Author(s): Charles Day

At low temperatures the resistance of a layered magnetic semiconductor shoots up and down in response to an increasing magnetic field.

[Physics 18, s14] Published Thu Jan 30, 2025

Kfir Simon, taken from Tivoli Farm, Namibia RCW 85 is a faint emission nebula in the southern constellation of Centaurus. The designation “RCW” comes from a catalog of Hα emission regions published in 1960 by a trio of researchers working in Australia under the astronomer Bart Bok: Alexander Rodgers, Colin Campbell, and John Whiteoak. ThisContinue reading "A southern target"

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Chile is home to SOME of the world’s best skies — and some of the world’s most advanced instruments to observe them. From the radio telescope array charting complex chemistry in Titan’s atmosphere to the telescopes that pinpointed the neutron star merger last year, Chilean observatories play a starring role in today’s groundbreaking discoveries. ManyContinue reading "The Astronomy in Chile Educator Ambassadors Program: Sharing the skies above Chile"

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Author(s): Charles Day

Simulations demonstrate that light can be confined within a scattering medium in a way similar to electrons in a disordered metal.

[Physics 18, s10] Published Wed Jan 29, 2025

Author(s): Ryan Wilkinson

An algorithm allows the states of certain quantum systems to be determined from data more quickly than was previously possible.

[Physics 18, s17] Published Tue Jan 28, 2025

After our Sun becomes a white dwarf and cools completely, what will be left? Richard LivitskiSeal Beach, California Our Sun will become a white dwarf in about 7 billion years. At that point, it will no longer produce energy through nuclear fusion, having exhausted its fuel (hydrogen and helium). Just like the embers of anContinue reading "After our Sun becomes a white dwarf and cools completely, what will be left?"

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Josh Dury, taken from the Mendip Hills in Somerset, U.K. The International Space Station sails through the sky in this long exposure, its arc in this long exposure intersecting the ongoing “planet parade” along the ecliptic, including (left to right) Mars, Jupiter, Venus, and Saturn. To view the photographer’s annotated version highlighting the planets, clickContinue reading "Parade crasher"

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Author(s): David C. Cassidy

Arthur Compton’s results convinced most skeptics that in some experiments, light can act like a stream of particles.

[Physics 18, 18] Published Mon Jan 27, 2025

In this episode, Dave Eicher invites you to go out and spot the many planets currently in our night sky. You’ll see four of the five planets visible without optical aid. Venus and Saturn are in the west; Jupiter lies overhead; and Mars is in the east. Opportunities to see so many easy-to-spot planets don’tContinue reading "A Parade of Planets: This Week in Astronomy with Dave Eicher"

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The U.S.’s return to the Moon with NASA’s Artemis program will not be a mere stroll in the park. Instead it will be a perilous journey to a lunar location representing one of the most extreme environments in the solar system. For the Artemis program astronauts, walking on the Moon will require new ways ofContinue reading "Astronauts on NASA’s Artemis mission to the Moon will need better boots — here’s why"

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A proposed massive hydrogen-fuel production project in Chile has astronomers galvanized in concern and opposition. One astronomer calls the possible Chilean facility a “nightmare” for the Paranal Observatory’s dark skies. One study has found that Paranal, located in Chile’s Atacama Desert, has the darkest skies of any major astronomical research site. That would change ifContinue reading "Green hydrogen project threatens pristine Paranal skies in Chile"

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Chris Cook from Long Beach, California The McMath-Pierce Solar Telescope stands beneath a dark, moonless sky at Kitt Peak National Observatory in Arizona. The photographer took 90 one-minute exposures with a Canon DSLR at f/2.8 and ISO 2500.

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NASA Administrator Bill Nelson stepped down on Monday, Jan. 20, after President Donald Trump was inaugurated, and the departing space agency chief had some words of advice for his replacement. In a letter addressed to the next NASA administrator — who, if Trump’s nomination is confirmed, will be Shift4 CEO and SpaceX ally Jared Isaacman — NelsonContinue reading "NASA administrator steps down, urges continuity under new leadership"

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Author(s): Mark Buchanan

Conventional theory has trouble predicting the conditions that will cause a liquid to boil, but a neural-network-based approach performs better.

