GJ 3929: High-precision Photometric and Doppler Characterization of an Exo-Venus and Its Hot, Mini-Neptune-mass Companion

Corey Beard, Paul Robertson, Shubham Kanodia, Jack Lubin, Caleb I. Cañas, Arvind F. Gupta, Rae Holcomb, Sinclaire Jones, Jessica E. Libby-Roberts, Andrea S.J. Lin, Suvrath Mahadevan, Guđmundur Stefánsson, Chad F. Bender, Cullen H. Blake, William D. Cochran, Michael Endl, Mark Everett, Eric B. Ford, Connor Fredrick, Samuel HalversonLeslie Hebb, Dan Li, Sarah E. Logsdon, Jacob Luhn, Michael W. McElwain, Andrew J. Metcalf, Joe P. Ninan, Jayadev Rajagopal, Arpita Roy, Maria Schutte, Christian Schwab, Ryan C. Terrien, John Wisniewski, Jason T. Wright

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We detail the follow-up and characterization of a transiting exo-Venus identified by TESS, GJ 3929b (TOI-2013b), and its nontransiting companion planet, GJ 3929c (TOI-2013c). GJ 3929b is an Earth-sized exoplanet in its star’s Venus zone (P b = 2.616272 ± 0.000005 days; Sb = 17.3 − 0.7 + 0.8 S ) orbiting a nearby M dwarf. GJ 3929c is most likely a nontransiting sub-Neptune. Using the new, ultraprecise NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak National Observatory, we are able to modify the mass constraints of planet b reported in previous works and consequently improve the significance of the mass measurement to almost 4σ confidence (M b = 1.75 ± 0.45 M ). We further adjust the orbital period of planet c from its alias at 14.30 ± 0.03 days to the likely true period of 15.04 ± 0.03 days, and we adjust its minimum mass to m sin i = 5.71 ± 0.92 M . Using the diffuser-assisted ARCTIC imager on the ARC 3.5 m telescope at Apache Point Observatory, in addition to publicly available TESS and LCOGT photometry, we are able to constrain the radius of planet b to R p = 1.09 ± 0.04 R . GJ 3929b is a top candidate for transmission spectroscopy in its size regime (TSM = 14 ± 4), and future atmospheric studies of GJ 3929b stand to shed light on the nature of small planets orbiting M dwarfs.

Original languageEnglish (US)
Article number55
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'GJ 3929: High-precision Photometric and Doppler Characterization of an Exo-Venus and Its Hot, Mini-Neptune-mass Companion'. Together they form a unique fingerprint.

Cite this