At temperatures below the lambda point, its bosonic isotope transitions to a superfluid.
In 2011, researchers at the TRUMF accelerator in Vancouver demonstrated that this element exhibits a "disguised" form when one of its electrons was replaced with a muon. One experiment rotated a container of this element around a wire, and a decrease in its rotational inertia was determined to be an indicator of a phase transition into a "superglass." One form of this element has the highest known thermal conductivity and heat travels through it in an entropy wave called "second sound." The spectrum of this element possesses a very prominent yellow Frauenhoffer  line and was named D3 thanks to its similarity to those in sodium. Osheroff and Lee did notable work on an isotope of it that forms fermionic condensates. At temperatures below the lambda point, its bosonic isotope transitions to a superfluid. With its nucleus comprising the alpha particle, for 10 points, name this second element on the periodic table.
In 2011, researchers at the TRUMF accelerator in Vancouver demonstrated that this element exhibits a "disguised" form when one of its electrons was replaced with a muon.
helium