ETA CARINAE A

꧁(ㅎ.ㅎ)꧂

[ETA CARINAE A @ETACARINAEA_]

❓❓❓❔❔❔

[NASA Astronomy Picture of the Day @apod]

Why are Saturn’s poles geometric? Saturn’s North Pole has been known to be surrounded by a hexagonal (6 sides) cloud since discovery in 1987 in data taken by NASA’s Voyager spacecrafts, which quickly flew past the ringed world in the early 1980s. Now, recent observations of Saturn by the Hubble Space Telescope reveal a slightly different geometric cloud pattern around the South Pole: a decagon (10 sides). The geometric boundaries are possibly caused by waves when the fast-moving gas away from the poles interacts with slower-moving gas closer to the poles. In the featured image composite by the Hubble taken last year, the South Pole of Saturn is marked by an X and surrounded by bands of circulating clouds. The decagon appears most prominent in the dark inner regions. The northern hexagon has proven stable for over 40 years, while the stability of the southern decagon will surely remain a topic of research.

Image Credit: NASA, ESA, STScI, HST; A. Sánchez-Lavega (UPV), A. Simon (NASA-GSFC), M. Wong (UC Berkeley); Processing: A. Pagan (STScI)

[sorae 宇宙へのポータルサイト @sorae_jp]

冥王星の衛星「ニクス」の予測できない自転【今日の宇宙画像】
https://t.co/uwMzjqTNUc

冥王星には現在までに5つの衛星が確認されており、ニクスは冥王星に近い順で3番目を公転しています。今回は、どちらを向くか長期的に予測するのが難しい、ニクスの不規則な自転を紹介します

[NASA Astronomy Picture of the Day @apod]

Is this star winking at us?

The central object in today’s animation is not one but two stars. XZ Andromedae, indicated by the bold lines, is an Algol-type eclipsing binary with a nearly edge-on orbit from Earth’s perspective.

The bottom light curve shows the amount of light from the system dim and brighten as the cooler star eclipses its hotter, brighter companion. Analysis of several XZ Andromedae light curves indicates there may be two other stars orbiting the system.

This particular light curve was created with Citizen Astronomy, an open-source software for differential photometry.

The software takes the difference in brightness between a target and comparison star and traces its behavior over time.

This technique reduces most variations from the instrument and Earth’s atmosphere. In addition to eclipsing binaries, this analysis is useful for studying transiting exoplanets, accreting black holes, supernovae, and many more time-varying astronomical phenomena. Astrophotographers: try it out on your own data!

Video Credit: Ogetay Kayali (MTU, Starfront Observatories)
Text: Keighley Rockcliffe (NASA GSFC, UMBC CSST, CRESST II)

[Corey S. Powell @coreyspowell]

Gas + gravity + time leads to amazing results.

Look at this peculiar galaxy pair, NGC 7253. Gravity caused a couple hundred billion balls of hydrogen to light up as stars, held together in two great swarms that then collided, scattered & reassembled.

https://t.co/aNtzshyIAp

[ToughSF @ToughSf]

Eris is actually 25.7% heavier than Pluto.

It has a shiny white surface, while its moon Dysnomia, a quarter of its size, is very dark with an albedo of just 0.05.

This strange pair orbits between 38.1 and 97.49 AU from the Sun.

[ALMA Observatory📡 @almaobs]

📡 “Betelgeuse's atmosphere is becoming spotty and asymmetric—and a nearby companion could be shaping the pattern” by @physorg_com

https://t.co/W41sXpho0N

[天文学者 阿部新助 Dr. Avell @AvellSky]

【土星の南極に十角形：発見したのはアマチュア】
今週NASAが公開したハッブル新画像で、土星南極を取り巻く十角形の雲パターン「Decagon（デカゴン）」が確定。9月2日付 Science Advances に論文掲載されました。
注目すべきは発見の経路です。土星の南極は傾きの関係で2012〜2023年はほぼ観測不能。2024年に幾何条件が好転しはじめると、Trevor Barry（オーストラリア）と Jean-Paul Oger（フランス）のアマチュア撮像に淡い波状構造が写り込みました。2025年夏、Oger が自身の画像を南極中心のマップに合成したところ、十本の辺が明瞭に浮上。これを受けてハッブルによる追観測が行われ、両名は論文の共著者となっています。

■ 諸元 南緯60°、各辺 約17,000 km。ボイジャーが北極で発見した六角形ジェット気流に対し、径はおよそ2倍、緯度も極から離れているため、地球からの見かけの条件が良い。