[Physics 18, 17] Published Fri Jan 24, 2025

Last week at the 245th meeting of the American Astronomical Society in National Harbor, Maryland, astronomers presented some of their most recent and exciting finds from the James Webb Space Telescope (JWST). One such discovery was the identification of the most distant so-called core-collapse supernova ever confirmed. These explosions mark the end of life for massiveContinue reading "Astronomers find the most distant supernova yet"

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Friday, January 24The Moon passes 0.3° south of the bright red giant star Antares at 7 P.M. EST. However, the pair isn’t visible this evening, as they’ll rise in the early-morning sky, so we’ll feature them tomorrow.  Tonight, we’ll focus instead on Mars. The Red Planet recently reached opposition and is still visible essentially allContinue reading "The Sky This Week from January 24 to 31: The Moon mingles with Antares"

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Author(s): Susan Curtis

Physicists have demonstrated a quantum machine that could reduce errors in quantum computers by ensuring that the qubits they use remain in their initial state before a calculation starts.

[Physics 18, 16] Published Thu Jan 23, 2025

Author(s): Katherine Wright

Seong Jim Kim and Myoung-Woon Moon of the Korea Institute of Science and Technology have developed a device that can “vacuum” up tiny pieces of plastic floating on the surface of a body of water.

[Physics 18, 6] Published Thu Jan 23, 2025

Author(s): Rachel Berkowitz

Roughing up the surfaces of particles in a colloidal system can smooth its transition into a glassy state.

[Physics 18, s11] Published Thu Jan 23, 2025

A nearby star that may host a planet or two could provide a clue about whether planets orbiting the smallest stars can survive the bullying of their suns.  In a press conference last week at the 245th meeting of the American Astronomical Society, Scott Wolk of the Smithsonian Astrophysical Observatory presented his findings on WolfContinue reading "Could planets orbiting red dwarfs host life?"

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Deeper look Imm Astrophotography SeriesOnalaska, TX The 750 Best Deep Sky Objects (Reachable From the Northern Hemisphere) by amateur astronomer Gary Imm is a precise visual guide to deep-sky objects, complete with rankings and images for every target. This 88-page reference gives readers a detailed list of where the targets are in the Northern HemisphereContinue reading "Cozy up with new astronomy products this month"

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Huang Dandan, taken from Yulong Latso, Gangzi, Sichuan Province, China The Milky Way, zodiacal light, and airglow are all visible in this all-sky mosaic, capturing the glow of phenomena on planetary, solar system, and galactic scales. The photographer used an astromodified Sony mirrorless camera and 11mm fisheye lens to capture this mosaic, taking 20-second exposuresContinue reading "All aglow"

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Author(s): Jennifer Ouellette

In one of his annus mirabilis papers, Einstein explained the photoelectric effect by considering light as a stream of energy quanta—which were later called photons.

[Physics 18, 15] Published Wed Jan 22, 2025

On Jan. 2, the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, announced the discovery of an unusual asteroid, designated 2018 CN41. First identified and submitted by a citizen scientist, the object’s orbit was notable: It came less than 150,000 miles (240,000 km) from Earth, closer than the orbit of theContinue reading "Astronomers just deleted an asteroid because it turned out to be Elon Musk’s Tesla Roadster"

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Author(s): Ryan Wilkinson

Noise is typically detrimental to quantum effects, but simulations suggest that it can boost entanglement under certain conditions.

[Physics 18, s5] Published Wed Jan 22, 2025

Author(s): Sachin Rawat

Researchers predict that having extra sets of chromosomes can both speed up and slow down the evolution of an organism, depending on the organism’s “fitness landscape.”

[Physics 18, 14] Published Tue Jan 21, 2025

Author(s): Kohei Kawabata

Three theoretical studies have uncovered novel types of topological order inherent in open quantum systems, enriching our understanding of quantum phases of matter.

[Physics 18, 9] Published Tue Jan 21, 2025

Author(s): Michael Schirber

Powerful shock waves around magnetized neutron stars may be the source of mysterious radio bursts that are observed across the sky.

