Jump to content

iPTF14hls

Coordinates: Sky map 09h 20m 34.30s, −50° 41′ 46.8″
From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by BatteryIncluded (talk | contribs) at 21:20, 10 November 2017 (→Future observations: an ongoing event, more observations will inform the nature of this.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

iPTF14hls
Example of a supernova
Constellation[[Ursa Major (constellation)|Ursa Major]]
EpochJ2000[1]

iPTF14hls is an unusual supernova star that has erupted continuously for the last three years,[2] and it may have exploded between two[3] and five times since 1954.[4] None of the theories and hypotheses fully explain all aspects of the object.

Observations

Supernova iPTF14hls before and after detection

The star iPTF14hls was discovered in September 2014 by the Intermediate Palomar Transient Factory,[3] and astronomers identified it as an exploding star in January 2015.[4] It was thought then that it was a single supernova event (Type II-P) that would dim in about 100 days, but instead, it continued its eruption for more than 600 days while fluctuating in brightness at least five times. The brightness varied by as much as 50% on an irregular timescale, as if it was exploding over and over again.[4] Also, rather than cooling down as expected, the star maintained a near-constant temperature of about 5,700 °C (5,970 K).[4]

The principal investigator is Iair Arcavi. His international team used the Low Resolution Imaging Spectrometer (LRIS) on the Keck I telescope to obtain the spectrum of the star's host galaxy, and the Deep Imaging and Multi-Object Spectrograph (DEIMOS) on Keck II to obtain high-resolution spectra of the unusual supernova itself.[5]

The host galaxy of iPTF14hls is a star-forming dwarf galaxy, implying low metal content,[1] and the weak iron-line absorption seen in the supernova spectra are consistent with a low metallicity progenitor.[1] The researchers also remark that the debris expansion rate is slower than any other known supernova by a factor of 6, as if exploding in slow-motion.[1] However, relativistic time dilation would cause the spectrum to be red-shifted by the same factor of 6, which is inconsistent with their observations.[1]

Future observations

iPTF14hls is an ongoing event. When it finally becomes a remnant nebula, new clues as to the nature of the progenitor star and the explosion mechanism may be revealed. Arcavi's team plans to continue monitoring the object in other bands of the spectrum in collaboration with additional international telescopes and observatories.[6] These facilities include the Nordic Optical Telescope and NASA's Swift space telescope, that will look for X-ray emission, while the Hubble Space Telescope will begin to image the location beginning in December 2017.[6]

Hypotheses

Current theory predicts that the star would consume all its hydrogen in the first explosion, and depending on the initial size of the star, the remnants of the core should form a neutron star or a black hole, so it is thought that there is a novel unidentified phenomenon happening.[2][3][4] There is no known theory that explains the observation.[7][8] Acording to the researchers, this discovery requires refinement of existing explosion scenarios, or the development of a new scenario, that can: [1]

  1. produce the same spectral signatures as common Type IIP supernovae but with an evolution slowed down by a factor of 6 to 10.
  2. provide energy to prolong the light curve by a factor of ~6 while not introducing narrow-line spectral features or strong radio and x-ray emission indicative of circumstellar material interaction.
  3. produce at least five peaks in the light curve.
  4. decouple the deduced line-forming photosphere from the continuum photosphere.
  5. maintain a photospheric phase with a constant line velocity gradient for over 600 days.

One hypothesis is that it involves burning antimatter in a stellar core,[3] causig the star to become extremely unstable, and undergo repeated bright eruptions over periods of years.[9] Another hypothesis is the pulsational pair-instability supernova, a massive star that may lose about half its mass before a series of violent pulses begins.[2][10] On every pulse, material rushing away from the star can catch up with earlier ejected material, producing bright flashes of light as it collides, simulating an additional explosion (see Supernova impostor). But neither hypothesis can explain the continued presence of hydrogen or the energetics observed.[2][10]

References

  1. ^ a b c d e f Arcavil, I; et al. (2017). "iPTF14hls: A unique long-lived supernova from a rare explosion channel" (PDF). Caltech. Retrieved 9 November 2017. {{cite web}}: Explicit use of et al. in: |author= (help)
  2. ^ a b c d Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star. Iair Arcavi, D. Andrew Howell, Daniel Kasen, Lars Bildsten, Griffin Hosseinzadeh, et al. Nature. 551, 210–213; 9 November 2017.doi:10.1038/nature24030
  3. ^ a b c d This star cheated death, exploding again and again. Lisa Grossman, Science News. 8 November 2017.
  4. ^ a b c d e 'Zombie' star survived going supernova. By Paul Rincon, BBC News. 8 November 2017.
  5. ^ Astronomers Discover A Star That Would Not Die. W. M. Keck Observatory. 8 November 2017.
  6. ^ a b Bizarre 3-Year-Long Supernova Defies Our Understanding of How Stars Die. Harrison Tasoff, Space. 8 November 2017.
  7. ^ What Type of Star Made the One-of-a-kind Supernova iPTF14hls?. Arcavi, Iair. August 2017.
  8. ^ Scientists on new supernova: WTF have we been looking at?. John Timmer, Ars Technica. 8 November 2017.
  9. ^ This Star Went Supernova … And Then Went Supernova Again. Jake Parks, Discovery Magazine. 9 November 2017.
  10. ^ a b 'Zombie star' amazes astronomers by surviving multiple supernovae. Ian Sample, The Guardian. 8 November 2017.


Retrieved from "https://en.wikipedia.org/w/index.php?title=IPTF14hls&oldid=809702801"