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Reaching for the stars – JWST/NIRSpec spectroscopy of a lensed star candidate at z = 4.76.
- Source :
- Monthly Notices of the Royal Astronomical Society: Letters; Jan2024, Vol. 527 Issue 1, pL7-L13, 7p
- Publication Year :
- 2024
-
Abstract
- We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of z <subscript>phot</subscript> ≃ 4.8, previously detected in JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015 (z  = 0.591). The spectroscopic observation allows us to precisely measure the redshift of the host arc at z <subscript>spec</subscript> = 4.758 ± 0.004, and the star's spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature |$T_{\mathrm{eff,B}}\simeq 15\, 000$| K with either a redder F-type companion (|$T_{\mathrm{eff,F}}\simeq 6\, 250$| K) or significant dust attenuation (A<subscript>V</subscript> ≃ 0.82) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, r ≲ 0.5 pc, could indicate that this scenario is somewhat less likely – albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only ∼1.2 Gyr old showcases the ability of JWST to study early stars through extreme lensing. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 17453925
- Volume :
- 527
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society: Letters
- Publication Type :
- Academic Journal
- Accession number :
- 173856369
- Full Text :
- https://doi.org/10.1093/mnrasl/slad135