Anna N. Żytkow (; born 21 February 1947) is a Polish astrophysicist working at the Institute of Astronomy of the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

. Żytkow and

Kip Thorne Kip Stephen Thorne (born June 1, 1940) is an American theoretical physicist known for his contributions in gravitational physics and astrophysics. A longtime friend and colleague of Stephen Hawking and Carl Sagan, he was the Richard P. Fey ...

proposed a model for what is called the

Thorne–Żytkow object A Thorne–Żytkow object (TŻO or TZO), also known as a hybrid star, is a conjectured type of star wherein a red giant or red supergiant contains a neutron star at its core, formed from the collision of the giant with the neutron star. Such ob ...

, which is a star within another star. Żytkow in 2014 was part of the team led by Emily M. Levesque which discovered the first candidate for such an object.

Thorne-Żytkow objects

Working together with

in 1976, Żytkow developed a theoretical model for a new star type, the

(TŻO), which contains either a

neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white ...

or a black hole core at the center of a stellar envelope. The evolution of such a star occurs rarely and only two processes exist that define the structure and evolution of a TŻO. In the first process a collision between a neutron star and a normal star, either dwarf or giant, must occur in order to merge the two into a single object. This occurrence is rare since stars do not usually collide with each other. This could only happen in a dense cluster of stars. The second possible evolution of a larger TŻO can occur when a star expands into a red supergiant and engulfs its companion neutron star. A team led by

Emily Levesque Emily Levesque (born 1984) is an American astronomer and assistant professor in the Department of Astronomy at the University of Washington. She is renowned for her work on massive stars and using these stars to investigate galaxy formation. In ...

(University of Colorado at Boulder) and including Anna Żytkow found the first viable TŻO candidate using the 6.5-meter Magellan Clay Telescope at Las Campanas Observatory in 2014, possibly succeeding in a search for these bizarre stars, one that had already spanned some 40 years worth of effort. Żytkow said upon the discovery: "I am extremely happy that observational confirmation of our theoretical prediction has started to emerge. Since Kip Thorne and I proposed our models of stars with neutron cores, people were not able to disprove our work. If theory is sound, experimental confirmation shows up sooner or later. So it was a matter of identification of a promising group of stars, getting telescope time and proceeding with the project.”

Personal life

Żytkow's career was interrupted by a mountaineering accident that nearly took her life.

Kuiper belt discoveries

In December 1995,

Mike Irwin Mike may refer to: Animals * Mike (cat), cat and guardian of the British Museum * Mike the Headless Chicken, chicken that lived for 18 months after his head had been cut off * Mike (chimpanzee), a chimpanzee featured in several books and document ...

Scott Tremaine Scott Duncan Tremaine (born 1950) is a Canadian-born astrophysicist. He is a fellow of the Royal Society of London, the Royal Society of Canada and the National Academy of Sciences. Tremaine is widely regarded as one of the world's leading as ...

, and Anna N. Żytkow collaborated on the

survey Survey may refer to: Statistics and human research * Statistical survey, a method for collecting quantitative information about items in a population * Survey (human research), including opinion polls Spatial measurement * Surveying, the techniq ...

of two slow-moving objects, which are probable members of the

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

. Żytkow and the group followed Edgeworth (1949) and Kuipers (1951) research, which indicates that protoplanetary disks extend beyond Neptune and that the disk material beyond Neptune had not coalesced into planets. This group of planetesimals is now known as the Kuiper belt. Żytkow and the rest of the group members spent most of their time adjusting the focus of the camera and instruments attached to the

Isaac Newton Telescope The Isaac Newton Telescope or INT is a 2.54 m (100 in) optical telescope run by the Isaac Newton Group of Telescopes at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984. Originally the INT was situated at Her ...

(INT). The group used the

Monte Carlo method Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be determi ...

, which provided multiple simulations in two separate stages. The first stage is the detection rate for images that came from INT as a function of magnitude, which was investigated using artificial images adding to the original frames. The second stage involved examining the detection rate for a series of artificial images from INT that followed the typical slow moving solar system objects (SMO) track. The outcome of this survey was a detection of two new Kuiper belts objects within the area of 0.7 degree sq. to a limiting magnitude mR=23.5.

Publications

* The proper motion of HV2112: a TŻO candidate in the SMC; '' Monthly Notices of the Royal Astronomical Society Letters''; Mar. 2016; Clare C. Worley, Mike J. Irwin, Christopher Tout, Anna N. Żytkow, Morgan Fraser, Robert G. Izzard:

* A Search for Thorne-Zytkow Objects; ''

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

''; January 2014; Emily M. Levesque Philip Massey Anna N. Żytkow Nidia Morrell

* HV2112, a Thorne-Zytkow Object or a Super Asymptotic Giant Branch Star; '' Monthly Notices of the Royal Astronomical Society Letters''; 23 June 2014; Christopher Tout, Anna N. Zytkow, Ross P. Church, Herbert Ho Bun Lau

* Discovery of a Thorne-Zytkow object candidate in the Small Magellanic Cloud; '' Monthly Notices of the Royal Astronomical Society Letters''; September 2014; Emily M. Levesque, Philip Massey, Anna N. Zytkow, Nidia Morrell

* Quasi-stars, giants and the Schönberg–Chandrasekhar (SC) limit; ''

Monthly Notices of the Royal Astronomical Society ''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes letters and papers reporting orig ...

''; January 2012; Warrick H. Ball, Christopher Tout, Anna N. Żytkow

* FY Aquilae and the gamma-ray burst GB 790331; ''

Astrophysical Journal ''The Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and Jame ...

'', part 2, vol. 433, no. 2, p. L81-L84; 12 July 1994; Mike Irwin, Anna N. Zytkow

* A variable star in the vicinity of the soft γ-ray repeater 1806 – 20; ''

'', vol. 263, iss. 1; 1 July 1993; Mike Irwin Anna N. Żytkow

* The structure and evolution of Thorne-Zytkow objects; ''

'', part 1, vol. 386; Feb. 10, 1992;Robert C. Cannon, P. P. Eggleton, A. N. Zytkow, P. Podsiadlowski

* Giant and supergiant stars with degenerate neutron cores; ''

'', Part 1; Chris Eich; Mark E. Zimmermann; Kip S. Thorne; Anna N. Zytkow; 1 November 1989

* Stationary spherical accretion into black holes. I - Equations of structure; ''

'', vol. 194; Feb., 1981; Kip S. Thorne; Richard A. Flammang, Anna N. Zytkow

* Hydrogen shell flashes in a white dwarf with mass accretion; ''

'', Part 1, vol. 222; 1 June 1978; Bohdan Paczynski, Anna N. Zytkow

* Stars with degenerate neutron cores. I - Structure of equilibrium models; ''

'', part 1, vol. 212; Mar. 15, 1977; Kip S. Thorne;, Anna N. Zytkow

* The relativistic equations of stellar structure and evolution. Stars with degenerate neutron cores. 1: Structure of equilibrium models; ''

'', part 1, vol. 212; Mar. 15, 1977; Kip S. Thorne;, Anna N. Zytkow

* Red giants and supergiants with degenerate neutron cores neutron cores. 1: Structure of equilibrium models; ''

'', vol. 199; 1 July 1975; Kip S. Thorne;, Anna N. Zytkow

References

External links

Publications
1947 births Astronomers at the University of Cambridge Discoverers of minor planets Discoveries by Anna N. Żytkow Living people Polish astrophysicists Polish women physicists Women astrophysicists University of Warsaw alumni {{improve categories, date=November 2022