APOD: T Tauri and Hind's Variable Nebula (2022 Feb 10)

[APOD Robot]

T Tauri and Hind's Variable Nebula

Explanation: The star with an orange tint near top center in this dusty telescopic frame is T Tauri, prototype of the class of T Tauri variable stars. Next to it (right) is a yellow cosmic cloud historically known as Hind's Variable Nebula (NGC 1555). About 650 light-years away, at the boundary of the local bubble and the Taurus molecular cloud, both star and nebula are seen to vary significantly in brightness but not necessarily at the same time, adding to the mystery of the intriguing region. T Tauri stars are now generally recognized as young (less than a few million years old), sun-like stars still in the early stages of formation. To further complicate the picture, infrared observations indicate that T Tauri itself is part of a multiple system and suggest that the associated Hind's Nebula may also contain a very young stellar object. The well-composed image spans about 8 light-years at the estimated distance of T Tauri.

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[Ann]

T Tauri and Hind's Variable Nebula. Image Credit & Copyright:
Dawn Lowry, Gian Lorenzo Ferretti, Ewa Pasiak and Terry Felty

Closeup of T Tauri and Hind's Variable Nebula in today's APOD.

APOD Robot wrote:
The star with an orange tint near top center in this dusty telescopic frame is T Tauri, prototype of the class of T Tauri variable stars. Next to it (right) is a yellow cosmic cloud historically known as Hind's Variable Nebula (NGC 1555).

Wow! You could have fooled me. A "yellow" cosmic cloud next to T Tauri? When I first saw the image, I thought, Wow, I didn't know that there was a small pink emission hydrogen alpha cloud next to T Tauri!

T Tauri and Hind's Variable Nebula (right). Image: Adam Block/Mount Lemmon SkyCenter/University of Arizona

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Red supergiant star Antares and its yellow reflection nebula. Image: ESO/K. Ohnaka

But when I looked at a number of other images of T Tauri and Hind's Variable Nebula, I could see that both the star and the nebula do look orange to yellow-orange in all of them. The B-V index of T Tauri is +1.1, which is a lot redder than the Sun, whose B-V is between +0.6 and +0.7. So clearly Hind's Variable Nebula is another yellow reflection nebula, somewhat similar to (but very much smaller than) the Antares Nebula. I apologize for the white color of deeply yellow-orange Antares, which has been overexposed to a white color in the picture I posted.

Ann

[orin stepanek]

Young Star Nebula

Stars less than a million years old! Just Beautiful!

[neufer]

Reported Location of NGC 1554 by Otto Wilhelm von Struve relative to NGC 1555

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<<The nebula NGC 1554 [a.k.a., Struve's Lost Nebula] is believed to be associated with T Tauri. In the 1860s, Hind's nebula had faded from view for nearly all astronomers on Earth, including Hind himself, but Otto Wilhelm von Struve, having the third most powerful telescope in the world at the time, could still see it. In 1868, Struve reported a patch of nebulosity that he believed to be distinct from Hind's Nebula, and this was confirmed by a contemporary, Heinrich Louis d'Arrest. Over the course of the next 10-20 years, the nebula faded from view and Hind's Nebula came back into view of most astronomers at the same time. It is likely Struve truly did observe something, especially considering d'Arrest confirmed it, but as of 2021 there is no agreed upon explanation for what caused this phenomena.

The exact dynamics of the outflow system of T Tauri, particularly its evolution, is poorly understood. It is possible some sort of interaction between the jets in the past may have caused the phenomena that Struve observed, but more data on at least the orbital constraints of T Tau N and how the jets interact currently will be needed before any concrete theory can be reached.>>