#astronomy A Close by Stellar Stream Will get Carded

August 25, 2019 - Comment

Pisces–Eridanus could attempt to cross itself off as a billion years outdated, however scientists are calling its bluff. The Transiting Exoplanet Survey Satellite tv for pc (TESS) has now carded this close by stream of stars, revealing that it’s truly a relative child! This picture of the night time sky, centered on the South Galactic


Pisces–Eridanus could attempt to cross itself off as a billion years outdated, however scientists are calling its bluff. The Transiting Exoplanet Survey Satellite tv for pc (TESS) has now carded this close by stream of stars, revealing that it’s truly a relative child!

Pisces–Eridanus stellar stream

This picture of the night time sky, centered on the South Galactic Pole, exhibits the places of the members of the Pisces–Eridanus stellar stream as pink dots that span the southern galactic hemisphere. A brand new examine suggests this stream could also be a lot youthful than initially thought.
Stefan Meingast / ESA / Gaia / DPAC

On the lookout for Age

Stellar stream (art)

Artist’s impression of a stellar stream arcing excessive within the Milky Method’s halo. The Pisces-Eridanus stream has been found a lot nearer to Earth than these illustrated right here.
NASA

Stellar streams are faint associations of stars that have been born collectively and transfer collectively, however they’ve been stretched into lengthy tails throughout the sky. Some stellar streams possible originated as dense, compact clusters of stars that have been pulled into streams by tidal interactions; others could have fashioned in a decentralized trend and been unfold additional aside with time.

To know the evolution of stars in streams and clusters, we use benchmarks: pattern star clusters of various ages that we’ve explored in excessive element. Sadly, most star clusters and associations that we will observe intently are younger. Identified older clusters all lie at bigger distances — the 1-Gyr-old benchmark cluster NGC 6811, for instance, is three,600 light-years away — which limits what we will be taught from them.

Can I See Your ID?

Open cluster distance vs. age

Plot of distance vs. age for a number of benchmark open star clusters. Pisces–Eridanus was initially recognized as being 1 Gyr outdated (Meingast et al. 2019 pink marker on the plot), which might make it the oldest cluster inside 300 laptop (~1,000 light-years).
Curtis et al. 2019

It’s because of this that the current discovery of the Pisces–Eridanus stream — a faint stellar stream that spans 120° within the sky, is situated simply 260–740 light-years away, and was initially aged at 1 billion years — was met with a heat welcome. This unexpectedly shut stream may show to be a crucial new 1-Gyr-old benchmark that may assist us higher perceive stellar evolution.

Appearing as bouncers for the 1 Gyr+ membership, nonetheless, is a staff of astronomers led by Jason Curtis (NSF Astronomy and Astrophysics Postdoctoral Fellow at Columbia College). They’ve got down to test that Pisces–Eridanus is as outdated because it initially led us to consider — and it seems we’ve been deceived.

Revealing Rotation

Curtis and collaborators used TESS gentle curves of greater than 100 members of the Pisces-Eridanus stream to establish how quickly the celebs are spinning. In a course of referred to as gyrochronology, the authors used the celebs’ measured rotation charges to find out the age of the stream by evaluating the distribution of rotation intervals to the distributions for benchmark clusters with identified ages.

Rotation period distributions

Rotation interval distributions for Pisces–Eridanus (pink) and three benchmark clusters: 120 Myr Pleiades (blue), 670 Myr Praesepe (cyan), and 1 Gyr NGC 6811 (orange). Pisces–Eridanus stars clearly overlap with the Pleiades stars, indicating the 2 clusters have the identical age.
Tailored from Curtis et al. 2019

They discovered that Pisces-Eridanus’s distribution exactly overlapped the distribution for the celebs of the Pleiades, indicating that these two teams are the identical age: a mere 120 million years outdated!

Curtis and collaborators then used Gaia knowledge mixed with previous radial-velocity measurements to hunt for brand spanking new members of the Pisces-Eridanus stream. They recognized 34 new high-mass candidate members — and the colours and brightnesses of those stars additionally assist a younger age of round 120 million years.

A Goal for Planet-Looking

Does the Pisces-Eridanus stream’s newly revealed youth imply that it’s no good to us in spite of everything? In no way, in keeping with Curtis and collaborators. One explicit worth of this stream is as an exploration floor within the hunt for exoplanets; planet discoveries right here will permit us to study planet formation in a singular, diffuse atmosphere.

What else have we discovered? This examine marks the primary gyrochronology examine performed utilizing TESS knowledge — demonstrating the precious position TESS has to play sooner or later as we proceed to work to grasp stellar and planetary beginning and evolution.

Quotation

“TESS Reveals that the Close by Pisces–Eridanus Stellar Stream is just 120 Myr Previous,” Jason L. Curtis et al 2019 AJ 158 77. doi:10.3847/1538-3881/ab2899

This submit initially appeared on AAS Nova, which options analysis highlights from the journals of the American Astronomical Society.



Supply hyperlink

Comments

Comments are disabled for this post.