That’s mostly because the heavier and hotter the object, the easier they are to detect by various means. We’ve only recently been able to detect Y-dwarfs and measure their spectral/chemical properties. We still cannot detect Jupiter-size Y-dwarfs beyond our solar system. Jupiter is analogous to the chemical and spectral properties that we’ve seen in these larger dwarf stars. However, that’s only the outer atmosphere, and that alone isn’t enough to conclude that Jupiter is a star.
The Juno mission has used gravity data to confirm that Jupiter’s hydrogen plasma has fully dissolved what was once the planetary nucleus around which the hydrogen accreted. This is the interior transition to stellar morphology.
Similarly, the Cassini mission has used ring seismology (studying waves raised in the rings by planetary seismology and mass anomalies) to confirm that Saturn has a partially dissolved planetary core. Saturn is an object that can be classified as neither a planet nor a star, and represents a class of transition objects straddling the non-binary border between these genres of objects.
See the following previous comment threads where I’ve fleshed out this argument in more detail and with references:
That’s mostly because the heavier and hotter the object, the easier they are to detect by various means. We’ve only recently been able to detect Y-dwarfs and measure their spectral/chemical properties. We still cannot detect Jupiter-size Y-dwarfs beyond our solar system. Jupiter is analogous to the chemical and spectral properties that we’ve seen in these larger dwarf stars. However, that’s only the outer atmosphere, and that alone isn’t enough to conclude that Jupiter is a star.
The Juno mission has used gravity data to confirm that Jupiter’s hydrogen plasma has fully dissolved what was once the planetary nucleus around which the hydrogen accreted. This is the interior transition to stellar morphology.
Similarly, the Cassini mission has used ring seismology (studying waves raised in the rings by planetary seismology and mass anomalies) to confirm that Saturn has a partially dissolved planetary core. Saturn is an object that can be classified as neither a planet nor a star, and represents a class of transition objects straddling the non-binary border between these genres of objects.
See the following previous comment threads where I’ve fleshed out this argument in more detail and with references:
https://sh.itjust.works/comment/14345115
https://sh.itjust.works/comment/15877252