CaltechAUTHORS
Published December 1, 2022 | Version public
Journal Article Metadata-only

Early Results from GLASS-JWST. VIII. An Extremely Magnified Blue Supergiant Star at Redshift 2.65 in the A2744 Cluster Field

Creators

  • 1. ROR icon University of Minnesota
  • 2. ROR icon University of California, Los Angeles
  • 3. ROR icon University of Chinese Academy of Sciences
  • 4. ROR icon National Astronomical Observatories
  • 5. ROR icon Infrared Processing and Analysis Center
  • 6. ROR icon Arizona State University
  • 7. ROR icon University of Ljubljana
  • 8. ROR icon University of California, Davis
  • 9. ROR icon University of Copenhagen
  • 10. ROR icon University of the Basque Country
  • 11. ROR icon Donostia International Physics Center
  • 12. ROR icon Ikerbasque
  • 13. ROR icon Institute of Physics of Cantabria
  • 14. ROR icon University of Arizona
  • 15. ROR icon Ben-Gurion University of the Negev
  • 16. ROR icon University of California, Berkeley
  • 17. ROR icon Astronomical Observatory of Rome
  • 18. ROR icon Tufts University
  • 19. ROR icon Kavli Institute for the Physics and Mathematics of the Universe

Abstract

We report the discovery of an extremely magnified star at redshift z = 2.65 in the James Webb Space Telescope (JWST) NIRISS pre-imaging of the A2744 galaxy-cluster field. The star's background host galaxy lies on a fold caustic of the foreground lens, and the cluster creates a pair of images of the region close to the lensed star. We identified the bright transient in one of the merging images at a distance of ∼0.″15 from the critical curve by subtracting the JWST F115W and F150W imaging from coadditions of archival Hubble Space Telescope (HST) F105W and F125W images and F140W and F160W images, respectively. Since the time delay between the two images should be only hours, the transient must be the microlensing event of an individual star, as opposed to a luminous stellar explosion that would persist for days to months. Analysis of individual exposures suggests that the star's magnification is not changing rapidly during the observations. From photometry of the point source through the F115W, F150W, and F200W filters, we identify a strong Balmer break, and modeling allows us to constrain the star's temperature to be approximately 7000–12,000 K.

Additional Information

W.C. acknowledges support from NASA HST grant AR-15791. P.L.K. is supported by NSF grant AST-1908823 and NASA/Keck JPL RSA 1644110. R.A.W. acknowledges support from NASA JWST Interdisciplinary Scientist grants NAG5-12460, NNX14AN10G, and 80NSSC18K0200 from GSFC. J.M.D. acknowledges the support of project PGC2018-101814-B-100 (MCIU/AEI/MINECO/FEDER, UE) Ministerio de Ciencia, Investigación y Universidades. This project was funded by the Agencia Estatal de Investigación, Unidad de Excelencia María de Maeztu, ref. MDM-2017-0765. A.K. is supported by scientist grants NAG5-12460, NNX14AN10G, and 80NSSC18K0200 from GSFC. A.Z. and A.K.M. acknowledge support by Grant No. 2020750 from the United States-Israel Binational Science Foundation (BSF) and grant No. 2109066 from the United States National Science Foundation (NSF), and by the Ministry of Science & Technology, Israel. M.B. acknowledges support from the Slovenian national research agency ARRS through grant N1-0238.

Additional details

Identifiers

Eprint ID
118500
Resolver ID
CaltechAUTHORS:20221219-417430800.27

Funding

NASA
HST-AR-15791
NSF
AST-1908823
JPL
RSA 1644110
NASA
NAG5-12460
NASA
NNX14AN10G
NASA
80NSSC18K0200
Binational Science Foundation (USA-Israel)
2020750
Ministerio de Ciencia, Innovación y Universidades (MCIU)
PGC2018-101814-B-100
Agencia Estatal de Investigación
MDM-2017-0765
Slovenian Research Agency
N1-0238

Dates

Created
2023-01-19
Created from EPrint's datestamp field
Updated
2023-01-19
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Infrared Processing and Analysis Center (IPAC)