Tag Archives: M13

CNYO Observing Log: Beaver Lake Nature Center, 18 September 2014

Greetings fellow astrophiles,

After a double wash-out for our scheduled August 8/15 event, CNYO made a triumphant return to Beaver Lake Nature Center for one last end-of-Summer public viewing session. While the local meteorologists and the Clear Sky Clock predicting clear, dark skies for the entire evening, the observing itself was still a bit touch-and-go until about 9:00 p.m., when the whole sky finally opened up.

Despite a small snafu with the Beaver Lake events calendar (or, specifically, our lack of presence on it for this rescheduled event), we still managed 10 attendees (and passed the word along to several people there for an event earlier in the evening – I’m also happy to report that Patricia’s attendance justified our meetup group event scheduling!). With four CNYO’ers (Bob Piekiel, Larry Slosberg, Christopher Schuck, and myself) and three scopes present (including Bob Piekiel’s Celestron NexStar 11, Larry Slosberg’s 12” New Moon Telescope Dob, and my 12.5” NMT Dob) this was a great chance for several of the new observers to ask all kinds of questions, learn all the mechanics of observing through someone else’s scope, and, of course, take in some great sights at their own pace.

The 7:00 p.m. setup started promising, with otherwise overcast conditions gradually giving way to clearings to the Northwest. That all changed for the worse around 8:00 p.m. (when everyone showed up), when those same NW skies closed right up again, gradually devouring Arcturus, Vega, and any other brighter stars one might align with. The next hour was goodness-challenged, giving us plenty of time to host a Q+A, show the scope workings, remark on the amount of reflected light from Syracuse, and swing right around to objects within the few sucker holes that opened. And when all looked lost (or unobservable), the 9:00 p.m. sky finally cleared right up to a near-perfect late Summer sky, complete with a noticeable Milky Way band, bright Summer Triangle, and a host of satellites, random meteors, and bright Summer Messiers.

As has been the case for nearly every public viewing session this year, all the new eyes were treated to some of the best the Summer and Fall have to offer. These include:

M13 – The bright globular (“globe” not “glob”) cluster in Hercules
M31/32 – The Andromeda Galaxy (and its brighter, more separated satellite M32)
M57 – The Ring Nebula in Lyra
Herschel’s Garnet Star – To show very clearly that many stars have identifiable colors when magnified
Albireo – To reinforce the color argument above and to show one of the prominent doubles in the Night Sky, right at the tip of Cygnus.
Alcor/Mizar – Did you know that Alcor/Mizar is actually a sextuple star system? Alcor is its own double, each in Mizar is a double, and recent data reveals that the Alcor pair is gravitationally bound to the Mizar quartet.

To the observing list was added a discussion of how to begin learning the constellations. As we’ve discussed at several sessions, the best place to start is due North, committing the circumpolar constellations to memory FIRST. For those unfamiliar, these are the six constellations that never set below the horizon from our latitude (Ursa Minor (Little Dipper), most or Ursa Major (Big Dipper), Cassiopeia, Cepheus, Draco, and Camelopardalis (and if you can find Camelopardalis, you’re ready for anything). We’ve even consolidated all of this material into one of our introductory brochures for your downloading and printing pleasure:

CNYO Guide For New Observers

To my own observing list was added a treat thanks to Bob’s perfect position on the rise of the Beaver Lake parking circle, as he managed to catch Uranus low on the Eastern horizon just before we packed up for the evening. Even with Syracuse’s glow dimming the view, Uranus is a clear sight either in a scope (as a slightly blue-green disc) or through a low-power finder scope.

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Closing at Beaver Lake (including one low-flyer).

We offer special thanks to the Beaver Lake staff, who were fine with us staying as late as we liked (although we still finished up around 10) and who found *all* the light switches for the parking lot. I suspect our next Beaver Lake event won’t happen until the Spring, meaning we hope to see you at one of Bob Piekiel’s Baltimore Woods sessions during the winter – unless we all get inspired to throw extra layers on and organize another winter observing session somewhere, in which case we hope to see you there as well!

