Publications of the Astronomical Society of Australia

Research Article

K 1-6: An Asymmetric Planetary Nebula with a Binary Central Star

David J. Frewa1 c1, Jeff Stangera2, Michael Fitzgeralda1, Quentin Parkera1a3, Lena Danaiaa4, David McKinnona4, Martín A. Guerreroa5 p1, John Hedberga6, Robert Hollowa7, Yvonne Ana2, Shu Han Bora2, Isabel Colmana2, Claire Graham-Whitea2, Qing Wen Lia2, Juliette Maia2, Katerina Papadakisa2, Julia Picone-Murraya2, Melanie Vo Hoanga2 and Vivian Yeana2

a1 Department of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109, Australia

a2 Sydney Girls High School, Anzac Parade, Surry Hills, NSW 2010, Australia

a3 Australian Astronomical Observatory, PO Box 296, Epping, NSW 1710, Australia

a4 School of Teacher Education, Charles Sturt University, Bathurst, NSW 2795, Australia

a5 Instituto de Astrofísica de Andalucía, CSIC, c/Camino Bajo de Huétor 50, E-18008 Granada, Spain

a6 Department of Education, Macquarie University, North Ryde, NSW 2109, Australia

a7 CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia


We present new imaging data and archival multiwavelength observations of the little-studied emission nebula K 1-6 and its central star. Narrow-band images inHα (+[N II]) and [O III] taken with the Faulkes Telescope North reveal a stratified, asymmetric, elliptical nebula surrounding a central star which has the colours of a late G or early K-type subgiant or giant. GALEX ultraviolet images reveal a very hot subdwarf or white dwarf coincident in position with this star. The cooler, optically dominant star is strongly variable with a period of 21.312± 0.008 days, and is possibly a high-amplitude member of the RS CVn class, although an FK Com classification is also possible. Archival ROSAT data provide good evidence that the cool star has an active corona. We conclude that K 1-6 is most likely an old bona fide planetary nebula at a distance of ∼1.0 kpc, interacting with the interstellar medium, and containing a binary or ternary central star. The observations and data analyses reported in this paper were conducted in conjunction with Year 11 high school students as part of an Australian Research Council Linkage Grant science education project, denoted Space To Grow, conducted jointly by professional astronomers, educational researchers, teachers, and high-school students.

(Received May 18 2010)

(Accepted September 22 2010)


  • stars: AGB and post-AGB;
  • binaries: general;
  • planetary nebulae: general;
  • planetary nebulae: individual: K 1-6


c1 Corresponding author. Email:

p1 Present address: Macquarie University, North Ryde, NSW 2109, Australia