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TOI-3785 Exoplanet System

A Low-Density Neptune Orbiting an M2-Dwarf Star //

TOI-3785 is a real exoplanet system located 259 light years from Earth, consisting of one star and one known planet. The star, TOI-3785, is an M2V red dwarf weighing in at 0.52 solar masses and 0.50 solar radii, with a surface temperature of 3576 K and luminosity 3.67% that of the Sun. It is estimated to be 8 billion years old and has enjoyed more time to evolve away from the volatility of its youth. TOI-3785 is now believed to be a fairly slow-rotating, inactive star without significant flare activity, and within the domain of cool, dim dwarfs.

Discovered in 2023, TOI-3785 b is a Neptune-like planet around TOI-3785 with 14.95 Earth masses and 5.14 Earth radii. It hugs its star in a slightly eccentric 4.67-day orbit and has a calculated equilibrium temperature of 582 K. Interestingly, although red dwarfs are the most common stars in our galaxy, only eight planets similar to TOI-3785 b have been confirmed to orbit one at the time of writing. One explanation for this "Neptune scarcity" is that once protoplanets reach a critical mass, they tend to grow exponentially into Jupiter-mass gas giants. But in some cases as with TOI-3785 b, something must have put the brakes on this runaway mass gain. Further investigating its composition and finding similar planets would shed light on the evolutionary pathways of these red dwarf Neptunes. Lastly, TOI-3785 b is also a promising target for future atmospheric studies. The inactivity of its host star makes stellar interference less likely, accentuating any chemical signals from the planet's atmosphere.

In this simulation, the characteristics of TOI-3785 b are replicated from literature wherever possible or inferred in cases of knowledge gaps:

• I've envisioned TOI-3785 b as a tidally locked warm Neptune with an average temperature of ~490 K.
  
• Based on modelling, a substantial 20% of the planet's mass is hydrogen/helium, which is replicated in the simulation. I've made up the remainder with water and small a amount of silicate/iron.
  
• Based on atmospheric studies of similar exoplanets GJ 3470 b and GJ 436 b, TOI-3785 b likely possesses a relatively featureless "hazy" atmosphere. This was difficult to capture in-game, as it felt lazy to use a single colour for the whole planet. Thus, I opted for a low-albedo, blue-grey design with subtle gradients over 50 cloud bands to compromise between realism and aesthetics.

2MASS J08433613+6304413, TIC 458419328, TOI-3785, Gaia DR2 1044013542142711296

• Powers, L.C., Libby-Roberts, J., Lin, A.S., Cañas, C.I., Kanodia, S., Mahadevan, S., Ninan, J.P., Stefánsson, G., Gupta, A.F., Jones, S. and Kobulnicky, H.A., 2023. TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star. arXiv preprint arXiv:2304.04730.
  
• Planet toi-3785 B (2023) The Extrasolar Planet Encyclopaedia - TOI-3785 b. Available at: http://exoplanet.eu/catalog/toi-3785_b/ (Accessed: April 25, 2023).