Question

1. scientists have estimated the numbers of stars that have been formed since the universe began. the number of stars that are formed in each time period is called the star formation rate.

the graph shows the results of these estimates.

(a). describe the trends in the results.
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(b) describe what is meant by the term stellar nursery.
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Explanation:

Part (a)

Step 1: Analyze early period (0 - ~6000 million years)

From 0 to around 6000 million years (age of universe), the star formation rate (y - axis) increases. The graph rises steeply at first (0 - 2000 Myr) then more gradually until a peak around 6000 Myr.

Step 2: Analyze peak to present (6000 Myr - present)

After the peak (around 6000 Myr), the star formation rate decreases. It continues to decline from the peak until the present day (14000 Myr), with the Sun forming around 10000 Myr during this declining phase.

A stellar nursery is a region (e.g., a dense cloud of gas and dust, like a molecular cloud) where stars are born. Gravitational collapse of gas/dust within these regions leads to the formation of new stars.

Answer:

From the start of the universe (0 million years) to around 6000 million years, the star formation rate increases (rising steeply initially then more gradually to a peak). After ~6000 million years (including when the Sun forms ~10000 million years ago) until the present day, the star formation rate decreases (continuously falling).

Part (b)