Astronomy & Science

Closure Averted for World-Class Observatory

Sky&Telescope -

The University of Hawai'i, in partnership with the University of Arizona and Lockheed Martin, will sustain operations of the UKIRT infrared telescope.

UKIRT

Star trails above the UK Infrared Telescope.
Nik Szymanek

In a hopeful turn of events, the University of Hawai’i has assumed ownership of the 35-year-old United Kingdom Infrared Telescope (UKIRT). One of the world’s leading infrared observatories, UKIRT will continue surveying nearby brown dwarfs, distant supermassive black holes, and everything in between.

Despite high productivity, UKIRT faced closure when UK’s Science and Technology Facilities Council pulled funding in 2012. A few months later, UKIRT director Gary Davis posted an Announcement of Opportunity, basically putting the world-class observatory up for sale.

“This process is completely unprecedented,” Davis told Sky & Telescope at the time. “I can think of telescopes that have been pensioned off because they are old or small or on poor sites, but this is the first time that a productive, world-leading telescope has been in this situation.

Unprecedented or not, it worked. Scientific operations will continue now that the University of Hawai’i supports the facility in partnership with the University of Arizona and Lockheed Martin Space Technology Advanced Research and Development Laboratories.

A similar turnabout seems to be in place for the 15-meter James Clerk Maxwell Telescope, which observes submillimeter-wavelength emission from cold dust and gas within the solar system and in distant galaxies. Also placed on the chopping block in 2012, its for-sale announcement came on June 21, 2013. The latest update says JCMT operations will transfer early next year to the University of Hawai’i, in partnership with the East Asian Core Observatories Association.

Green Bank Telescope

The Green Bank Telescope received a recent funding reprieve, but it'll need more to survive.
NRAO

This news may cheer astronomers at a number of state-of-the-art observatories still facing closure. As funding funnels towards next-gen scopes such as ALMA, the European Extremely Large Telescope, the Thirty Meter Telescope, and the Square Kilometer Array, current observatories around the world are coming under budgetary fire.

The U.S. National Science Foundation announced in 2012 plans to divest from two radio telescopes, the Green Bank Telescope and the Very Long Baseline Array, as well as three optical telescopes from the Kitt Peak National Observatory. Though Green Bank received a $1 million boost from the West Virginia University, it will need more if it is to survive long-term. More recently, the University of California announced its intentions to stop funding the long-running Lick Observatory by 2018. The fate of all of these telescopes remains to be seen.

Find the history of the world's greatest telescopes between the digital covers of Sky & Telescope when you peruse our Seven-Decade Collection.

The post Closure Averted for World-Class Observatory appeared first on Sky & Telescope.

Tour November’s Sky: Cassiopeia

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As the evening sky wheels around in late autumn, a mythic drama plays out in the stars above. Taking center stage, almost directly overhead at nightfall, is Cassiopeia, the Queen.

Cassiopeia as rendered by Johannes Hevelius

In Roman mythology, Cassiopeia is a queen whose boasts about her beauty land her and her royal family in big trouble.
Source: Johannes Hevelius

During November, skygazers at mid-northern latitudes have front-row seats to one of the great dramas of Roman mythology. The royal family of boastful Cassiopeia and her husband Cepheus soar high overhead. Nearby is their daughter Andromeda, chained to a rock and seemingly doomed. But Perseus, the hero of this saga, swoops in to save her.

Follow these constellations throughout the night as they wheel around Polaris, the North Star. Also high up is Pegasus, the Winged Horse, easily recognized by the Great Square of stars that mark its upper body.

Meanwhile, the only planet visible immediately after sunset is Mars, lurking very low in the southwest. Venus and Saturn are both lost in the Sun's glare. If you are up around midnight, watch for Jupiter rising in the east.

Arriving around mid-month, right on schedule, is the Leonid meteor shower, so called because the streaks of these shooting stars appear to radiate from the constellation Leo. Normally it’s a pretty modest display best seen before dawn on the 17th and 18th.

You can get a personal tour of the stars and constellations overhead on November evenings by downloading the 7-minute-long stargazing podcast below.

http://www.kqimageserver.com/skytelpodcasts/SkyTour-November-2014.mp3
Download the podcast here.

There's no better guide to what's going on in nighttime sky than the November issue of Sky & Telescope magazine.

The post Tour November’s Sky: Cassiopeia appeared first on Sky & Telescope.

This Week’s Sky at a Glance, Oct. 31 – Nov. 8

Sky&Telescope -

Some daily sky sights among the ever-changing stars and planets. Mercury in its best dawn display for 2014 (Nov. 1)

Mercury is having its best dawn showing for 2014. See our article Where, When, and How to See Mercury, and please help publicize it! (The blue 10° scale is about the width of your fist held at arm's length.)

Mercury and Spica at dawn, Nov. 5, 2014Mercury and Spica in the dawn, Nov. 8, 2014 dawFriday, October 31

For Halloween, the first-quarter Moon shines in the south after dark. It's between Altair, very high to its upper right, and Fomalhaut, far down to its lower left.