[Physics 18, s13] Published Tue Jan 21, 2025

In this episode, Dave Eicher invites you to go out and watch a close pairing of two naked-eye planets: Venus and Saturn. The two will be in the southwestern evening sky, and will be closest during the week of January 19. Each night, brilliant Venus and much less bright (but still easy to see) Saturn will be a bit more than 3Continue reading "Venus meets Saturn: This Week in Astronomy with Dave Eicher"

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Do the periods of comets decrease because they lose mass every time they get near the Sun? Robert BaileyConover, Wisconsin Great question! Assuming you’re referring specifically to the orbital period — in other words, how long comets take to make one revolution around the Sun, or a cometary “year” — according to basic physics, the periodContinue reading "Does a comet’s period change because it loses mass every time it nears the Sun?"

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Chris Schur, taken from Payson, Arizona Comet C/2024 G3 (ATLAS) lies above a mountain ridge in this shot taken before sunrise on Jan. 11, with particulate matter from forest fires giving the sky a reddish hue. The imager used a 3.2-inch refractor and a one-shot color camera to take a 0.1-second exposure.

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 در حدود ۱۳ میلیارد سال پیش، کهکشان‌هایی در جهان وجود داشتند که هنوز از نظر ساختار به کهکشان راه شیری شباهت پیدا نکرده‌بودند. اما چگونه می‌توان از راز این کهکشان‌های باستانی پرده برداشت؟ سرعت شکل‌گیری ستارگان در این کهکشان‌ها تا چه اندازه بوده‌است و چه مسیر تکاملی‌ای را  طی کرده‌اند؟

نور این کهکشان‌ها، پس از سفری طولانی و بی‌نظیر به ما رسیده‌است. در این مسیر، غبار کیهانی^۱، متشکل از ذرات بسیار ریز کربن و سیلیکات، نور را پراکنده^۲ می‌کند و باعث کاهش شدت آن می‌شود. این موضوعی‌ست که مطالعه‌ی کهکشان‌های اولیه را دشوارتر می‌کند. غبار کیهانی علاوه بر جذب کردن نور آن را تغییر هم می‌دهد. برای مثال، نور فرابنفش^۳، بیش‌تر از طول‌موج‌های بلندتر پراکنده می‌شود. این ویژگی باعث می‌شود که کهکشان‌ها قرمزتر و کم‌نورتر از چیزی که هستند به نظر برسند. تصویری جدید از ستون‌های آفرینش^۴، توسط تلسکوپ فضایی جیمز وب، این تغییرات را به وضوح نشان می‌دهد (شکل ۱).

شکل ۱: تلسکوپ فضایی هابل ستون‌های آفرینش را در سال ۱۹۹۵ رصد کرد. در سال ۲۰۱۴، هابل این صحنه را دوباره بازبینی کرد و تصویری واضح‌تر و گسترده‌تر در نور مرئی ارائه داد (سمت چپ). همان تصویر از دید تلسکوپ فضایی جیمز وب (سمت راست).

برای درک بهتر این تغییرات و اصلاح این اعوجاجات نوری، اخترشناسان از ابزارهایی به نام منحنی‌های جذبی غبار^۵ استفاده می‌کنند. این منحنی‌ها تاثیر غبار بر روی نور در طول‌موج‌های مختلف را نشان می‌دهد؛ یعنی چه مقدار از نور در هر طول‌موج پراکنده یا جذب می‌شود. برای مثال، منحنی غبار کهکشان راه شیری دارای برآمدگی خاصی در طول‌ موج ۲۱۷۵ آنگستروم است که ناشی از ذرات ریز کربنی در غبار است. از سوی دیگر، این برآمدگی در منحنی غبار ابر ماژلانی کوچک ^۶ وجود ندارد و در طول‌ موج فرابنفش، شیب بیش‌تری نشان می‌دهد. این تفاوت‌ها، تصادفی نیستند و اطلاعات ارزشمندی درباره ترکیب و توزیع ذرات غبار در کهکشان‌های مختلف به ما می‌دهند.

اما نکته‌ی مهم این است که بیش‌تر منحنی‌های غباری که در اختیار داریم، برای کهکشان‌های نزدیک‌تر مانند راه شیری یا ابر ماژلانی کوچک طراحی شده‌اند. آیا همین منطق و منحنی‌های جذبی برای کهکشان‌هایی که میلیاردها سال پیش وجود داشته‌اند نیز صادق است؟

این پرسش رایان سندرز و تیم او را بر آن داشت که کهکشان GOODSN-17940 را مورد مطالعه قراردهند، کهکشانی ستاره‌فشان^۷ که در انتقال به سرخ  ۴/۴۱ قرار دارد. این کهکشان که تنها ۱/۳۶ میلیارد سال پس از مهبانگ ^۸ وجود داشته، فرصتی بی‌نظیر برای مطالعه‌ی رفتار غبار در گذشته‌ی دور را فراهم می‌کند.