CNYO Observing Log: Green Lakes State Park, 25 July & 15 August 2014

* Session 1 – 25 July 2014

Exactly 364 days after our last outing past the now-defunct Fayetteville Friendly’s, Bob Piekiel and I hosted another well-attended session in the large open (frisbee) field of Green Lakes State Park on July 25th. This Friday evening saw reasonably warm and dewy conditions and no small amount of bug spray. The generally young crowd (2/3’s in the mid-teen or younger) was treated to Bob and mine’s usual post-dusk schtick, early sights of Saturn and Vega, and then a small host of other celestial objects as the night grew darker (after many of the youngest were dragged away by schedule-conscious adults).

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Bob Piekiel inspecting the dusk skies during setup.

After setup, the race was on for one of us to find Saturn to make sure everyone had seen at least one planet before leaving. After a lucky run of star finding (Vega and Arcturus) to align his Celestron NexStar 11, Bob had a long planetary line behind him, leaving me to start the evening with my New Moon Telescopes 12.5″ Dob on Vega (giving my post-Saturn line a glimpse of increasing numbers of stars around Vega as it darkened). By the end of the Vega line, Saturn was obvious to all and Mars was just between widely-spaced branches, allowing us to fill in the planet views before 1/2 the attendees (and all the youngest observers) left just after 9:00 p.m.

The rest of the evening was the usual free-for-all. While the sky still wasn’t nearly dark enough for dedicated observing at 10:00 p.m., we were fortunate to have a remaining group with both great interest in astronomical phenomena and vivid imaginations to fill in the perceptual gaps left by distant Fayetteville lights and our own early event timing. The discussions around the scope were as well received as the objects themselves.

As you might expect, having a session almost exactly 1 year apart means that the “pick hits” of last year were very similar to the “pick hits” of this year. The only real difference was the swapping of one swiftly-moving planet (Venus) with another (Mars). Saturn, in that one year block, has slid only slightly from Virgo last year to Libra this year. As for my usual policy of presenting at least one from the list of standard types of objects at each session, my observing and lecture list was as follows:

* (Hopefully) One PlanetSaturn
* One StarVega in Lyra was the obvious choice, giving all an early view of how bright stars shimmer strongly upon magnification (and allowing us to show how the shape of the spiders holding up our secondary mirrors affects our views). At Bob’s request, we also threw in Herschel’s Garnet Star in Cepheus as an example of very strongly-colored stars in the night sky (after showing Albireo to demonstrate the same).
* One BinaryAlbireo in Cygnus. I also included epsilon Lyrae in Lyra as it was close to Vega. Alcor and Mizar in Ursa Major are also excellent for testing visual acuity among attendees (and the magnified view gives still more to say about double stars in our neighborhood).
* One Open ClusterThe Double Cluster (Caldwell 14) in Perseus
* One Globular ClusterM13 in Hercules
* One NebulaM57, The Ring Nebula in a href=”https://en.wikipedia.org/wiki/Lyra”>Lyra. The use of an inflating balloon to demonstrate how you can see through the middle of a well-inflated balloon but can’t see well through the edges is as clear an explanation of what the Ring Nebula is from our vantage point as any other I can think of.
* One GalaxyM31, The Andromeda Galaxy in Andromeda. Despite the closeness to the horizon, M32 and M110 were also visible to observers at low magnification.
* Anything Else? – we were treated to several dozen obvious satellites and at least one bright meteor tail before packing up.

* Session 2 – 15 August 2014

The week of August 11 – 17 will be remembered as an almost useless one for CNY amateur astronomy. The Perseids were not only washed out by the timing of the Full Moon, but also by the constant overcast conditions (mixed with a few interesting lightning storms). Planned sessions at Baltimore Woods, Beaver Lake Nature Center (rescheduled for August 21st!), and North Sportsman’s Club were all scrubbed.