Saturday, November 1

As the stars come out, Deneb is nearly straight overhead as seen from mid-northern latitudes. Brighter Vega is west of the zenith. Altair is farther from the zenith toward the south.

Sunday, November 2

Algol should be at its minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:07 p.m. EST (7:07 p.m. PST). Its fading and rebrightening take several additional hours before and after. Here's a comparison-star chart giving the magnitudes of three stars near Algol; use them to judge its changing brightness.

For all times of Algol's minima this month, good worldwide, see the November Sky & Telescope, page 51, or use our Algol predictor.

Monday, November 3

As autumn proceeds, the Great Square of Pegasus looms ever higher at nightfall. It now reaches its level position very high toward the south as early as 8 or 9 p.m. this week — with the Moon shining under its left side tonight (for North America).

Tuesday, November 4

As the stars come out, look high above the waxing gibbous Moon for the Great Square of Pegasus. It's standing on one corner.

Wednesday, November 5

Algol is at minimum light for a couple hours centered on 6:56 p.m. EST.

Thursday, November 6

Full Moon (exactly full at 5:23 p.m. Eastern Standard Time). The Moon shines far below the two or three brightest stars of Aries during the evening. Can you see the Pleiades through the moonlight? The delicate little cluster is well to the Moon's left.

Friday, November 7

The Moon, just past full, rises in the east at dusk. Once it climbs high, look for orange Aldebaran to its lower left and the Pleiades to its upper left.

Saturday, November 8

The waning gibbous Moon rises around the end of twilight. Look for Aldebaran not very far to its upper left. Higher above Aldebaran are the Pleiades.

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Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby; for an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Pocket Sky Atlas

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but it's still less than one per square degree on the sky. Also plotted are many hundreds of telescopic galaxies, star clusters, and nebulae.

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Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."

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This Week's Planet Roundup

Mercury is having its best dawn apparition of 2014 for skywatchers at mid-northern latitudes. It hangs low above the eastern horizon in mid-dawn, brightening slightly from magnitude –0.6 to –0.8 this week. Fainter Spica glimmers nearby. Don't confuse Mercury with Arcturus well off to the left in the east-northeast. See our article, Where, When, and How to See Mercury.

Venus is hidden the glare of the Sun.

Mars and Teapot, Nov. 7, 2014

Have you ever seen the summery Sagittarius Teapot in November? Binoculars will help you pick it out below Mars just as it departs for the year.

Mars (magnitude +0.9) remains in the southwest as twilight fades. Look for it very far below Altair.

Jupiter (magnitude –2.0, between Cancer and Leo) rises in the east-northeast around midnight standard time. By dawn it shines high in the south, with Regulus nearly a fist-width lower left of it.

Saturn is lost in the sunset.

Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are high in the southeast and south, respectively, shortly after dark now. See our finder charts for Uranus and Neptune online or in the September Sky & Telescope, page 50.

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All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time (UT, UTC, or GMT) minus 4 hours. Eastern Standard Time (EST) is UT minus 5 hours.

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“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”

— Neil deGrasse Tyson, 2014.

The post This Week’s Sky at a Glance, Oct. 31 – Nov. 8 appeared first on Sky & Telescope.

Ghostly Light From Dead Galaxies

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Astronomers are peering into a galaxy cluster’s past, using Hubble’s Frontier Fields to measure the light from ghost stars cast adrift in galaxy collisions.

Imagine you’re on a faraway planet where night skies are bereft of the thousands of stars we’re accustomed to on Earth. Instead, skies are dark but for the hazy wisps of dozens or even hundreds of nearby galaxies.

That’s the night sky you might see if you're orbiting a ghost star, long since pulled free from its host galaxy during a galactic encounter. In a crowded cluster like Abell 2744, a galaxy has a good chance of experiencing a glancing collision, merger, or full-on disruption. Cast adrift in intergalactic space, the remnant stars emit a faint glow known as intracluster light, and until now, it has remained mostly a subject of theory.

Galaxy cluster Abell 2744

This composite shows the massive galaxy cluster Abell 2744. The galaxies are imaged using Hubble and the Very Large Telescope in Chile, while Chandra images the hot X-ray gas (pink). The blue glow maps the cluster's dark matter.
NASA / ESA / J. Merten / D. Coe

The Hubble Space Telescope’s Frontier Fields, a multiyear undertaking to map six faraway galaxy clusters in exquisite detail, is changing that. The first to be imaged is Abell 2744, a cluster that had already earned the nickname Pandora’s Cluster for its violent past. It is the site of a near-simultaneous pile-up of four smaller clusters. Light from its hundreds of galaxies has traveled 3.5 billion years to reach Earth.

Now Mireia Montes and Ignacio Trujillo (University of La Laguna, Spain) have used Hubble’s long stare to construct visible-light and near-infrared color images of the cluster. They split these color images by brightness, so that they can examine the color not just of the luminous galaxies but also of the much fainter intracluster light.