■ 六角形との違い 北極の六角形は数十年にわたり安定持続している構造ですが、Decagon は成立からまだ数年程度の可能性があり、現在も強化が進行中とみられます。極域ジェットの立ち上がりを同時代で追跡できる、稀なケースです。

■ 観測条件 南極側の傾きは2032年に向けて年々改善します。口径14〜16インチ級＋赤またはIRフィルタで、波打つ縁の検出が狙える。ベストタイミングは10月4日の衝前後。

https://t.co/nUZm6KigwQ

#土星 #Saturn #Decagon #ハッブル宇宙望遠鏡 #惑星観測 #天文学

[NASA Goddard @NASAGoddard]

Star Formation Winding Down 🌌

The Andromeda galaxy shines with stars, but star formation has been declining for the past 500 million years. Using @nasahubble data, scientists measured about 200 million stars to learn about the galaxy’s past activity.

https://t.co/61tztN2J8s

[Epic Maps 🗺️ @theepicmap]

This is How Himalayan Belt form

[Prof. Abel Méndez 🔭 🔬 @ProfAbelMendez]

This animation shows the same star field photographed more than 100 years apart, in 1889 and 1991. Somewhere within the two green boxes, among thousands of stars, lies the source of the Wow! Signal. #AreciboWow

[Latest in space @latestinspace]

NEWS 🚨: NASA’s Roman Space Telescope is ready for liftoff tomorrow at 7:26 a.m. EDT

It will hunt for new exoplanets with a field of view 100 times larger than Hubble’s

[World and Science @WorldAndScience]

Incredible: A Hubble capture of the overlapping spiral galaxies SDSS J115331 and LEDA 2073461, more than a billion light-years away!

(Credit: ESA/Hubble & NASA, W. Keel)

[Massimo @Rainmaker1973]

If the sun disappeared, Earth would continue orbiting for 8 minutes

[sorae 宇宙へのポータルサイト @sorae_jp]

NASAの天文衛星「パンドラ」が科学観測を開始　特定の太陽系外惑星を集中観測へ
https://t.co/d2YtqH3x6V

パンドラは低コスト・短期開発を掲げるNASAの「天体物理学パイオニアプログラム」のもとで開発された最初の衛星で、2026年1月に打ち上げられました

太陽系外惑星の大気組成を調べるために、1年間の主要ミッション期間中に少なくとも20個の太陽系外惑星とその主星を集中的に観測する予定です

[Xavi Bros @Xavi_Bros]

Mimas is a satellite of Saturn with a diameter of 396 km. Its low density, 1.15 g/cm3, indicates that it’s composed of water ice with a small amount of rock and -may be- a liquid ocean under its surface. It’s heavily cratered: Herschel is a crater of 139 km across.
Image: Cassini

[Corey S. Powell @coreyspowell]

Amazing: Evidence of flowing liquid on the surface of Pluto. Pluto!

The fluid is probably liquid nitrogen. In every environment, it seems, some elements or compounds behave in dynamic ways, producing active geology from Mercury to Pluto (and beyond?).

https://t.co/4lyW8hsHKR

[NSFVoyager2 @NSFVoyager2]

OTD in 2012, sister Voyager 1 made her final transition from the region dominated by our Sun's solar wind into the region dominated by the other stars' cumulative winds: 'interstellar space.' For the first time, we were measuring particles mainly from other stars.

The measurements are from the LECP instrument, and the oscillations in late July and August show the buffeting nature of the boundary as it billows out from the Sun and then is pushed back by interstellar pressure, with the boundary moving back and forth over Voyager 1 several times. The August 25, 2012 transition occurred at a distance of 16H:51M light-time from the Sun, or about 121.6 AU.

Voyager 2 encountered this boundary in 2018 from early November to early December, but the boundary was smoother and closer in: from 16H30M to 16H32M, or 119.0 to 119.3 AU. Both crossings occurred during solar sunspot cycle 24, with the V2 crossing possibly occurring at a quieter time.

[Corey S. Powell @coreyspowell]

The historic first Earthrise photo from the Moon was received 60 years ago today. It was shot on film, developed onboard the Lunar Orbiter 1 spacecraft, scanned, transmitted home...and then meticulously restored decades later.

https://t.co/0Vinhsc02u

[ETA CARINAE A @ETACARINAEA_]

B e t e l g e u s e

[NASA History Office @NASAhistory]

At a meeting of the International Astronomical Union 20 years ago today, astronomers vote on a definition of a "planet." The new criteria:

🌘 Must orbit its host star
🌓 Must be mostly round
🌒 Must be massive enough to clear away other objects of similar size in its orbit

Pluto fails on the third condition and becomes a dwarf planet.