Cannot access "Particle Creation Time" in ART data for Stellar particles

[AsierLambarri]

For modellig the luminosity of stellar particles i am following the standard SSP approach, for which i need the ages of stellar particles. In, at least all of the yt4.X versions i have encountered that the "particle_creation_time" cannot be generated correctly. My code is the following:

import yt

ds = yt.load("sample_data.d")

ds.add_field(
  ("stars", "age"),
  function=lambda field, data: ds.current_time - data["stars", "particle_creation_time"],
 units="Gyr"
)

ad = ds.all_data()
ad["stars", "age"]

The error message is the following: UnitInconsistencyError: Expected all unyt_array arguments to have identical units. Received mixed units (dimensionless, Gyr).

The issue is that the variable interp_tb defined in line 292 of frontends/art/io.py is set to have units of "Gyr" that seem to not match the units of data. I have found that setting interp_tb to be dimensionless solves this UnitInconsistencyError and returns stellar ages that are plaussible. I could fix this issue in a PR.

Sample Data for reproduction: https://users.flatironinstitute.org/~chayward/agora_public_release/PaperIV/ART-I/

Dependencies:

numpy1.26.4
yt4.X