Given the lousy conditions all week for nighttime observing, I was a bit hesitant to drive out to Bob Piekiel’s August 15th session at Green Lakes State Park (even with one scope, it’s a lot of gear to drag around for a session where it won’t be used). That said, the Clear Sky Clock indicated a potential opening in the 9-ish to 11-ish range and the s’mores weren’t going to eat themselves. The crowd of around 25 (all crowded around a fire pit that smelled of charred marshmallow) were ready to observe and full of questions and fun discussion, so the early views of Saturn, Vega, and Arcturus were enough to keep us all occupied.

Around 9:20 p.m., a small miracle occurred as a massive clearing of the sky swept South/SouthEast, taking with it all of the present clouds in a slow, straight band that eventually gave us views of the entire sky before closing back again around 10:30 p.m. The clear, steady 70 minutes were more than enough to allow us to re-scan last month’s observing list (all little changed since last month!).

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Old and new light – the end of the fire pit and inspecting flashlights.

With everyone departing soon after, we were left to take in a bit of the remaining fire in the pit (and our observing attire left to take in that burning wood smell) before giving the grounds one last scan with a bright flashlight before departing. A lousy evening turned into a fantastic (and slightly shortened) night for a Public Viewing Session. Kudos as always to Attilla Danko for his ever prescient Clear Sky Clock!

CNYO Observers Log: International Observe The Moon Night At Westhill School District, 12 October 2013

Greetings fellow astrophiles!

Larry Slosberg and Ryan Goodson took their New Moon Telescopes on the road to the Westhill School District for the October 12th International Observe The Moon Night (IOMN, facebook, twitter). With a fistful of our A Guide For Lunar Observing brochures in tow, both report that the near-or-exceeding 100 attendees were full of great questions and enjoyed close-up views of our nearest natural satellite.

CNYO was delighted to be a part of this local IOMN activity and strongly encourage other schools and local groups to do the same. The Moon is the easiest observing target we have, good at all magnifications (including no magnification) and all times of year. It has been a test for physical theories, the guide for calendars throughout human history, unwitting recipient of meteor impacts (still!) that might have made random Tuesdays quite hectic on Earth, muse of artists and musicians alike, and all the light needed for many a midnight hike. If you missed the “official” IOMN session, grab a pair of binos soon and give the Moon a gander!

Below are a collection of images from Larry Slosberg’s observing station (and one great image of the Moon), courtesy of Michelle Marzynski. Click on any image for the full-size version.

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While Larry kept the festivities mostly Moon-centric at his scope, Ryan reports having put many of the best objects in the mid-autumn night sky on full display, including The Andromeda Galaxy (M31), the globular cluster M13 in Hercules, the double stars Albireo (a colored pair in Cygnus) and Mizar/Alcor (a double that becomes a triple at moderate magnification in Ursa Major), the open cluster M39 (“everyone’s fave it seemed” – L.S.) in Cygnus, and finally the Ring Nebula (M57) and the Double-Double in Lyra.

For myself, I celebrated IOMN early from the comfort of a window seat at 36,000 ft. With luck, I hope to be on the ground and running yet another scope for next year’s IOMN session!

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CNYO Observing Log: Baltimore Woods, 27 September 2013

Greetings fellow astrophiles!

The September 27th Baltimore Woods session was notable for several reasons. On the down side, my drive to Marcellus through Fairmount was delayed when a minivan with far too many large dogs in it had one of its automatic windows dropped down to the delight of an ejected dog that bounced off my driver side door (my non-astro thought for the day – if your pets are your children, please use the child safety options built into your very modern vehicle!). On the up side, for the first time since March, a Baltimore Woods session started at 7 p.m. The skies were dark enough to begin seeing the brightest stars with ease and cold enough to freeze out the many bugs that frequent the BW Nature Center.

