escape velocity - 2026 ACF Regionals

Question

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>

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Summary


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

Data


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