銀河系居然是彎的!大綱

Astronomers have created the most precise map to date of the Milky Way by tracking thousands of big pulsating stars spread throughout the galaxy, demonstrating that its disk of myriad stars is not flat but dramatically warped and twisted in shape.
天文學家通過追蹤遍佈銀河系的數千顆大的脈動變星，繪製出了迄今爲止最精確的銀河系地圖。從地圖上看，由無數恆星組成的星系盤並非扁平，而很明顯是彎曲的、扭曲的。

The researchers on Thursday unveiled a three-dimensional map of the Milky Way - home to more than 100 billion stars including our sun - providing a comprehensive chart of its structure: a stellar disk comprised of four major spiral arms and a bar-shaped core region.
研究人員於上週四公佈了一張銀河系的三維地圖，其中包括太陽在內共有1000多億顆恆星。這張地圖全面展示了銀河系結構：由四個大的螺旋型枝節和一個條狀的核心區域組成的星系盤。

'For the first time, our whole galaxy - from edge to edge of the disk - was mapped using real, precise distances,' said University of Warsaw astronomer Andrzej Udalski, co-author of the study published in the journal Science.
研究報告的作者之一、華沙大學天文學家安德烈·烏達爾斯基說：“從星系盤的一端到另一端，我們第一次使用真實、精確的距離繪製了整個銀河系的地圖。”研究報告發表在《科學》雜誌上。

Until now, the understanding of the galaxy's shape had been based upon indirect measurements of celestial landmarks within the Milky Way and inferences from structures observed in other galaxies populating the universe.
到目前爲止，人類對星系形狀的理解是基於對銀河系內天體標誌的間接測量，以及對宇宙中其他星系結構的推斷。

The new map was formulated using precise measurements of the distance from the sun to 2,400 stars called 'Cepheid variables' scattered throughout the galaxy.
這幅新地圖是通過精確測量散佈在銀河系中的2400顆“造父變星”與太陽之間的距離而繪製的。

'Cepheids are ideal to study the Milky Way for several reasons,' added University of Warsaw astronomer and study co-author Dorota Skowron.
“造父變星是研究銀河系的理想選擇，原因有很多，”華沙大學天文學家、研究報告的合著者多洛塔·斯考倫補充道。

'Cepheid variables are bright supergiant stars and they are 100 to 10,000 times more luminous than the sun, so we can detect them on the outskirts of our galaxy. They are relatively young - younger than 400 million years - so we can find them near their birthplaces.'
“造父變星是明亮的超巨星，其亮度是太陽的100到一萬倍，所以我們可以在銀河系的外圍探測到它們。它們形成的時間相對較短，不到4億年，所以可以在其發源地附近找到它們。”

The astronomers tracked the Cepheids using the Warsaw Telescope located in the Chilean Andes.
天文學家使用位於智利安第斯山脈的華沙望遠鏡追蹤造父變星。

These stars pulsate at regular intervals and can be seen through the galaxy's immense clouds of interstellar dust that can make dimmer stellar bodies hard to spot.
這些恆星有規律地發生脈動，可以透過星系中巨大的星際塵埃雲看到，這些塵埃雲會使較暗的恆星體很難被發現。

The map showed that the galaxy's disk, far from flat, is significantly warped and varies in thickness from place to place, with increasing thickness measured further from the galactic center.
這張地圖顯示，銀河系的星系盤遠非平面狀，而明顯是彎曲的，且各處厚度不一，距離星系中心越遠處越厚。

The disk boasts a diameter of about 14,000 light years. Each light year is about 6 trillion miles (9 trillion km).
銀河系星系盤的直徑約爲1.4萬光年。每光年大約有6萬億英里（9萬億公里）。

The Milky Way began to form relatively soon after the Big Bang explosion that marked the beginning of the universe some 13.8 billion years ago.
銀河系是在大約138億年前宇宙大爆炸後不久開始形成的。宇宙大爆炸標誌着宇宙的起源。

The sun, located roughly 26,000 light years from the supermassive black hole residing at the center of the galaxy, formed about 4.5 billion years ago.
太陽形成於大約45億年前，距離位於星系中心的超大質量黑洞約2.6萬光年。