Attending scopes included Bob Piekiel‘s massive 16″ Meade GOTO (with some included heavy lifting by the two of us to get it set up and torn down), Larry Slosberg’s 12″ New Moon Telescope, and my 12.5″ NMT Dob (herein referred to as “Ruby”). A fourth scope appeared early in the evening with the first attending family, but ended up not getting too much use. Despite being a bit worse for wear, their “retail store” Stratus 60mm refractor scope surprised the owners (and kids) with a good view of a distant cellular tower and a fuzzy but noticeably “half-moon cookie” Venus (whatever description works is fine with me).

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Bob inspecting the Stratus 60mm.

The final size (25ish) of the crowd (and the number of first-time attendees) dictated the observables for the evening, with all of us sticking mostly to bright, easily identifiable objects. As for our local neighborhood, the good news was that more than half of the planets were out for the evening (counting the views of Earth). The bad news was that Venus and Saturn set early (both due to the time and the high trees along the Western horizon), leaving the very distant Uranus and Neptune as targets for later-night observers.

As has been my standard procedure, I picked one object from my standard list of “kinds of” objects so those at my scope would be sure to get a sampling of the types of objects we amateur astronomers look forward to looking at. My list included:

* (Hopefully) One Planet – From my (scope’s) vantage point, Venus and Saturn were impossible catches behind large trees. Neptune and Uranus were, for the entire viewing session, nestled within the glow of Marcellus (and Syracuse beyond), so I didn’t even bother attempting to find them. Bob, however, had at his disposal a massive GOTO, so the gathered crowd was able to take in at least one of the two distant planets (making them part of the way-less-than-1% of the entire planet who can claim the same).

* One Star – At Bob’s request, I gave special attention to Herschel’s Garnet Star (mu Cephei) in Cepheus. One of the real benefits of magnification through good optics (or long-exposure photography) is the appearance of color in many stars that are otherwise just too slightly colored to be noticeable to Naked Eye observers. While the different colors of the binary star Albireo are generally obvious to most people, the Garnet Star jumped out to everyone through every eyepiece as a very orange star. This red supergiant, affectionately known to some as Erakis, is BIG. Those who have seen the image below in one of our CNYO library lectures…

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The scale of familiar objects in our vicinity (click for the wikipedia version).

Will recognize Mu Cephei as the third star from right (in the “Big Block” 6) in the bottom of the image. Our own Sun peters out in Block 3. If a super race of aliens were to swap out our Sun for the Garnet Star, the outer edge of its plasma would engulf Jupiter and either engulf or roast Saturn. Big. Not only big, but old to boot. Mu Cephei is what is known as a “carbon star,” one that has nearly exhausted its helium (which is produced from all the fusion of hydrogen, which it then exhausted quite some time ago) and is now producing carbon in the star’s core. The near-exhaustion of the star’s fuel means that it’s likely only a few million years from going supernova (somewhere between a finger snap and ringing wine glass in cosmic terms) and is currently identified as a variable star for its subtle and erratically changing brightness.

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Mu Cephei, Cepheus, and surrounding constellations.

As you scour Cepheus some evening, do take the Garnet Star in. If you’re scanning randomly along the bottom of the barn, you can’t miss it!

* One BinaryAlbireo in Cygnus remains an easy favorite. Everyone saw Albireo A as slightly orange or yellow, while Albireo B appeared as slightly to “clearly” blue (clearly a demonstration of the importance of dark adaption and cone sensitivity in the retina). One point of interest is that we’re not entirely sure of Albireo is an optical binary (the two just appear close, but one is much farther away than the other as projected onto our two-dimensional sheet of the Night Sky) or a gravitationally-bound binary pair. If gravitationally-bound, the two are likely far from one another, with the orbital dance occurring over 100,000 or more years.

* One Open Cluster – The Double Cluster (Caldwell 14) in Perseus

* One Globular Cluster – The ever-obvious M13 in Hercules

* One Nebula – The Veil Nebula in Cygnus – typically, this would be considered one of the less-easy objects for a new observer to make out. Through an OII filter, however, the wispy-ness jumps out and new observers, with a little patience, can even see the curvature of each fragment well enough to know where the Veil must be radiating from.

