Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631

Y. Z. Cai; A. Pastorello; M. Fraser; X. F. Wang; A. V. Filippenko; A. Reguitti; K. C. Patra; V. P. Goranskij; E. A. Barsukova; T. G. Brink; N. Elias-Rosa; H. F. Stevance; W. Zheng; Y. Yang; K. E. Atapin; S. Benetti; T. J.L. De Boer; S. Bose; J. Burke; R. Byrne; E. Cappellaro; K. C. Chambers; W. L. Chen; Najmeh Emami; H. Gao; D. Hiramatsu; D. A. Howell; M. E. Huber; E. Kankare; P. L. Kelly; R. Kotak; T. Kravtsov; V. Yu Lander; Z. T. Li; C. C. Lin; P. Lundqvist; E. A. Magnier; E. A. Malygin; N. A. Maslennikova; K. Matilainen; P. A. Mazzali; C. Mccully; J. Mo; S. Moran; M. Newsome; D. V. Oparin; E. Padilla Gonzalez; T. M. Reynolds; N. I. Shatsky; S. J. Smartt; K. W. Smith; M. D. Stritzinger; A. M. Tatarnikov; G. Terreran; R. I. Uklein; G. Valerin; P. J. Vallely; O. V. Vozyakova; R. Wainscoat; S. Y. Yan; J. J. Zhang; T. M. Zhang; S. G. Zheltoukhov; R. Dastidar; M. Fulton; L. Galbany; A. Gangopadhyay; H. W. Ge; C. P. Gutiérrez; H. Lin; K. Misra; Z. W. Ou; I. Salmaso; L. Tartaglia; L. Xiao; X. H. Zhang

doi:10.1051/0004-6361/202244393

Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631

Y. Z. Cai, A. Pastorello, M. Fraser, X. F. Wang, A. V. Filippenko, A. Reguitti, K. C. Patra, V. P. Goranskij, E. A. Barsukova, T. G. Brink, N. Elias-Rosa, H. F. Stevance, W. Zheng, Y. Yang, K. E. Atapin, S. Benetti, T. J.L. De Boer, S. Bose, J. Burke, R. ByrneE. Cappellaro, K. C. Chambers, W. L. Chen, Najmeh Emami, H. Gao, D. Hiramatsu, D. A. Howell, M. E. Huber, E. Kankare, P. L. Kelly, R. Kotak, T. Kravtsov, V. Yu Lander, Z. T. Li, C. C. Lin, P. Lundqvist, E. A. Magnier, E. A. Malygin, N. A. Maslennikova, K. Matilainen, P. A. Mazzali, C. Mccully, J. Mo, S. Moran, M. Newsome, D. V. Oparin, E. Padilla Gonzalez, T. M. Reynolds, N. I. Shatsky, S. J. Smartt, K. W. Smith, M. D. Stritzinger, A. M. Tatarnikov, G. Terreran, R. I. Uklein, G. Valerin, P. J. Vallely, O. V. Vozyakova, R. Wainscoat, S. Y. Yan, J. J. Zhang, T. M. Zhang, S. G. Zheltoukhov, R. Dastidar, M. Fulton, L. Galbany, A. Gangopadhyay, H. W. Ge, C. P. Gutiérrez, H. Lin, K. Misra, Z. W. Ou, I. Salmaso, L. Tartaglia, L. Xiao, X. H. Zhang

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Abstract

We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6×1041 erg s-1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊗ progenitor candidate with log (L/L⊗) = 5.0 dex and Teff 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊗ primary component.

Original language	English (US)
Article number	A4
Journal	Astronomy and Astrophysics
Volume	667
DOIs	https://doi.org/10.1051/0004-6361/202244393
State	Published - Nov 1 2022
Externally published	Yes

Bibliographical note

Publisher Copyright:
© Y.-Z. Cai et al. 2022.