این تیم با استفاده از ابزار طیف‌سنجی فروسرخ نزدیک تلسکوپ فضایی جیمز وب، ۱۱ خط نشری هیدروژن ^۹ از Hα تا H12 را بررسی کردند. این خطوط مانند فانوس‌های دریایی‌ عمل می‌کنند؛ شدت نور آن‌ها نشان می‌دهد که چه مقدار نور در هر طول‌ موج توسط غبار جذب شده‌است. با مقایسه‌ی روشنایی مشاهده‌شده‌ از این خطوط، آن‌ها توانستند منحنی جذبی دقیقی برای کهکشان GOODSN-17940 ترسیم کنند.

شکل ۲: طیف کهکشان GOODSN-17940 ، که خطوط بالمر هیدروژن را نشان می‌دهد. این خطوط طیفی به برآورد شرایط غبار و یونش کهکشان کمک می‌کنند.

منحنی جذبی رصد شده از GOODSN-17940 متفاوت از آن‌چه انتظار می‌رفت ظاهر شده‌است. در ناحیه‌ی فروسرخ^۱۱، این منحنی شیب بسیار بیش‌تری نسبت به منحنی‌های راه شیری یا ابر ماژلانی کوچک دارد. این موضوع احتمالاً به دلیل کوچک‌تر بودن یا توزیع متفاوت ذرات غبار در این کهکشان است. اما در قسمت فرابنفش طیف، این منحنی مسطح‌تر است و جذب کم‌تری نسبت به مدل‌های کلاسیک نشان می‌دهد. همچنین هیچ‌گونه برآمدگی‌ در ۲۱۷۵ آنگستروم دیده نمی‌شود. این یافته‌ها نشان می‌دهد که غبار این کهکشان به دلیل سن بسیار کم جمعیت ستاره‌ای و محیط فعال ستاره‌زا در آن، ویژگی‌های منحصر به فردی دارد. شکل ۳ این نتایج را نشان می‌دهد. محور عمودی بیانگر این است که نور در هر طول‌موج، چند برابر بیش‌تر از مقدار آن در طول‌موج ۹۵۵۰ آنگستروم توسط غبار جذب یا پراکنده می‌شود. به عنوان مثال، مقدار عددی ۲ در این نمودار به این معنی است که نور در آن طول‌ موج دو برابر بیش‌تر از نور در طول‌موج ۹۵۵۰ آنگستروم تضعیف شده‌است.

اما اهمیت این منحنی جذبی جدید در چیست؟ این منحنی در تخمین پارامترهای مهمی چون نرخ شکل‌گیری ستارگان^۱۲، نقش کلیدی دارد. به طور مثال اگر از منحنی غبار کهکشان راه شیری برای کهکشانی مانند GOODSN-17940 استفاده کنید، نرخ شکل‌گیری ستارگان را تا ۵۰٪ کم‌تر برآورد خواهید کرد! این اشتباه، می‌تواند درک ما از ساختار و تحول کهکشان‌ها را به طور کلی تغییر دهد.

تلسکوپ فضایی جیمز وب، با قابلیت‌های خود، به تیم سندرز این امکان را داد که این کهکشان دوردست را مطالعه کرده و بتوانند پیچیدگی غبار را در زمانی حدود ۱۰٪ از عمر کنونی جهان، بررسی کنند. این یافته‌ها به ما کمک می‌کند تا جهان اولیه را با دقتی بی‌سابقه مطالعه کنیم و به درک بهتری از تکامل کهکشان‌ها برسیم.

شکل ۳: منحنی جذبی غبار کهکشان GOODSN-17940 (خط قرمز پیوسته) در انتقال به سرخ (z=4.41)، که در این مطالعه به دست آمده‌است. این منحنی با منحنی‌های شناخته‌شده‌ای چون منحنی جذبی غبار کهکشان راه شیری ( خط سبز خط‌چین)، ابر ماژلانی کوچک ( خط آبی کمرنگ نقطه‌چین)، و یا مدل‌های Calzetti (خط آبی نقطه-خط) و Reddy در انتقال به سرخ حدود ۲ (z∼۲: خط بنفش پیوسته) مقایسه شده است. منحنی این کهکشان در ناحیه‌ی فروسرخ نزدیک دارای شیب‌ بیش‌تر و در ناحیه‌ی فرابنفش مسطح‌تر از سایر نمودارها است، که این نشان‌دهنده‌ی ویژگی‌ منحصربه‌فرد غبار در این کهکشان است.

