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Small, or just invisible?

"Heavy Find: Weighty neutron stars may nile out exotic core" (SN: 1/12/08, p. 20) says that the companion star of the pulsar pulsar, in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and his students at Cambridge Univ.  PSR PSR Pulsar
PSR Poster
PSR Physicians for Social Responsibility
PSR Psychosocial Rehabilitation
PSR Pacific School of Religion
PSR Policy and Survey Research
PSR Project Study Report
PSR Pre-Sentence Report
PSR Pressure-State-Response
PSR Puget Sound Region
 B1516+02B must be "tiny" because it cannot be seen. Isn't it possible that the companion is made of dark matter? Is there a "wobble wobble /wob·ble/ (wob´'l) to move unsteadily or unsurely back and forth or from side to side. See under hypothesis.

" test or other way to discern between a companion that is truly tiny (low mass) and one that is perhaps more massive but not visible? The mass of the companion star seems to bear directly on the conclusion favoring heavy neutron stars.


The companion to PSR B1516+02B is very likely a white dwarf star white dwarf star

Any of a class of small, faint stars representing the end point of the evolution of stars without enough mass to become neutron stars or black holes.
, says Paulo Freire Paulo Freire (Recife, Brazil September 19, 1921 - São Paulo, Brazil May 2, 1997) was a Brazilian educator and is a highly influential theorist of education. Biography  of Arecibo Observatory in Puerto Rico. White dwarfs are faint, and become harder to detect as they grow older and cooler. Few companions to millisecond pulsars have ever been directly detected, but those that have are almost all white dwarfs. Freire adds that dark matter seems to clump at galactic scales, and that he is not aware of any theoretical predictions of clark matter able to form small objects like stars.--RON COWEN
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Title Annotation:LETTERS
Author:McAllister, Maureen; Cowen, Ron
Publication:Science News
Article Type:Letter to the editor
Date:Feb 9, 2008
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