OG2020每日閱讀訓練練習D14

Pistachio_lin

Hi 大家好，閱讀打卡訓練第14天,

Materials/sources: OG2020

Passage:

    In addition to conventional galaxies, the universe contains very dim galaxies that until recently went unnoticed by astronomers. Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger. Because these galaxies' mass is spread out over larger areas, they have far fewer stars per unit volume than do conventional galaxies. Apparently these low-surface-brightness galaxies, as they are called, take much longer than conventional galaxies to condense their primordial gas and convert it to stars—that is, they evolve much more slowly.

    These galaxies may constitute an answer to the long-standing puzzle of the missing baryonic mass in the universe. Baryons—subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are. However, the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe than estimates based on galactic luminosity indicate. Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect.

簡化/思路:    

    In addition to conventional galaxies, the universe contains very dim galaxies that until recently went unnoticed by astronomers. (開頭先引入了dim galaxies, 對比的對象, 特色)

    Possibly as numerous as conventional galaxies, these galaxies have the same general shape and even the same approximate number of stars as a common type of conventional galaxy, the spiral, but tend to be much larger. (Possibly <猜測語氣>, 舉出相似與相異處: dim galaxies tend to be much larger)

    Because these galaxies' mass is spread out over larger areas, they have far fewer stars per unit volume than do conventional galaxies. (Because <解釋>, 因為dim galaxies的某個特色)

    Apparently these low-surface-brightness galaxies, as they are called, take much longer than conventional galaxies to condense their primordial gas and convert it to stars—that is, they evolve much more slowly. (又繼續提出一個相異處, 長得慢) -- (天文的文章都很複雜，先在這裡裡先整理一下 ，這一段先說dim galaxies, 說出它與傳統galaxies的差異，總共三點, - 大小, fewer starts per unit volume, evolve much slowy)

    These galaxies may constitute an answer to the long-standing puzzle of the missing baryonic mass in the universe. (介紹dim galaxies可以做為什麼用途)
   
    Baryons —subatomic particles that are generally protons or neutrons—are the source of stellar, and therefore galactic, luminosity, and so their numbers can be estimated based on how luminous galaxies are. (在這個long-standing puzzle下, 先談了baryons; 可以用來預估galaxies的亮度以及原因*Baryons的數量，是按照亮度而估出來的)

     However, the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe than estimates based on galactic luminosity indicate. (但是上面說的方法, 跟現在這一句說: 用helium測出來的數量對不上. 有個*however)

     Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect. (說明, 一直對不上這數字, Astronomer說, 一定會有原因來解釋這個差異, 1) 差額會某天被發現2) 某些galaxies很難被發現<第一段的論述剛好能對上這個第二點>)

段落總結:
第一段: 先介紹一個新發現/現象/事物, 以及這新東西與既有發現之間的差異
第二段: 說明這個新發現或許可以用來解釋長期以來未解之謎。

1. According to the passage, conventional spiral galaxies differ from low-surface-brightness galaxies in which of the following ways?

(A) They have fewer stars than do low-surface brightness galaxies.
(B) They evolve more quickly than low-surfacebrightness galaxies. (第一段處; 比較差異的部分)
(C) They are more diffuse than low-surface brightness galaxies.
(D) They contain less helium than do low-surface brightness galaxies.
(E) They are larger than low-surface-brightness galaxies.


2. It can be inferred from the passage that which of the following is an accurate physical description of typical low-surface-brightness galaxies?

(A) They are large spiral galaxies containing fewer stars than do conventional galaxies.
(B) They are compact but very dim spiral galaxies.
(C) They are diffuse spiral galaxies that occupy a large volume of space. (同第一段處, 差異比較的部分)
(D) They are small, young spiral galaxies that contain a high proportion of primordial gas.
(E) They are large, dense spirals with low luminosity.