“The authors say that the intracluster light is a not-well defined quantity, observationally speaking,” says theorist Emanuele Contini (University of Trieste, Italy). “I would say that observers do not have many other choices!” While theorists can track every star as they model a galaxy cluster’s evolution, observational astronomers must define intracluster light as any light below some threshold in surface brightness.

Given the incredibly faint threshold, few telescopes are capable of saying much about intracluster light other than that it exists. But in these Hubble observations, Montes and Trujillo can use the color of the cluster’s faintest glow to reveal the ghost stars’ age.

Compared to stars contained with the cluster’s galaxies, the ghost stars emit bluer light, implying a higher metal content. (Astronomers have an odd habit of defining metals as anything not hydrogen or helium. Generally, the more metals a star contains, the younger it is.) The ghost stars appear to be on average between 3 and 9 billion years younger than the stars within the cluster's galaxies, closer in age and metallicity to stars within a Milky Way-size galaxy.

When Montes and Trujillo calculate the total mass emitting the "ghost light", they find it's 6% or so of the cluster’s total stellar mass. In other words, more than a hundred billion Suns’ worth of stars are floating around between the cluster’s galaxies.

Knowing the mass and age of the cluster's ghost light, the authors propose a simplest-case scenario: sometime relatively recently in this cluster’s history, violent collisions tore apart between four and six Milky Way-size galaxies, scattering their stars into intergalactic space. Contini notes that this is undoubtedly a lower limit, since any given galaxy collision is more likely to strip some stars rather than utterly destroy the galaxy.

Montes and Trujillo plan similar studies to piece together the collision history for the Fronter Fields’ other five galaxy clusters. The duo will also expand their study of Abell 2744 to include Hubble’s ultraviolet observations, which can pin down the ghost stars’ ages with even higher precision, a step theorists and observational astronomers alike agree is necessary to understanding galaxy clusters’ violent pasts.

References

M. Montes & I. Trujillo. "Intracluster Light at the Frontier: A2744." Astrophysical Journal. October 20, 2014.

Learn more about what the Frontier Fields have in store for us in our January 2015 issue - subscribe now!

The post Ghostly Light From Dead Galaxies appeared first on Sky & Telescope.

Where, When, and How to See Mercury

Sky&Telescope -

The innermost planet is well known for its speedy motion around the Sun, but you can spot it early in November hovering over the eastern horizon before sunrise.

In Roman mythology, Mercury is the fleet-footed messenger of the gods. His planetary namesake is equally famous for quick movement. The innermost planet zips around the Sun in just 88 days. This orbital pep, combined with the planet's closeness to the Sun, gives Mercury a reputation of being difficult to spot in the sky.

Spotting Mercury in November 2014

Fast-moving Mercury is easy to spot if you know where and when to look. This week, head out before sunrise to spot it low in the east.
Sky & Telescope diagrams

But, really, it's not hard to see Mercury — and this coming week you'll have a chance to prove it to yourself.

Mercury is in the midst of its best morning appearance of the year. It's been rapidly climbing in the predawn twilight, and on November 1st its elongation (angular separation) from the Sun maxes at 18.7°.

That's not particularly favorable; the planet's greatest elongation can reach 28° at times. However, thanks to a favorable tilt of the ecliptic during northern autumn, these crisp mornings the planet is perched almost directly above the Sun.

How To See Mercury in November Mercury over Duluth, Minnesota

Although it was no match for the bright lights on grain elevators in Duluth, Minnesota, the planet Mercury (near top) still shone brightly after sunset on January 27, 2014.
Bob King

As the month begins, Mercury rises about 90 minutes before the Sun, and it climbs to about 10° above the horizon as twilight starts to brighten. (Your clenched fist, held at arm's length, covers roughly 10° of sky.) So find a spot with a clear, unobstructed view toward east, and then head out about an hour before dawn. Skygazers in the U.S. will be adjusting clocks on November 2nd, as we return to standard time; after that aim to be outside no later than about 5:30 a.m.

Mercury shines at magnitude –0.6 on November 1st, so it will be fairly easy to spot. Also look for the star Spica, fainter at 1st magnitude, a few degrees to the planet's lower right. As the days pass, Spica will climb higher and Mercury will slip — by November 8th their roles have reversed, with Spica higher up.

The planet brightens throughout November, as it rounds the Sun and becomes more fully illuminated from Earth's perspective. But dawn's twilight outpaces and soon overwhelms that modest gain. So plan to spot Mercury while you can — by eye during the next two weeks and using binoculars during the week afterward.

Add a comment below (especially if your a Mercury "first-timer") to let me know about your efforts to spot this elusive celestial target.

Want to hold the innermost planet in your hands? Check out Sky & Telescope's new, highly detailed Mercury globe.

The post Where, When, and How to See Mercury appeared first on Sky & Telescope.

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