* One Galaxy – M31, The Andromeda Galaxy in Andromeda (and M32 and M110), which were easy for all to spot with a little scope nudging.

As has become the norm recently, I packed up Ruby around 9:30 p.m. and pulled out the Canon T3i and tripod for an extended session of scope-less astrophotography. Three highlights include a very discernible Milky Way, complete with Great Rift, from opposite the direction of Marcellus…

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The Milky Way (plus one bright plane and one dim satellite). Click for a larger version.

A dimmer part of the Milky Way that seemed to radiate from (and be washed out by) Marcellus…

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The Milky Way and Marcellus (plus a dim plane (dashed line) and dim satellite). Click for a larger version.

And a quite decent view of the varied objects in the vicinity of the constellation Perseus (in the pocket between the two trees and closer to the left tree), including the components of the Double Cluster, NGC 884 and 869 (the fuzzy splotches at the base of the small necklace – 1/3 over from the left edge and 1/4 down the image).

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Perseus, NGC 884, and NGC 869. Click for a larger version.

I packed it in around 10:00 p.m. in great anticipation! Within the glow of Marcellus lay the Pleiades (M45) and just a hint of its closer cousin the Hyades in the head of Taurus the Bull. These objects have likely served as markers for many millennia that the clear, dark, steady, and uncomfortably cold night skies of winter approach.

A Busy Day For Science @ NASA News – Voyager 1 Flies Out And Star Clusters Zoom In

Greetings fellow astrophiles!

There are untold numbers of places online that provide all kinds of astronomy news. The CNYO twitter feed is pushing 200 (following, that is. Still working on the follower count) accounts that range from UK Astronomy Clubs (they are exceptionally well organized on the other side of the pond) to equipment vendors to NASA astronauts. The same goes for RSS feeds from astronomy-centric news services, facebook groups, online magazines (or paper magazines with significant online contents), and a multitude of individuals hosting blog sites that report their own observing, study the news for proper amateur digestion, and generally produce really great content.

All that said, there is a lot of the same news online. With a large twitter feed count, you’ll see the same story a half-dozen times within an hour of its official reporting. Imagine following all the major news services to have them all post the same Associated Press tweet over and over and over again. One comes to question the veracity of the news services who happen to post articles hours or days after everyone else.

I subscribed a year ago to the NASA News Release Email List in the hopes of catching all of the major NASA happenings from the original source. The list is free to subscribe to and pumps out about 3000 news releases a year (some days being MUCH busier than others).

One can make their own subscription official by following the text at the footer of all their messages:

NASA news releases and other information are available automatically by sending an e-mail message with the subject line subscribe to hqnews-request@newsletters.nasa.gov. 
To unsubscribe from the list, send an e-mail message with the subject line unsubscribe to hqnews-request@newsletters.nasa.gov.

This past September 12 was a banner day for NASA News, as NASA made the official announcement of Voyager 1’s departure (sort of) from the Solar System and Hubble scientists reported the largest yet observed cluster of globular clusters (imagine having multiple M13’s in the same low-power field of view!) – featuring a rare image to complement the standard text-only announcements. I’ve included the two releases below (with an extra image showing the position of Voyager 1 – including an actual image of the distant traveler obtained using the Very Long Baseline Array (VLBA) and Green Bank Telescope (GBT).

Dwayne Brown – Headquarters, Washington – 202-358-1726 – dwayne.c.brown@nasa.gov

Jia-Rui C. Cook – Jet Propulsion Laboratory, Pasadena, Calif. – 818-354-0850 – jccook@jpl.nasa.gov

RELEASE 13-280 – NASA Spacecraft Embarks on Historic Journey into Interstellar Space

NASA’s Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space. The 36-year-old probe is about 12 billion miles (19 billion kilometers) from our sun.

New and unexpected data indicate Voyager 1 has been traveling for about one year through plasma, or ionized gas, present in the space between stars. Voyager is in a transitional region immediately outside the solar bubble, where some effects from our sun are still evident. A report on the analysis of this new data, an effort led by Don Gurnett and the plasma wave science team at the University of Iowa, Iowa City, is published in Thursday’s edition of the journal Science.

