escape velocity - 2026 ACF Regionals

Packet I: Bonus 1

Answer the following about hypervelocity stars, for 10 points each.

[10e] Hypervelocity stars are typically defined as exceeding this velocity, the velocity required for an object to overcome a central body’s gravity.

ANSWER: escape velocity

[10h] Hypervelocity stars are generated from the three-body interaction between a supermassive black hole and a binary system in a mechanism named for this astronomer. He names the hypothesized circumstellar disk that spans the interior of the Oort cloud.

ANSWER: Jack G. Hills [or Hills cloud; reject “Hill” or “Hill sphere”]

[10m] Most hypervelocity stars were discovered by this now-retired ESA telescope, which was the successor to the Hipparcos mission. Its third data release includes data on nearly 2 billion stars, making it the most comprehensive survey of the Milky Way.

ANSWER: Gaia

<GC, Other Science> | Packet I - McGill B, UCLA A, Michigan B, Georgia Tech C, Southampton B

Heard	PPB	E %	M %	H %
63	10.79	95%	11%	2%

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Conversion

Team	Opponent	Part 1	Part 2	Part 3	Total	Parts
Alabama A	Tennessee B	10	0	0	10	E
Berkeley A	Berkeley D	10	0	0	10	E
Berkeley B	Stanford B	10	0	10	20	EM
Binghamton A	Cornell C	10	0	0	10	E
Brandeis A	MIT	10	0	10	20	EM
Brandeis B	Bowdoin A	10	10	0	20	EH
Bristol	LSE	10	0	0	10	E
Brown	Bowdoin B	10	0	0	10	E
Bruin	WashU B	10	0	0	10	E
Cambridge B	Imperial A	10	0	10	20	EM
Central Florida A	Florida C	10	0	0	10	E
Central Florida C	Central Florida B	10	0	0	10	E
Chicago B	Notre Dame A	10	0	0	10	E
Chicago D	Purdue B	10	0	0	10	E
Chicago E	Notre Dame B	10	0	0	10	E
Claremont	Iowa State	10	0	0	10	E
Columbia A	Maryland A	10	0	0	10	E
Columbia B	NYU A	10	0	0	10	E
Cornell A	Penn State	10	0	0	10	E
Cornell B	RIT	10	0	0	10	E
Dartmouth A	Harvard A	10	0	10	20	EM
Dartmouth B	Southern Connecticut State	10	0	0	10	E
Durham	City St. George's	10	0	0	10	E
Edinburgh B	Imperial C	10	0	0	10	E
Florida A	Florida B	10	0	0	10	E
Georgetown	Columbia C	10	0	0	10	E
Georgia Tech A	Minnesota A	10	0	0	10	E
Georgia Tech B	Mississipi State	10	0	0	10	E
Illinois A	Indiana A	10	0	0	10	E
Illinois B	Chicago C	10	0	0	10	E
Indiana B	Northwestern D	0	0	0	0
James Madison A	Liberty C	0	0	0	0
James Madison B	Liberty B	0	0	0	0
John Jay	Catholic	10	0	0	10	E
Johns Hopkins A	NYU B	10	0	10	20	EM
Louisville A	Georgia Tech D	10	0	0	10	E
Louisville B	Kentucky	10	0	10	20	EM
Maryland B	Vassar	10	0	0	10	E
McGill A	UBC B	10	0	0	10	E
Missouri A	Washington A	10	0	0	10	E
Murray State A	Texas A	10	0	0	10	E
NC State A	North Carolina C	10	0	0	10	E
NYU C	Johns Hopkins B	10	0	0	10	E
North Carolina B	NC State B	10	0	0	10	E
Northwestern B	Illinois C	10	0	0	10	E
Northwestern C	Indiana C	10	0	0	10	E
Oxford A	Cambridge C	10	0	0	10	E
Oxford B	UCL	10	0	0	10	E
Purdue A	Chicago A	10	0	0	10	E
Rochester	Binghamton B	10	0	0	10	E
Rutgers A	Rutgers B	10	0	0	10	E
South Carolina A	Liberty A	10	0	0	10	E
South Carolina B	VCU	10	0	0	10	E
Stanford A	Berkeley C	10	0	0	10	E
Swarthmore	Maryland C	10	0	0	10	E
Tennessee A	Sewanee	10	0	0	10	E
Texas A&M A	Texas B	10	0	0	10	E
Virginia Tech A	North Carolina A	10	0	0	10	E
Virginia Tech B	Virginia	10	0	0	10	E
WashU A	Vanderbilt B	10	0	10	20	EM
Washington B	Carleton College	10	0	0	10	E
William and Mary	Duke	10	0	0	10	E
Yale	Harvard B	10	0	0	10	E

Summary

Tournament	Edition	Match	Heard	PPB	E %	M %	H %
California (North)	Main Site	✓	3	13.33	100%	33%	0%
Canada	Main Site	✓	1	10.00	100%	0%	0%
Florida	Main Site	✓	3	10.00	100%	0%	0%
Lower Mid-Atlantic	Main Site	✓	9	7.78	78%	0%	0%
Midwest	Main Site	✓	9	8.89	89%	0%	0%
Northeast	Main Site	✓	6	15.00	100%	33%	17%
Overflow	Main Site	✓	4	10.00	100%	0%	0%
South Central	Main Site	✓	2	10.00	100%	0%	0%
Southeast	Main Site	✓	7	12.86	100%	29%	0%
UK	Main Site	✓	6	11.67	100%	17%	0%
Upper Mid-Atlantic	Main Site	✓	9	11.11	100%	11%	0%
Upstate NY	Main Site	✓	4	10.00	100%	0%	0%