellation: Sagittarius Right Ascension: 18 : 31.6 (h:m) Declination: -19 : 15 (deg:m) Distance: 2.0 (kly) Visual Brightness: 4.6 (mag) Apparent Dimension: 32.0 (arc min)
Composite image of the Eagle Nebula (Messier 16, or NGC 6611), based on images obtained with the Wide-Field Imager camera on the MPG/ESO 2.2-metre telescope at the La Silla Observatory. Credit: ESO
Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 16 open star cluster – aka. The Eagle Nebula (and a slew of other names). Enjoy!
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier began noticing a series of “nebulous objects” in the night sky. Hoping to ensure that other astronomers did not make the same mistake, he began compiling a list of these objects,. Known to posterity as the Messier Catalog, this list has come to be one of the most important milestones in the research of Deep Sky objects.
One of these objects it he Eagle Nebula (aka. NGC 661. The Star Queen Nebula and The Spire), a young open cluster of stars located in the Serpens constellation. The names “Eagle” and “Star Queen” refer to visual impressions of the dark silhouette near the center of the nebula. The nebula contains several active star-forming gas and dust regions, which includes the now-famous “Pillars of Creation“.
Description:
Located some 7,000 light years away in the next inner spiral arm of the Milky Way galaxy, the Eagle Nebula spans some 70 by 50 light years across. Born around 5.5 million years ago, this glittering swarm marks an area about 15 light years wide, and within the heart of this nebula is a cluster of stars and a region that has captured our imaginations like nothing else – the “Pillars of Creation”.
Here, star formation is going on. The dust clouds are illuminated by emission light, where high-energy radiation from its massive and hot young stars excited the particles of gas and makes them glow. Inside the pillars are Evaporating Gaseous Globules (EGGs), concentrations of gas that are emerging from the “womb” that about to become stars.
Wide-field IR view of the Eagle Nebula, showing its Stars, the Pillars, and the Eagle’s EGGs. Credit: ESO
These pockets of interstellar gas are dense enough to collapse under their own weight, forming young stars that continue to grow as they accumulate more and more mass from their surroundings. As their place of birth contracts gravitationally, the interior gas reaches its end and the intense radiation of bright young stars causes low density material to boil away.
These regions were first photographed by the Hubble Space Telescope in 1995. As Jeff Hester – a professor at Arizona State University and an investigator with the Hubble’s Wide Field and Planetary Camera 2 (WFPC2) – said of the discovery:
“For a long time astronomers have speculated about what processes control the sizes of stars – about why stars are the sizes that they are. Now in M16 we seem to be watching at least one such process at work right in front of our eyes.”
The Hubble has shown us what happens when all the gas boils away and only the EGGs are left. “It’s a bit like a wind storm in the desert,” said Hester. “As the wind blows away the lighter sand, heavier rocks buried in the sand are uncovered. But in M16, instead of rocks, the ultraviolet light is uncovering the denser egg-like globules of gas that surround stars that were forming inside the gigantic gas columns.”
The Eagle Nebula’s pillars of creation taken in 1995 (right) and 2015. The new image was obtained with the Wide Field Camera 3, installed by astronauts in 2009. Credit: Left: NASA, ESA/HST/Hubble Heritage Team/STScI, J. Hester and P. Scowen (Arizona State University).
And some of these EGGs are nothing more than what would appear to be tiny bumps and teardrops in space – but at least we are looking back in time to see what stars look like when they were first born. “This is the first time that we have actually seen the process of forming stars being uncovered by photoevaporation,” Hester emphasized. “In some ways it seems more like archaeology than astronomy. The ultraviolet light from nearby stars does the digging for us, and we study what is unearthed.”
History of Observation:
The star cluster associated with M16 (NGC 6611) was first discovered by Philippe Loys de Chéseaux in 1745-6. However, it was Charles Messier who was the very first to see the nebulosity associated with it. As he recorded in his notes:
“In the same night of June 3 to 4, 1764, I have discovered a cluster of small stars, mixed with a faint light, near the tail of Serpens, at little distance from the parallel of the star Zeta of that constellation: this cluster may have 8 minutes of arc in extension: with a weak refractor, these stars appear in the form of a nebula; but when employing a good instrument one distinguishes these stars, and one remarks in addition a nebulosity which contains three of these stars. I have determined the position of the middle of this cluster; its right ascension was 271d 15′ 3″, and its declination 13d 51′ 44″ south.”
Composite image of M16 from the Herschel telescope in far-infrared and XMM-Newton in X-ray. Credits: ESA/Herschel/PACS/SPIRE/Hill, Motte, HOBYS Key Programme Consortium/XMM-Newton/EPIC/XMM-Newton-SOC/Boulanger
Oddly enough, Sir William Herschel, who was famous for elaborating on Messier’s observations, didn’t seem to notice the nebula at all (according to his notes). And Admiral Smyth, who could always be counted on for flowery prose about stellar objects, just barely saw it as well:
“A scattered but fine large stellar cluster, on the nombril of Sobieski’s shield, in the Galaxy, discovered by Messier in 1764, and registered as a mass of small stars in the midst of a faint light. As the stars are disposed in numerous pairs among the evanescent points of more minute components, it forms a very pretty object in a telescope of tolerable capacity.”
But of course, the nebula isn’t an easy object to spot and its visibility on any given night depends greatly on sky conditions. As historical evidence suggest, only one of the two masters (Messier) caught it. So take a lesson from history and return to the sky many times. One day you’ll be rewarded!
Locating Messier 16:
One of the easiest ways to find M16 is to identify the constellation of Aquila and begin tracing the stars down the eagle’s back to Lambda. When you reach that point, continue to extend the line through to Alpha Scuti, then southwards towards Gamma Scuti. Aim your binoculars or image correct finderscope at Gamma and put it in the 7:00 position.
The location of M16, relative to the “Teapot” asterism in the Sagittarius constellation. Credit: constellation-guide.com
For those using a finderscope, M16 will easily show up as a faint haze. Even those using binoculars won’t miss it. If Gamma is in the lower left hand corner of your vision – then M16 is in the upper right hand. For all optics, you won’t be able to miss the open star cluster and the faint nebulosity of IC 4703 can be seen from dark sky locations.
Another way to find M16 is by first locating the “Teapot” asterism in Sagittarius constellation (see above), and then by following the line from the star Kaus Australis (Epsilon Sagittarii) – the brightest star in Sagittarius – to just east of Kaus Media (Delta Sagittarii). Another way to find the nebula is by extending a line from Lambda Scuti in Scutum constellation to Alpha Scuti, and then to the south to Gamma Scuti.
Those using large aperture telescopes will be able to see the nebula well, but sky conditions are everything when it comes to this one. The star cluster which is truly M16 will always be easy, but the nebula is a challenge.
And as always, here are the quick facts on M16 to help you get started:
Object Name: Messier 16 Alternative Designations: M16, NGC 6611, Eagle Nebula (IC 4703) Object Type: Open Star Cluster and Emission Nebula Constellation: Serpens (Cauda) Right Ascension: 18 : 18.8 (h:m) Declination: -13 : 47 (deg:m) Distance: 7.0 (kly) Visual Brightness: 6.4 (mag) Apparent Dimension: 7.0 (arc min)
And be sure to enjoy this video of the Eagle Nebula and the amazing photographs of the “Pillar of Creation”:
