Jika anda ternampak muka saya tengah TT (Teh Tarik) ni, bermakna anda telah selamat mengharungi 3 hari bumi tak jadi bergelap, dan tarikh 21hb Dis yang penuh tragis dan huru-hara (kononlah).

:-D

Nak ceritanya, Falak Online telah pun berpindah rumah. Bermula sekarang silalah kemaskini link ke WWW.FALAKONLINE.NET ,  tak perlulah letak apa-apa selepas tu, kerana ia akan redirect ke muka hadapan BARU yang sepatutnya.

Laman lama (yang anda lihat sekarang ni), InsyaAllah akan kekal untuk beberapa bulan mendatang. Ia akan menyenaraikan KESEMUA artikel lama saya di FO, bagi rujukan anda semua. Maka, kalau anda nak masih nak marah-marah kat saya berkenaan artikel "3 hari bergelap tu" , masih boleh berbuat demikian, saya terima dengan hati terbuka! :-)

Apa pun, InsyaAllah 2013 mendatang akan terdapat beberapa pembaharuan yang saya dan rakan-rakan Personaliti Astronomi lain usahakan, demi kemajuan bidang Astronomi di Malaysia.

Jom dan Selamat Datang Ke Tahun Baru 2013. 

Jemput masuk --->  WWW.FALAKONLINE.NET

 

Astronomy

Where, When, and How to See Mercury

Sky and Telescope - Thu, 30/10/2014 - 23:34

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.

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

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.

Categories: Astronomy

Auroras Aplenty on S&T‘s Iceland Tour

Sky and Telescope - Thu, 30/10/2014 - 22:11

Senior contributing editor Bob Naeye recently led a Sky & Telescope tour of Iceland, where 50 astro-tourists were treated to spectacular views of the Northern Lights.

The Sky & Telescope tour group gathers in front of Seljalandsfoss.
S&T: Robert Naeye

A group of about 50 astro-tourists were treated to four nights of auroras during a recently concluded week-long Sky & Telescope tour of Iceland. Conducted in partnership with Spears Travel, my fellow travelers and I also enjoyed spectacular waterfalls, an active geyser, and a uniquely idyllic culture.

“My wife and I both had a great time and are already planning our return trip,” says Mike Hoffert of Garden Grove, California.

“It was a wonderful trip and it was so nice to meet you as well. This trip met all my expectations,” adds Kathy Keith of Saint John, New Brunswick.

During an S&T aurora tour of Iceland in April 2013, we didn’t see any auroras until the final two nights of our trip, and even those displays were modest at best. This time around, the Weather Gods and the Sun were more cooperative.

Peter Chivers, a member of Sky & Telescope's recent tour to Iceland, captured this stunning shot of auroras in Icelandic skies.

On our first nighttime bus ride out, Monday, October 20th, we saw multiple aurora displays from a dark mountainous site about 25 miles east of the capital city Reykjavik. Although the auroras remained pale white in color, photos taken by tour members captured vivid greens and occasional splashes of red. I was fascinated by the speed at which the auroras changed form and how quickly they would come and go. At times, the auroras were all around us, and directly overhead. Given that most of the tour group members had never seen an aurora, I felt relief knowing that the trip was already a success in most of their minds. The skies that night were nearly crystal clear, and the temperature was cold but tolerable.

We also saw several auroras the following night from a site about 25 miles north of Reykjavik. But these auroras were much weaker than those on the previous night, and the sky was mostly cloudy. We gave up around midnight and headed back to our downtown Reykjavik hotel.

The stunning Gullfoss Waterfall.
S&T: Robert Naeye

Spears Travel put together a jam-packed itinerary of daytime activities but also arranged some optional tours and downtime. These activities are intended to insure a successful trip even if we don’t see any auroras. We were given a scenic tour of Reykjavik, which despite its relatively small metro area population of about 200,000, is a major cultural center with high-end museums, shops, and restaurants. The capital region contains about two-thirds of Iceland’s total population.

On Tuesday we did the famous Golden Circle tour, which includes stops at a rift valley where the North American and Eurasian tectonic plates are pulling apart (it’s also the site of the first Icelandic parliament about a millennium ago), a geothermal area with an active geyser (Strokkur), and a spectacular waterfall known as Gullfoss. This year, a beautiful rainbow seemed to hover over the falls. I found where the rainbow ended, but alas, there was no pot of gold.

On Thursday and Friday we toured the rugged south coast of Iceland, with towering cliffs, glaciers, and black-sand beaches. We briefly stopped at a farm just below the volcano Eyjafjallajökull, which despite its impossible-to-pronounce name gained worldwide notoriety in 2010 for disrupting air traffic over Europe for weeks. Other highlights included stops at two large waterfalls (Skogafoss and Seljalandsfoss) and a hike in Vatnajökull National Park.

Friendly and informative Icelandic guides served us during the entire trip. For example, our daytime guide, Elin Konrádsdóttir, told us that Iceland has prison space for only about 100 inmates, and that the maximum sentence for murder is 15 years. Despite this leniency, Iceland averages fewer than two murders per year, and the nation has very little crime, very few police, and no army or navy (but it is a member of NATO).

Joe Culler Jr.

We saw gorgeous auroral displays on our final two nights. On Thursday, we saw rapidly changing auroras from the tiny village of Kirkjubæjarklaustur (try pronouncing that!) in south-central Iceland. The following night we were staying at a hotel near Iceland’s famous Blue Lagoon geothermal spa. Clouds were rolling in around 11 p.m., so most of us (including me) went to bed, thinking there wasn’t much chance of seeing auroras. But several folks stayed up and were treated to what they described as the best auroral display of the trip.

The following morning we packed our belongings, enjoyed a refreshing 90-minute swim in the Blue Lagoon, and then headed to Keflavik International Airport for our flights home. Like most of my previous astro-tours, the best part of this trip was meeting so many interesting and friendly people. Most of our group came from the U.S., but we had two Canadians, two South Africans, two Australians, and a couple from Malta. The group bonded extremely well, and it was difficult to part ways after spending such a pleasant week together.

Overall, this was my fourth tour of Iceland, and I saw auroras on three of these trips (so I’m batting 0.750). I have enjoyed all of my trips, but this was the most successful of all due to the mostly good weather and near-perfect itinerary. S&T and Spears Travel are already thinking about future trips to Iceland, Chile, and other destinations. We welcome you to join us!

Join Sky & Telescope's planned tours for the 2016 and 2017 solar eclipses!

The post Auroras Aplenty on S&T‘s Iceland Tour appeared first on Sky & Telescope.

Categories: Astronomy

Mohon baca dan faham. Artikel FO: Ulasan kepada isu 3 hari bergelap dan kaitan...

Facebook - Thu, 30/10/2014 - 11:52
Mohon baca dan faham.

Artikel FO: Ulasan kepada isu 3 hari bergelap dan kaitan dengan solar storm

Mudah-mudahan tak crash lagi website FO lepas ni.. :-P

http://falakonline.net/semesta/2014/10/ulasan-kepada-isu-3-hari-bergelap-dan-kaitan-dengan-solar-storm/


Ulasan kepada isu 3 hari bergelap dan kaitan dengan solar storm
falakonline.net
Sejak kebelakangan ini, masyarakat Malaysia begitu kalut dengan berita terbaru dari NASA yang mengatakan Bumi akan mengalami 3 hari bergelap akibat daripada letusan di matahari. Begitu banyak kerat...
Categories: Astronomy

Sementara itu, jangan lupa SABTU ni, 1 November 2014, Jabatan Mufti Negeri Selan...

Facebook - Thu, 30/10/2014 - 09:15
Sementara itu, jangan lupa SABTU ni, 1 November 2014, Jabatan Mufti Negeri Selangor akan menganjurkan program bulanan mereka "Jom Teropong Angkasa 2014" di Dataran Kemerdekaan Shah Alam!

Tajuk bulan ini, tajuk ter-hot masa kini, kita bincang dan faham mengenai Isu 3 hari bergelap dan berkenalan dengan matahari, bersama-sama dgn bos FO sekali lagi.

Lepas syarahan, InsyaAllah jika langit comel, kita meneropong angkasa mengambil iktibar ayat 190 Surah Ali-Imran! Baru ohsem!

Jom kita jumpa di sana!

Untutk maklumat lanjut, sila hubungi Bahagian Falak, Jabatan Mufti Negeri Selangor di 03-55143738


Categories: Astronomy

Solar Eclipse Oct 23 2014 Collage

Sky and Telescope - Thu, 30/10/2014 - 03:54
Categories: Astronomy

Exoplanets for the Mind’s Eye

Sky and Telescope - Thu, 30/10/2014 - 03:32

You might call it wishful thinking, but here's how to "see" a dozen exoplanets in the fall evening sky.

Artist's conception of an extrasolar planet orbiting a star.
NASA

When I was a boy, I read a book that inspired a love of science, outer space, and adventure. The Wonderful Flight to the Mushroom Planet by Margaret Cameron featured two young boys, Chuck and David, who met up with the brilliant but eccentric Tyco Bass. Bass invented a special "stroboscopic polarizing filter" that allowed him to see a hidden planet named Basidium very near Earth. With his help, the boys built a spaceship, traveled there to solve a crisis, and returned safely home.

While it's unlikely Earth harbors a hidden planet, amateur astronomers of the far future may one day focus their filter-equipped telescopes on distant stars to spy planets that today require the most advanced techniques to photograph, let alone see. But we needn't walk away empty-handed in the present. Instead, we can better picture these alien worlds, if only indirectly, through acquaintance with their host stars. I'll explain in a minute.

In the transit method, a repeating dip in the star's brightness is caused by an orbiting extrasolar planet.
ESO

Extrasolar or exoplanets orbit stars other than the Sun. As of October 22, 2014, we know of an astonishing 1,832 of them. 1,151 gave themselves away when transiting or orbiting in front of their host stars. Astronomers look for regularly repeating dips in the star's light — usually less than 1% — that indicate shading from a transiting planet. Knowing the distance and diameter of the star, as well as the length of time the passing object dimmed the star’s light, they can determine the planet’s size and mass.

In the radial velocity method, the exoplanet's gravity causes the host star to move back and forth. Measuring the shift of the star's light toward blue and red yields information about the planet's mass and orbit. Both methods favor the discovery of massive, Jupiter-like worlds.
ESO

The radial velocity method, with 559 exoplanet discoveries to its credit, is the next most popular way to snag an alien world. Here, astronomers measure the slight wobble of the host star around the planet–star center of gravity caused by the gravitational tug of an orbiting planet. As the star swings toward the observer, the light leaving it is compressed toward the blue end of the spectrum. As the star moves away, its light is stretched or shifted toward the red end of the spectrum. Measuring these small shifts leads to information about a planet's orbit and mass.

Three relatively bright stars visible in the northern and northwestern sky in autumn have planetary companions including Kochab (Beta UMi), Gamma Cephei, and Epsilon Corona Borealis. Exoplanets take the star's name, followed by a lower case letter (b, c, d, etc.) if more than one planet is found orbiting the star. The map shows the sky facing north around 7 p.m. in early November. Click to enlarge.
Source: Stellarium

We can see six of the Sun's planets without optical aid, and the remaining two require us only to use binoculars. Though no one's seen an extrasolar planet, a small number have been photographed. As you'd expect, because of their distances and sizes, all appear as points of light. That shouldn't stop us from looking up and at least picturing them in our mind's eye, though.

Fomalhaut b is one of the few planets for which we have a direct image. These images were taken by the Hubble Space Telescope and show the exoplanet and rocky debris disk around Fomalhaut. Light from the star itself has been blocked out to better see its surroundings.
NASA/ESA

A surprising number of naked-eye stars have a planetary companion(s), including 1st-magnitude Fomalhaut and three 2nd-magnitude stars — Kochab in the Little Dipper, Hamal in Aries, and Leo's Algieba. There are presently about 30 in all.

The southern half of the fall sky has five, easy-to-see stars with extrasolar planets — Epsilon Tauri in the Hyades, Aries' brightest star Hamal, 4th-magnitude Upsilon Andromedae (with no fewer than four planets), a pair of planets around Epsilon Ceti, and bright Fomalhaut with its single planetary companion. The map shows the sky facing south around 8 p.m. local time in early November. Click to enlarge.
Source: Stellarium

For your viewing pleasure, here are maps showing a select group of 4th-magnitude and brighter stars that are accompanied by one or more exoplanets and visible in the autumn evening sky. The table below includes a few details about each to whet your appetite.

Wishing you a wonderful flight to a hidden world!

Name Mass  Discovered Detection method
Orbital Period Distance Epsilon CrB b 6.7 Jupiters 2012 Radial velocity 418 days 221 l-y Beta UMi b 6.1 J 2014 Radial velocity 522 days 131 l-y Gamma Cep Ab 1.85 J 2003 Radial velocity 903 days 45 l-y Epsilon Tau b 7.6 J 2007 Radial velocity 595 days 147 l-y Alpha Ari b 1.8 J 2011 Radial velocity 381 days 66 l-y Upsilon And b 0.6 J 1996 Radial velocity 4.6 days 44 l-y "              " c 1.8 J 1999 Radial velocity 238 days "     " "              " d 10.2 J 1999 Radial velocity 1,303 days "     " "              " e 1.1 J 2010 Radial velocity 3,849 days "     " Eta Ceti b 2.5 J 2014 Radial velocity 403 days 124 l-y "         " c 3.3 J 2014 Radial velocity 752 days "     " Fomalhaut b 3.0 J 2008 Direct imaging 320,000 days 25 l-y

Use a Sky & Telescope Star Wheel to guide your journey through the autumn skies!

The post Exoplanets for the Mind’s Eye appeared first on Sky & Telescope.

Categories: Astronomy

Jangan lupa kita jumpa di Planetarium Negara pada Sabtu, 8 Nov 2014 nanti. Insy...

Facebook - Wed, 29/10/2014 - 16:17
Jangan lupa kita jumpa di Planetarium Negara pada Sabtu, 8 Nov 2014 nanti.

InsyaAllah bos FO dijemput untuk menyampaikan syarahan ringkas bertajuk

"Life as an Amateur Astronomer"

Pada sesi 4.20pm - 5.20pm

Jommm


Foto Garis Masa
Starfinder Astronomical Society will celebrate its 10th anniversary on 8th November 2014 in conjunction with the “World Space Week” at Planetarium Negara, Kuala Lumpur. This celebration will be jointly organized with Planetarium Negara that they generously provide the venue for all the activities. We will have talks, observations, exhibition, sales, games, and performance during the event, which start from 3:00pm and end at 10:00pm. Besides promoting interest in astronomy, we hope that participants with similar interest can meet face-to-face in this event where they can share their experience, knowledge, and idea. 寻星天文学会将于2014年11月8日配合“世界太空周” 庆祝创会十周年。此庆祝活动是与国家天文馆联合举办。地点就是位于吉隆坡的国家天文馆。 当天的活动将有讲座,观星会,展览,销售,游戏和表演。活动将从下午3点 开始直至晚上10:00。这次活动除了促进出席者对天文学的认识,也希望借此机会让参与者互相交流从而分享经验、知识和理念。
Categories: Astronomy

Malam nanti, lepas Isya' Masih nak tengok mana Marikh sekarang? Ia berada betul...

Facebook - Wed, 29/10/2014 - 15:17
Malam nanti, lepas Isya'

Masih nak tengok mana Marikh sekarang? Ia berada betul-betul di bawah kedudukan Bulan, bersinar sebagai objek berwarna merah.

Zuhal dah tak nampak dah, terbenam sekitar Maghrib-Isya'

Bima Sakti pun dah makin rendah menjelang Isya'

1,2 bulan ni, langit sebelah Isya' akan kurang mengancam...

Tapi... jangan lupa pandang Timur, sekitar 10 malam kerana buruj Orion sudah kembali! jeng jeng jeng..

#FOSkywatch


Categories: Astronomy

Evolusi dan perubahan keadaan sunspot AR2192 sepanjang 6 hari lepas.

Facebook - Wed, 29/10/2014 - 10:50
Evolusi dan perubahan keadaan sunspot AR2192 sepanjang 6 hari lepas.


Foto Garis Masa
6 days evolution of sunspot AR2192. Missed 1 day due to tech error. https://www.flickr.com/photos/shahgazer/15631834206/
Categories: Astronomy

kaboomm.. Roket Antares yang dilancar semalam meletup dan terhempas.. https://...

Facebook - Wed, 29/10/2014 - 09:50
kaboomm..

Roket Antares yang dilancar semalam meletup dan terhempas..

https://www.youtube.com/watch?v=MVHDP8C5yD0


NASA rocket explodes seconds after launch in Virginia

An unmanned rocket carrying supplies to the International Space Station exploded seconds after liftoff Tuesday evening in Wallops Island, VA. The damage is t...
Categories: Astronomy

Pernah tengok permukaan matahari dari jarak dekat (selain dari kawasan sunspot)?...

Facebook - Wed, 29/10/2014 - 07:38
Pernah tengok permukaan matahari dari jarak dekat (selain dari kawasan sunspot)?

Cuba tengok foto ni! Setiap 'ketul' benda 'bulat-bulat' tu ialah gas plasma yang panas sedang membuak-buak naik turun dari kawasan dalam matahari!

Ia dipanggil 'granule'

Puratanya, setiap satu ketul granule tu sebesar 1500km, dan boleh wujud sekitar 8-20 jam sebelum ia hilang dan diganti dengan granule lain.


October 26, 2014
Categories: Astronomy

Inside the December 2014 Issue

Sky and Telescope - Wed, 29/10/2014 - 03:36
PURCHASE PRINT ISSUE | PURCHASE DIGITAL ISSUE | DOWNLOAD BACK ISSUES | SUBSCRIBE

Dark Oceans and Into Thin Air: Oh The Places Astronomers Go

As seen within Earth's abyssal oceans, sunlight isn't a requirement for life. Turns out the solar system contains multiple potential locations where distinct alien lifeforms might flourish. Caleb Scharf, astronomer, astrobiologist, and author of our December issue cover story, takes you to those fascinating worlds. Dark oceans aren't the only places you'll find astronomers going. Astronomy has long migrated from civilization into the most remote locations on the globe. Author Tom Gale takes you there, too: into the thin mountain air where telescopes image the cosmos at their best. For more astronomy destinations, check out the December issue, where Sue French guides a tour through Cassiopeia, Charles Wood shows you how to find the oldest lunar basins, and much more.

Feature Articles

NASA / JPL / DLR

A Universe of Dark Oceans
The icy bodies of the outer solar system might be teeming with life.
By Caleb Scharf 

Reviving Astronomy in a Small Nation
After a tumultuous period when interest in astronomy virtually disappeared, the flame of astronomy has reignited in Nicaragua.
By Julio Vannini

Into Thin Air
Astronomers’ continual quest for optimal seeing conditions has
ensured that leading observatories get built on ever-higher
mountaintops.
By Tom Gale

Visual Guide to the Cassiopeia A Supernova Remnant
Long thought unobservable, this important object displays
surprising detail through medium to large backyard telescopes.
By Howard Banich

Digging into PixInsight
Get more out of your astrophotos with this powerful software.
By Ron Wodaski

Beyond the Printed Page

Map of 2016 eclipse tour destinations.

Sky & Telescope 2016 and 2017 Eclipse Tours
Viewing a total solar eclipse tops an astronomer's bucket list, and you won't want to miss out on these.

Laniakea: Our Home Supercluster by Camille M. Carlisle
Find videos exploring our local cosmic structure.

Quark Nova Spotted in Cas A? by Shannon Hall
Two elements within supernova remnant Cassiopeia A hint at a second explosion.

Lunar Librations by Sean Walker
Librations and other lunar data for December 2014.

ALSO IN THIS ISSUE

NASA / JPL

Jupiter Comes into Its Own
The King of Planets rises high before midnight in late December.
By Fred Schaaf

The Starry Heavens
Clusters and nebulae abound in compact Cassiopeia.
By Sue French

Celestron Package: A Lot for a Little
An ensemble of Celestron equipment provides excellent visual and photographic performance.
By Rod Mollise

 

Table of Contents
See what else December's issue has to offer.

The post Inside the December 2014 Issue appeared first on Sky & Telescope.

