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

Chen, Wenlei and Kelly, Patrick L. and Treu, Tommaso and Wang, Xin and Roberts-Borsani, Guido and Keen, Allison and Windhorst, Rogier A. and Zhou, Rui and Bradač, Maruša and Brammer, Gabriel B. and Strait, Victoria and Broadhurst, Tom J. and Diego, Jose M. and Frye, Brenda L. and Meena, Ashish K. and Zitrin, Adi and Pascale, Massimo and Castellano, Marco and Marchesini, Danilo and Morishita, Takahiro and Yang, Lilan (2022) Early Results from GLASS-JWST. VIII. An Extremely Magnified Blue Supergiant Star at Redshift 2.65 in the A2744 Cluster Field. Astrophysical Journal Letters, 940 (2). Art. No. L54. ISSN 2041-8205. doi:10.3847/2041-8213/ac9585.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Chen, Wenlei0000-0003-1060-0723
Kelly, Patrick L.0000-0003-3142-997X
Treu, Tommaso0000-0002-8460-0390
Wang, Xin0000-0002-9373-3865
Roberts-Borsani, Guido0000-0002-4140-1367
Keen, Allison0000-0002-9800-9868
Windhorst, Rogier A.0000-0001-8156-6281
Zhou, Rui0000-0003-0031-9241
Bradač, Maruša0000-0001-5984-0395
Brammer, Gabriel B.0000-0003-2680-005X
Strait, Victoria0000-0002-6338-7295
Broadhurst, Tom J.0000-0002-8785-8979
Diego, Jose M.0000-0001-9065-3926
Frye, Brenda L.0000-0003-1625-8009
Meena, Ashish K.0000-0002-7876-4321
Zitrin, Adi0000-0002-0350-4488
Pascale, Massimo0000-0002-2282-8795
Castellano, Marco0000-0001-9875-8263
Marchesini, Danilo0000-0001-9002-3502
Morishita, Takahiro0000-0002-8512-1404
Yang, Lilan0000-0002-8434-880X
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.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
JPLRSA 1644110
Binational Science Foundation (USA-Israel)2020750
Ministerio de Ciencia, Innovación y Universidades (MCIU)PGC2018-101814-B-100
Agencia Estatal de InvestigaciónMDM-2017-0765
Slovenian Research AgencyN1-0238
Issue or Number:2
Record Number:CaltechAUTHORS:20221219-417430800.27
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118500
Deposited By: Research Services Depository
Deposited On:19 Jan 2023 20:29
Last Modified:19 Jan 2023 20:29

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