The jets of a supermassive black hole are one of the cosmos’ greatest spectacles — and also one of its greatest mysteries. These beams of ionized matter burst forth from the cores of galaxies at speeds approaching that of light. How those black holes harness and focus that energy remains hotly contested. In recent years,Continue reading "Unusual spiral quasar seen dancing with a companion"

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Losing the Block 2 Starship on its debut flight was not the optimal outcome. But SpaceX still managed to make significant progress on Flight 7. In October, SpaceX made history by snaring the Super Heavy booster from the sky using a pair of metal chopstick arms attached to a tower on the launch pad, which the companyContinue reading "SpaceX Starship Flight 7 explodes midair, but Super Heavy booster catch successful"

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If there is a leader in the aerospace industry, SpaceX is it. The company’s Crew Dragon and Cargo Dragon spacecrafts are the current go-to vehicles to deliver astronauts and supplies to the International Space Station. NASA contracts awarded to SpaceX through 2030 alone are worth nearly US$5 billion and include research and development for theContinue reading "The Starbase rocket testing facility is permanently changing the landscape of southern Texas"

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Chirag Upreti, taken from the Bronx, New York City Mars is seen just before dipping behind the Moon during its occultation Jan. 13. The photographer used a Sony mirrorless camera and 600mm lens with a x2 teleconverter.

The post Be right back appeared first on Astronomy Magazine.

Author(s): Gerald Holton

The experiment provided further proof of the reality of photons, yet Millikan didn’t accept their existence until later in his career.

[Physics 18, 12] Published Fri Jan 17, 2025

Author(s): Michael Schirber

Measurements of grains flowing down an inclined plane have uncovered general principles that may help researchers model rockslides and other granular flows.

[Physics 18, 13] Published Fri Jan 17, 2025

Star-forming galaxies, including ours, are rich in elements — and secrets. Stars come to life fastest in the early histories of such galaxies, but this process doesn’t last at such a high rate forever. The star-formation rate (SFR) eventually slows.  Thanks to a recent study published Dec. 27, 2024, in The Astrophysical Journal Letters, weContinue reading "Galactic ‘conveyor belt’ circulates elements like carbon in and out of galaxies"

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Friday, January 17Although Jupiter and Mars have been dominating the eastern sky, there’s more here to view than just planets. Already 50° high an hour after sunset, the bright, magnitude 0.1 star Capella stands high above Mars and to Jupiter’s upper left. This is the alpha star of the constellation Auriga, which sits directly aboveContinue reading "The Sky This Week from January 17 to 24: A conjunction of Venus and Saturn"

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Like the Sun shining through the clouds in the early morning, a bright star within the star-forming nebula N79 appears to burst forth through a web of cooler gas and dust in this image taken by the James Webb Space Telescope (JWST). Located in the Large Magellanic Cloud (LMC), a satellite of our Milky WayContinue reading "A young star-forming region shines bright for JWST "

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Just past 2 a.m. Eastern time on Jan. 16, 2025, a new rocket blasted off from the Cape Canaveral Space Force Station in Florida. By reaching orbit, Blue Origin’s New Glenn rocket launch has marked a milestone for a commercial space company that has big ambitions. As a space policy expert, I see New Glenn’sContinue reading "Blue Origin has successfully launched its New Glenn rocket to orbit"

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Author(s): Katherine Wright

Researchers predict the existence of a class of particles that behave differently from those already known.

[Physics 18, 11] Published Thu Jan 16, 2025

Author(s): Marric Stephens

Researchers have built an optical clock using an array of trapped ions—an architecture that can be scaled up to boost the clock’s precision.

[Physics 18, s7] Published Thu Jan 16, 2025

Author(s): Katherine Wright

Researchers find that two types of biological magnetic sensor can sense fields close to the quantum limit, a finding that could guide the design of lab-made devices.

[Physics 18, s8] Published Thu Jan 16, 2025