“Now that we have new, key data, we believe this is mankind’s historic leap into interstellar space,” said Ed Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. “The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we’ve all been asking — ‘Are we there yet?’ Yes, we are.”

Voyager 1 first detected the increased pressure of interstellar space on the heliosphere, the bubble of charged particles surrounding the sun that reaches far beyond the outer planets, in 2004. Scientists then ramped up their search for evidence of the spacecraft’s interstellar arrival, knowing the data analysis and interpretation could take months or years.

Voyager 1 does not have a working plasma sensor, so scientists needed a different way to measure the spacecraft’s plasma environment to make a definitive determination of its location. A coronal mass ejection, or a massive burst of solar wind and magnetic fields, that erupted from the sun in March 2012 provided scientists the data they needed. When this unexpected gift from the sun eventually arrived at Voyager 1’s location 13 months later, in April 2013, the plasma around the spacecraft began to vibrate like a violin string. On April 9, Voyager 1’s plasma wave instrument detected the movement. The pitch of the oscillations helped scientists determine the density of the plasma. The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space.

The plasma wave science team reviewed its data and found an earlier, fainter set of oscillations in October and November 2012. Through extrapolation of measured plasma densities from both events, the team determined Voyager 1 first entered interstellar space in August 2012.

“We literally jumped out of our seats when we saw these oscillations in our data — they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble,” Gurnett said. “Clearly we had passed through the heliopause, which is the long-hypothesized boundary between the solar plasma and the interstellar plasma.”

The new plasma data suggested a timeframe consistent with abrupt, durable changes in the density of energetic particles that were first detected on Aug. 25, 2012. The Voyager team generally accepts this date as the date of interstellar arrival. The charged particle and plasma changes were what would have been expected during a crossing of the heliopause.

“The team’s hard work to build durable spacecraft and carefully manage the Voyager spacecraft’s limited resources paid off in another first for NASA and humanity,” said Suzanne Dodd, Voyager project manager, based at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif. “We expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020. We can’t wait to see what the Voyager instruments show us next about deep space.”

Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft. It is about 9.5 billion miles (15 billion kilometers) away from our sun.

Voyager mission controllers still talk to or receive data from Voyager 1 and Voyager 2 every day, though the emitted signals are currently very dim, at about 23 watts — the power of a refrigerator light bulb. By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt. Data from Voyager 1’s instruments are transmitted to Earth typically at 160 bits per second, and captured by 34- and 70-meter NASA Deep Space Network (DSN) stations. Traveling at the speed of light, a signal from Voyager 1 takes about 17 hours to travel to Earth. After the data are transmitted to JPL and processed by the science teams, Voyager data are made publicly available.

“Voyager has boldly gone where no probe has gone before, marking one of the most significant technological achievements in the annals of the history of science, and adding a new chapter in human scientific dreams and endeavors,” said John Grunsfeld, NASA’s associate administrator for science in Washington. “Perhaps some future deep space explorers will catch up with Voyager, our first interstellar envoy, and reflect on how this intrepid spacecraft helped enable their journey.”

Scientists do not know when Voyager 1 will reach the undisturbed part of interstellar space where there is no influence from our sun. They also are not certain when Voyager 2 is expected to cross into interstellar space, but they believe it is not very far behind.

JPL built and operates the twin Voyager spacecraft. The Voyagers Interstellar Mission is a part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA’s Science Mission Directorate in Washington. NASA’s DSN, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions.

The cost of the Voyager 1 and Voyager 2 missions — including launch, mission operations and the spacecraft’s nuclear batteries, which were provided by the Department of Energy — is about $988 million through September.

For a sound file of the oscillations detected by Voyager in interstellar space, animations and other information, visit: www.nasa.gov/voyager

For an image of the radio signal from Voyager 1 on Feb. 21 by the National Radio Astronomy Observatory’s Very Long Baseline Array, which links telescopes from Hawaii to St. Croix, visit: www.nrao.edu (image below – click for a large version).