Categories: Astronomy

Perlu ke bos FO menulis artikel baru untuk menjawab cerita 3 hari bergolap tu?...

Facebook - Mon, 27/10/2014 - 19:13
Perlu ke bos FO menulis artikel baru untuk menjawab cerita 3 hari bergolap tu?

Ce bagi pendapat. Timacih...
Categories: Astronomy

Two Exocomet Populations Around Beta Pictoris

Sky and Telescope - Mon, 27/10/2014 - 18:00

The comets in the infant planetary system around Beta Pictoris come from two families.

Eight years of measurements from the HARPS spectrograph in Chile have revealed two distinct populations of comets in the forming planetary system around Beta Pictoris, Flavien Kiefer (Paris Institute of Astrophysics) and colleagues report in the October 23rd Nature.

Artist's conception of the planet-forming disk around the star Beta Pictoris. The carbon-rich gas disk could be fed in part by the debris from small colliding bodies and the evaporation of comets.
Credit: NASA / FUSE / Lynette Cook

Astronomers already knew cometary bodies fill the disk around Beta Pic: work by members of the same team in the 1980s and 1990s found hints of evaporating bodies traversing in front of the star. These bodies block certain wavelengths of starlight when they pass between us and Beta Pic, leaving absorption features in the light that come and go over the course of several hours.

The new results are an analysis of 1,106 spectra taken from 2003 to 2011, containing variable calcium absorption features from an estimated 493 exocomets. (To avoid double-counting, the team only looked at one spectrum per day.) To make the signals clearer, the team averaged spectra over 30 minutes to boost the detections. Still, there are so many evaporating bodies in this infant planetary system that, in each 30-minute spectrum, there’s an average of six comets passing in front of the star.

What’s interesting about the new report is that these stargrazing exocomets fall into two distinct groups. Of the 252 bodies for which the team could calculate physical info, roughly half fall into each population. Population D (for “deep” absorption lines) all approach Beta Pic from the same direction and spew out more gas (the astronomers can tell because the coma tends to block more of the star’s disk). Population S (for “shallow” absorption lines) come from all directions and evaporate less — which is odd, because their wider absorption lines indicate that they come twice as close to the star as D exocomets do.

Why D bodies put out more gas is unclear. The team suggests that a larger body fragmented out in the disk, producing a population of newly minted comets with fresh, evaporatable material on their surfaces that all follow the same orbit — like the Kreutz family of sungrazers in the solar system. Or perhaps the D exocomets are just bigger.

On the other hand, the S bodies behave like “old exhausted” comets, the team says. Their orbits suggest that they might be controlled by a massive planet (perhaps Beta Pictoris b) that keeps sending them in around the star as they’re pushed into highly elongated orbits.

The team also found four comet-like features in spectra of the star HD 172555, which it reported in the January 2014 Astronomy & Astrophysics Letters. Both systems are in the same group of stars and a few tens of millions of years old. Perhaps long-term spectroscopic studies of other edge-on planetary systems might reveal comet transits, too.

 

Fun fact: The planet Beta Pictoris b was officially discovered in 2008, but members of this same team potentially saw its effects decades earlier. In 1995 the team reported light variations in observations taken from 1975 to 1992 that could be explained by a planet at least 6 Earth-Sun distances from Beta Pic and somewhere between 1.1 and 1.6 times Jupiter’s radius; Beta Pic b orbits at 9 Earth-Sun distances and is 1.7 Jupiter radii.

 

References:

F. Kiefer et al. “Two Families of Exocomets in the Beta Pictoris System.” Nature. October 23, 2014.

F. Kiefer et al. “Exocomets in the Circumstellar Gas Disk of HD 172555.” Astronomy & Astrophysics Letters. January 2014.

H. Beust et al. “The Beta Pictoris Circumstellar Disk.” Astronomy & Astrophysics. September 1990.

A. Lecavelier des Etanges et al. “Beta Pictoris: Evidence of Light Variations.” Astronomy & Astrophysics. July 1995.

The delightful autobiography of comet hunter Leslie Peltier, Starlight Nights, is available in print and as an eBook.

The post Two Exocomet Populations Around Beta Pictoris appeared first on Sky & Telescope.

Categories: Astronomy

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