Keywords

Binaries: close
Stars: individual: AT 2021biy
Stars: winds, outflows

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Cai, Y. Z., Pastorello, A., Fraser, M., Wang, X. F., Filippenko, A. V., Reguitti, A., Patra, K. C., Goranskij, V. P., Barsukova, E. A., Brink, T. G., Elias-Rosa, N., Stevance, H. F., Zheng, W., Yang, Y., Atapin, K. E., Benetti, S., De Boer, T. J. L., Bose, S., Burke, J., ... Zhang, X. H. (2022). Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631. Astronomy and Astrophysics, 667, Article A4. https://doi.org/10.1051/0004-6361/202244393

Cai, YZ, Pastorello, A, Fraser, M, Wang, XF, Filippenko, AV, Reguitti, A, Patra, KC, Goranskij, VP, Barsukova, EA, Brink, TG, Elias-Rosa, N, Stevance, HF, Zheng, W, Yang, Y, Atapin, KE, Benetti, S, De Boer, TJL, Bose, S, Burke, J, Byrne, R, Cappellaro, E, Chambers, KC, Chen, WL, Emami, N, Gao, H, Hiramatsu, D, Howell, DA, Huber, ME, Kankare, E, Kelly, PL, Kotak, R, Kravtsov, T, Lander, VY, Li, ZT, Lin, CC, Lundqvist, P, Magnier, EA, Malygin, EA, Maslennikova, NA, Matilainen, K, Mazzali, PA, Mccully, C, Mo, J, Moran, S, Newsome, M, Oparin, DV, Padilla Gonzalez, E, Reynolds, TM, Shatsky, NI, Smartt, SJ, Smith, KW, Stritzinger, MD, Tatarnikov, AM, Terreran, G, Uklein, RI, Valerin, G, Vallely, PJ, Vozyakova, OV, Wainscoat, R, Yan, SY, Zhang, JJ, Zhang, TM, Zheltoukhov, SG, Dastidar, R, Fulton, M, Galbany, L, Gangopadhyay, A, Ge, HW, Gutiérrez, CP, Lin, H, Misra, K, Ou, ZW, Salmaso, I, Tartaglia, L, Xiao, L & Zhang, XH 2022, 'Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631', Astronomy and Astrophysics, vol. 667, A4. https://doi.org/10.1051/0004-6361/202244393

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title = "Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631",

abstract = "We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6×1041 erg s-1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊗ progenitor candidate with log (L/L⊗) = 5.0 dex and Teff 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊗ primary component.",

keywords = "Binaries: close, Stars: individual: AT 2021biy, Stars: winds, outflows",

author = "Cai, {Y. Z.} and A. Pastorello and M. Fraser and Wang, {X. F.} and Filippenko, {A. V.} and A. Reguitti and Patra, {K. C.} and Goranskij, {V. P.} and Barsukova, {E. A.} and Brink, {T. G.} and N. Elias-Rosa and Stevance, {H. F.} and W. Zheng and Y. Yang and Atapin, {K. E.} and S. Benetti and {De Boer}, {T. J.L.} and S. Bose and J. Burke and R. Byrne and E. Cappellaro and Chambers, {K. C.} and Chen, {W. L.} and Najmeh Emami and H. Gao and D. Hiramatsu and Howell, {D. A.} and Huber, {M. E.} and E. Kankare and Kelly, {P. L.} and R. Kotak and T. Kravtsov and Lander, {V. Yu} and Li, {Z. T.} and Lin, {C. C.} and P. Lundqvist and Magnier, {E. A.} and Malygin, {E. A.} and Maslennikova, {N. A.} and K. Matilainen and Mazzali, {P. A.} and C. Mccully and J. Mo and S. Moran and M. Newsome and Oparin, {D. V.} and {Padilla Gonzalez}, E. and Reynolds, {T. M.} and Shatsky, {N. I.} and Smartt, {S. J.} and Smith, {K. W.} and Stritzinger, {M. D.} and Tatarnikov, {A. M.} and G. Terreran and Uklein, {R. I.} and G. Valerin and Vallely, {P. J.} and Vozyakova, {O. V.} and R. Wainscoat and Yan, {S. Y.} and Zhang, {J. J.} and Zhang, {T. M.} and Zheltoukhov, {S. G.} and R. Dastidar and M. Fulton and L. Galbany and A. Gangopadhyay and Ge, {H. W.} and Guti{\'e}rrez, {C. P.} and H. Lin and K. Misra and Ou, {Z. W.} and I. Salmaso and L. Tartaglia and L. Xiao and Zhang, {X. H.}",

note = "Publisher Copyright: {\textcopyright} Y.-Z. Cai et al. 2022.",

year = "2022",

month = nov,

day = "1",

doi = "10.1051/0004-6361/202244393",

language = "English (US)",

volume = "667",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

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TY - JOUR

T1 - Forbidden hugs in pandemic times

T2 - III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631

AU - Cai, Y. Z.

AU - Pastorello, A.

AU - Fraser, M.

AU - Wang, X. F.

AU - Filippenko, A. V.