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J.D. Harrington – Headquarters, Washington – 202-358-5241 – j.d.harrington@nasa.gov

Ray Villard – Space Telescope Science Institute, Baltimore, Md. – 410-338-4514 – villard@stsci.edu

RELEASE 13-282 – Hubble Uncovers Largest Known Group of Star Clusters, Clues to Dark Matter

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Hubble Space Telescope image of largest known population of globular clusters, in Abell 1689 galaxy grouping. Image Credit: NASA/ESA

NASA’s Hubble Space Telescope has uncovered the largest known population of globular star clusters, an estimated 160,000, swarming like bees inside the crowded core of the giant grouping of galaxies known as Abell 1689.

An international team of astronomers used Hubble’s Advanced Camera for Surveys to discover this bounty of stellar fossils and confirm such compact groupings can be used as reliable tracers for dark matter, the invisible gravitational scaffolding on which galaxies are built.

“We show how the relationship between globular clusters and dark matter depends on the distance from the center of the galaxy grouping,” Karla Alamo-Martinez of the Center for Radio Astronomy and Astrophysics of the National Autonomous University of Mexico in Morelia. “In other words, if you know how many globular clusters are within a certain distance, we can give you an estimate of the amount of dark matter.”

Alamo-Martinez is lead author of a paper on the findings published online Sept. 10 and appearing in the Sept. 20 print edition of The Astrophysical Journal, and part of a team led by John Blakeslee of National Research Council Canada’s Herzberg Institute of Astrophysics at the Dominion Radio Astrophysical Observatory in Victoria, British Columbia.

Globular clusters, dense bunches of hundreds of thousands of stars, are the homesteaders of galaxies. They contain some of the oldest surviving stars in the universe. Almost 95 percent of globular cluster formation occurred within the first 1 billion to 2 billion years after our universe was born in the theorized Big Bang 13.8 billion years ago.

Studying globular clusters is critical to understanding the early, intense star-forming events that mark galaxy formation. Understanding dark matter can yield clues on how large structures such as galaxies and galaxy clusters were assembled billions of years ago.

The globular star cluster in Abell 1689 is roughly twice as large as any other population found in previous globular cluster surveys — in comparison, our Milky Way galaxy hosts about 150 — and constitutes the most distant such systems ever studied, at 2.25 billion light-years away. The Hubble study shows most of the globular clusters in Abell 1689 formed near the center of the galaxy grouping, which contains a deep well of dark matter. The farther away from the galaxy core Hubble looked, the fewer globular clusters it detected. This observation corresponded with a comparable drop in the amount of dark matter, based on previous research.

“The globular clusters are fossils of the earliest star formation in Abell 1689, and our work shows they were very efficient in forming in the denser regions of dark matter near the center of the galaxy cluster,” Blakeslee said. “Our findings are consistent with studies of globular clusters in other galaxy clusters, but extend our knowledge to regions of higher dark matter density.”

Peering deep inside the heart of Abell 1689, Hubble detected the visible-light glow of 10,000 globular clusters, some as dim as 29th magnitude, which is 1 one-billionth the faintness of the dimmest star that can be seen with the naked eye. Based on that number, Blakeslee’s team estimated that more than 160,000 globular clusters are huddled within a diameter of 2.4 million light-years.

“Even though we are looking deep into the cluster, we’re only seeing the brightest globular clusters, and only near the center of Abell 1689 where Hubble was pointed,” he said.

For images and more information about the Abell 1689, visit:

www.nasa.gov/hubble or hubblesite.org/news/2013/36

The NASA News Release service is a great way to keep track of goings on in the nation’s space program, but goes much farther into all areas of NASA research, including climate research, geology, engineering, and administration. I encourage interested parties to sign up and get at least some of their space science news first-hand – then complain about all the twitter feeds taking so many minutes to report the same.