When stars are born, they temporarily surround themselves with a protoplanetary disk and do not yet ignite their thermonuclear reactions. Then we talk about these protostars as T-Tauri stars. To study protoplanetary disks, Hubble zoomed into a triple system with a protostar, HP Tau.
It's true that its shape has remained for years, and although the James Webb Space Telescope has been in service since 2022 until now, NASA periodically reveals images taken by the telescope. HubbleHubble Which are presented mainly for their aesthetic beauty, but can also be commented on for the astrophysics they illustrate.
The latest involves a reflection nebula located about 550 light-years away in the galaxy Constellation TaurusConstellation Taurus. It clearly shows a tripartite systemVariable starsVariable stars HPHP Tau, HPtau G2, and HPtau G3. These are the T-Tauri type stars that Hubble has made it possible to study for consideration Accumulation diskAccumulation disk. But before we look at this picture, we can take the opportunity to talk a little about T-Tauri-type stars.
It all started about them with the discovery of another nebula in the constellation Taurus byastronomerastronomer British John Russell Hind in 1852. Called NGCNGC 1555, and is about 470 light years away from us sunsun In the Milky Way. In modern images, it clearly appears to be a reflection nebula illuminated by a star colorcolor orange. This star in the Hind Nebula is called T-Tauri and serves as a reference for defining this type of star. His studies in InfraredInfrared He revealed that it was actually a tripartite system.
T-Tauri, protostars
Today we know that it is ProtostarsProtostarsThis means that they are young, a few million years old at most, and have not yet reached adulthood Main sequenceMain sequence Where there are stars like the sun.
Today we also know that stars form cloudsclouds Dense, cold, as well as turbulent molecules that are in conditions that allow them to do so CollapsesCollapses gravity. When the cloud breaks up, it produces a small, rotating nebula. At the heart of these nebulae and because of the rotation that opposes it Centrifugal forceCentrifugal force When gravitational contraction is exerted, an accretion disk forms as planets are born around a protostar that is heated by the pressure generated by the contraction, but whose central temperature is not high enough at its center for the lights that will set off thermonuclear reactions to come on. It is a new star on the main sequence.
HP Tau as seen by Hubble
there ThemeTheme The contracting nebula first falls onto the protoplanetary disk before joining the central protostar, hence the name accretion disk. During this stage, the protostar is unstable and large SunspotsSunspotsin whicha stara star Subject to fluctuations brightnessbrightness Both periodic and random. NASA's press release on the subject specifies that these ” The random variations may be due to the chaotic nature of the developing young star, such as instabilities in the dust and accretion disk GasGas Around the star, material from this disk falls on the star, is consumed, and explodes on the surface of the star. The periodic changes may be the result of the appearance and disappearance of giant, rotating sunspots “.
Here, above, is an image of the triple star system T-Tauri observed Hubblethe protostar HP Tau has MassMass Comparable to that of the Sun.