AU - Reguitti, A.

AU - Patra, K. C.

AU - Goranskij, V. P.

AU - Barsukova, E. A.

AU - Brink, T. G.

AU - Elias-Rosa, N.

AU - Stevance, H. F.

AU - Zheng, W.

AU - Yang, Y.

AU - Atapin, K. E.

AU - Benetti, S.

AU - De Boer, T. J.L.

AU - Bose, S.

AU - Burke, J.

AU - Byrne, R.

AU - Cappellaro, E.

AU - Chambers, K. C.

AU - Chen, W. L.

AU - Emami, Najmeh

AU - Gao, H.

AU - Hiramatsu, D.

AU - Howell, D. A.

AU - Huber, M. E.

AU - Kankare, E.

AU - Kelly, P. L.

AU - Kotak, R.

AU - Kravtsov, T.

AU - Lander, V. Yu

AU - Li, Z. T.

AU - Lin, C. C.

AU - Lundqvist, P.

AU - Magnier, E. A.

AU - Malygin, E. A.

AU - Maslennikova, N. A.

AU - Matilainen, K.

AU - Mazzali, P. A.

AU - Mccully, C.

AU - Mo, J.

AU - Moran, S.

AU - Newsome, M.

AU - Oparin, D. V.

AU - Padilla Gonzalez, E.

AU - Reynolds, T. M.

AU - Shatsky, N. I.

AU - Smartt, S. J.

AU - Smith, K. W.

AU - Stritzinger, M. D.

AU - Tatarnikov, A. M.

AU - Terreran, G.

AU - Uklein, R. I.

AU - Valerin, G.

AU - Vallely, P. J.

AU - Vozyakova, O. V.

AU - Wainscoat, R.

AU - Yan, S. Y.

AU - Zhang, J. J.

AU - Zhang, T. M.

AU - Zheltoukhov, S. G.

AU - Dastidar, R.

AU - Fulton, M.

AU - Galbany, L.

AU - Gangopadhyay, A.

AU - Ge, H. W.

AU - Gutiérrez, C. P.

AU - Lin, H.

AU - Misra, K.

AU - Ou, Z. W.

AU - Salmaso, I.

AU - Tartaglia, L.

AU - Xiao, L.

AU - Zhang, X. H.

PY - 2022/11/1

Y1 - 2022/11/1

N2 - We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6×1041 erg s-1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊗ progenitor candidate with log (L/L⊗) = 5.0 dex and Teff 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊗ primary component.

AB - We present an observational study of the luminous red nova (LRN) AT 2021biy in the nearby galaxy NGC 4631. The field of the object was routinely imaged during the pre-eruptive stage by synoptic surveys, but the transient was detected only at a few epochs from ∼231 days before maximum brightness. The LRN outburst was monitored with unprecedented cadence both photometrically and spectroscopically. AT 2021biy shows a short-duration blue peak, with a bolometric luminosity of ∼1.6×1041 erg s-1, followed by the longest plateau among LRNe to date, with a duration of 210 days. A late-time hump in the light curve was also observed, possibly produced by a shell-shell collision. AT 2021biy exhibits the typical spectral evolution of LRNe. Early-time spectra are characterised by a blue continuum and prominent H emission lines. Then, the continuum becomes redder, resembling that of a K-type star with a forest of metal absorption lines during the plateau phase. Finally, late-time spectra show a very red continuum (TBB ≈ 2050 K) with molecular features (e.g., TiO) resembling those of M-type stars. Spectropolarimetric analysis indicates that AT 2021biy has local dust properties similar to those of V838 Mon in the Milky Way Galaxy. Inspection of archival Hubble Space Telescope data taken on 2003 August 3 reveals a ∼20 M⊗ progenitor candidate with log (L/L⊗) = 5.0 dex and Teff 5900 K at solar metallicity. The above luminosity and colour match those of a luminous yellow supergiant. Most likely, this source is a close binary, with a 17-24 M⊗ primary component.

KW - Binaries: close

KW - Stars: individual: AT 2021biy

KW - Stars: winds, outflows

UR - http://www.scopus.com/inward/record.url?scp=85142878213&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85142878213&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202244393

DO - 10.1051/0004-6361/202244393

M3 - Article

AN - SCOPUS:85142878213

SN - 0004-6361

VL - 667

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A4

ER -

Forbidden hugs in pandemic times: III. Observations of the luminous red nova AT 2021biy in the nearby galaxy NGC 4631

Abstract

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