Bonus
Stars in these systems have approximately the same age because they formed from the same molecular cloud. For 10 points each:
[10e] Name these systems that differ from stellar associations by being gravitationally bound. The Pleiades (“PLEE-uh-deez”) and Hyades (“HY-uh-deez”) are examples of the “open” type of these systems, which are much younger than “globular” ones.
ANSWER: star clusters [accept globular clusters or open clusters]
[10h] The age of a cluster can be determined by plotting its members on the H–R diagram and fitting one of these curves. One can estimate that fit by comparing these curves’ main-sequence turnoff points to the data.
ANSWER: stellar isochrones (“ICE-uh-krones”)
[10m] Knowing a cluster’s value for this quantity is necessary to determine its age, as increasing either variable shifts isochrones to the right. High values of this quantity differentiate Population I stars from Populations II and III.
ANSWER: metallicity [accept metal content or metal richness; prompt on Z]
<Other Science>
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Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| Arizona State | Georgia State | 10 | 0 | 10 | 20 | EM |
| British Columbia | Yale | 10 | 0 | 10 | 20 | EM |
| Chicago A | UC Berkeley A | 10 | 0 | 10 | 20 | EM |
| Columbia B | Michigan | 10 | 0 | 10 | 20 | EM |
| Florida | Ottawa | 10 | 0 | 10 | 20 | EM |
| Georgia Tech | Virginia Tech | 10 | 0 | 0 | 10 | E |
| Harvard | Toronto C | 10 | 0 | 10 | 20 | EM |
| Illinois A | North Carolina A | 10 | 0 | 10 | 20 | EM |
| Illinois B | Maryland | 10 | 0 | 0 | 10 | E |
| Iowa State | Toronto B | 10 | 0 | 10 | 20 | EM |
| Johns Hopkins | Chicago B | 10 | 0 | 10 | 20 | EM |
| MIT | Cornell A | 10 | 0 | 10 | 20 | EM |
| Minnesota | Texas | 10 | 0 | 10 | 20 | EM |
| NYU | LSE | 10 | 0 | 0 | 10 | E |
| North Carolina B | UCF | 0 | 0 | 0 | 0 | |
| Northwestern | Toronto A | 10 | 0 | 10 | 20 | EM |
| RIT | Vanderbilt | 10 | 0 | 0 | 10 | E |
| Rutgers | Stanford | 10 | 0 | 10 | 20 | EM |
| UC Berkeley B | Penn State | 10 | 0 | 0 | 10 | E |
| Virginia | Ohio State | 10 | 0 | 0 | 10 | E |
| WUSTL A | Columbia A | 10 | 0 | 10 | 20 | EM |
| WUSTL B | Waterloo B | 10 | 0 | 10 | 20 | EM |
| Waterloo A | Indiana | 10 | 0 | 10 | 20 | EM |
| Winona State | Cornell B | 0 | 0 | 0 | 0 |
Summary
| Tournament | Exact Match? | Heard | PPB | Easy % | Medium % | Hard % |
|---|---|---|---|---|---|---|
| 2025 ACF Nationals | Yes | 24 | 15.83 | 92% | 67% | 0% |