VLA radio detection of Nova Scorpii 2024 (V1723 Sco)

ATel #16492; Isabella Molina (MSU), Kirill Sokolovsky (UIUC), Elias Aydi, Peter Craig, Laura Chomiuk, Jay Strader (MSU), Jennifer Sokoloski (Columbia), Justin Linford, Montana Williams (NRAO), Koji Mukai (NASA/GSFC), Michael Rupen (NRC)
on 28 Feb 2024; 17:57 UT
Credential Certification: Kirill Sokolovsky (kirx@scan.sai.msu.ru)

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Nova V1723 Sco was discovered 2024-02-08.827 UT at a magnitude of 7.8 by Andrew Pearce and on 2024-02-09.836 by Yukio Sakurai (CBET #5346). It is located at RA: 17:26:18.078 Dec: -38:09:36.31 (ATel #16444). It was spectroscopically classified as a nova near visible peak with the 4.1m SOAR telescope (Cerro Pachon, Chile; ATel #16440). Further photometry and spectroscopy of the nova was discussed in ATel #16454. Fermi-LAT observed bright gamma ray emission from V1723 Sco on 2024-02-09.50 (ATel #16439, #16441). The NuSTAR observation between 2024-02-10.299 and 2024-02-11.767 resulted in a non-detection (ATel #16444). The nova was first detected with Swift/XRT on 2024-02-22.268, 13 days after the eruption (ATel #16484).

Radio monitoring of nova V1723 Sco was initiated with the Karl G. Jansky Very Large Array (VLA) starting on 2024-02-17 (7.2 days after discovery). The VLA was in C configuration and observations were taken in S, C, Ku, and Ka bands (2.0 - 38.0 GHz). Each observing band was separated into two sidebands for improved spectral coverage. The nova was clearly detected in all bands except the lower S band (2.6 GHz). The estimated spectral index of 0.5 indicates that the radio emission is partly optically thick.

The multi-color photometry of V1723 Sco, submitted to the AAVSO International Database, enables the estimation of reddening E(B-V) between 1.1 and 1.5. This assumes an intrinsic color of (B-V)_0=-0.02, typical for novae two magnitudes below peak (van den Bergh & Younger 1987, A&AS, 70, 125). Combining E(B-V) values with the 3D dust map of Marshall (2006, A&A, 453, 635) we estimate the distance to V1723 Sco of about 4 kpc.

The brightness temperature (T_B) was estimated using this distance estimate and an expansion velocity of 3200 km/s (ATel #16454).

 
Freq. S    S_err  T_B 
(GHz) (mJy) (mJy) (K) 
2.6  0.084 0.088 non-detection - 
3.4  0.281 0.031 9.7 x 10^5 
5.1  0.327 0.026 5.0 x 10^5 
7.0  0.382 0.023 3.1 x 10^5 
13.7 0.495 0.016 1.1 x 10^5 
16.5 0.517 0.037 7.6 x 10^4 
31.1 0.898 0.096 3.7 x 10^4 
34.9 1.034 0.122 3.4 x 10^4 

Radio observations of V1723 Sco are ongoing, and we encourage multiple wavelength observations of the nova. The observations reported here were obtained with the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.