3. It can be inferred from the passage that the “longstanding puzzle” refers to which of the following?

(A) The difference between the rate at which conventional galaxies evolve and the rate at which low-surface-brightness galaxies evolve

(B) The discrepancy between estimates of total baryonic mass derived from measuring helium and estimates based on measuring galactic luminosity (第二段的however處說明了這件事)

(C) The inconsistency between the observed amount of helium in the universe and the number of stars in typical low-surface-brightness galaxies

(D) Uncertainties regarding what proportion of baryonic mass is contained in intergalactic space and what proportion in conventional galaxies

(E) Difficulties involved in detecting very distant galaxies and in investigating their luminosity

4. The author implies that low-surface-brightness galaxies could constitute an answer to the puzzle discussed in the second paragraph primarily because

(A) they contain baryonic mass that was not taken into account by researchers using galactic luminosity to estimate the number of baryons in the universe. (定位最後一句. 因為dim galaxies很能被發現, 所以在測量量度的時候沒有發現這些東西的亮度, 就沒有針對這些dim galaxies的亮度去推估baryons)

(B) they, like conventional galaxies that contain many baryons, have evolved from massive, primordial gas clouds

(C) they may contain relatively more helium, and hence more baryons, than do galaxies whose helium content has been studied using spectroscopy

(D) they have recently been discovered to contain more baryonic mass than scientists had thought when low-surface-brightness galaxies were first observed

(E) they contain stars that are significantly more luminous than would have been predicted on the basis of initial studies of luminosity in lowsurface-brightness galaxies

5. The author mentions the fact that baryons are the source of stars' luminosity primarily in order to explain

(A) how astronomers determine that some galaxies contain fewer stars per unit volume than do others
(B) how astronomers are able to calculate the total luminosity of a galaxy (這是很強的干擾項, 第一並沒有說"total" luminosity. 此外, 題目原處說的是 "baryons"的數量是如何得出, 這句話把因果關係倒置了)
(C) why astronomers can use galactic luminosity to estimate baryonic mass (這裡介紹的是原因; 先說明baryos的特色, 後面說因為這特色按照亮度可以推出baryons的數量)
(D) why astronomers' estimates of baryonic mass based on galactic luminosity are more reliable than those based on spectroscopic studies of helium
(E) how astronomers know bright galaxies contain more baryons than do dim galaxies

6. The author of the passage would be most likely to disagree with which of the following statements?

(A) Low-surface-brightness galaxies are more difficult to detect than are conventional galaxies. (最後一句: some large population of galaxies that are difficult to detect.)
(B) Low-surface-brightness galaxies are often spiral in shape. (比較處: as a common type of conventional galaxy, the spira,)
(C) Astronomers have advanced plausible ideas about where missing baryonic mass might be found. (最後一句: Astronomers have long speculated that the missing baryonic mass might eventually be discovered in intergalactic space or as some large population of galaxies that are difficult to detect)
(D) Astronomers have devised a useful way of estimating the total baryonic mass in the universe. (定位: the amount of helium in the universe, as measured by spectroscopy, suggests that there are far more baryons in the universe; 這句話的assumption應該是 total baryons數量可以被測量, 所以當這數量跟用galaxies推估出來的數量有差異的時候, astronomers才會有文末最後一句的結論)
(E) Astronomers have discovered a substantial amount of baryonic mass in intergalactic space. (整段文章沒說)

7. The primary purpose of the passage is to

(A) describe a phenomenon and consider its scientific significance (同大意分析, 先介紹了dim galaxies <一種現象>, 接著說他的重要性 <in terms of answering the long-standing puzzle>)
(B) contrast two phenomena and discuss a puzzling difference between them (前面是對的, 確實有contrast. 但是puzzle並不是存在於conventional galaxies跟dim galaxies之間)
(C) identify a newly discovered phenomenon and explain its origins
(D) compare two classes of objects and discuss the physical properties of each
(E) discuss a discovery and point out its inconsistency with existing theory

以上分析, 還請其他有心得的大大們不吝分享。謝謝。