TY - JOUR
T1 - Reaching for the stars – JWST/NIRSpec spectroscopy of a lensed star candidate at z = 4.76
AU - Furtak, Lukas J.
AU - Meena, Ashish K.
AU - Zackrisson, Erik
AU - Zitrin, Adi
AU - Brammer, Gabriel B.
AU - Coe, Dan
AU - Diego, José M.
AU - Eldridge, Jan J.
AU - Jiménez-Teja, Yolanda
AU - Kokorev, Vasily
AU - Ricotti, Massimo
AU - Welch, Brian
AU - Windhorst, Rogier A.
AU - Abdurro’uf,
AU - Andrade-Santos, Felipe
AU - Bhatawdekar, Rachana
AU - Bradley, Larry D.
AU - Broadhurst, Tom
AU - Chen, Wenlei
AU - Conselice, Christopher J.
AU - Dayal, Pratika
AU - Frye, Brenda L.
AU - Fujimoto, Seiji
AU - Hsiao, Tiger Y.Y.
AU - Kelly, Patrick L.
AU - Mahler, Guillaume
AU - Mandelker, Nir
AU - Norman, Colin
AU - Oguri, Masamune
AU - Pirzkal, Norbert
AU - Postman, Marc
AU - Ravindranath, Swara
AU - Vanzella, Eros
AU - Wilkins, Stephen M.
N1 - Publisher Copyright:
© 2024 Oxford University Press. All rights reserved.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of zphot ≃ 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 zspec = 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 Teff,B ≃ 15 000 K with either a redder F-type companion (Teff,F ≃ 6 250 K) or significant dust attenuation (AV ≃ 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.
AB - We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of zphot ≃ 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 zspec = 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 Teff,B ≃ 15 000 K with either a redder F-type companion (Teff,F ≃ 6 250 K) or significant dust attenuation (AV ≃ 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.
KW - galaxies: high-redshift
KW - galaxies: star clusters: general
KW - gravitational lensing: micro
KW - gravitational lensing: strong
KW - stars: individual: MACS0647-star-1
KW - stars: massive
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U2 - 10.1093/mnrasl/slad135
DO - 10.1093/mnrasl/slad135
M3 - Article
AN - SCOPUS:85175420810
SN - 1745-3925
VL - 527
SP - L7-L13
JO - Monthly Notices of the Royal Astronomical Society: Letters
JF - Monthly Notices of the Royal Astronomical Society: Letters
IS - 1
ER -