Skip to main content

A FRESH LOOK AT KEPLER-444’S ANCIENT PLANETARY SYSTEM

 From  Sky & Telescope,

By  - ASS NOVA,

Edited by - Amal Udawatta,

image of the three stars in the Kepler-444 system

Artist's impression of a star orbited by five planets.
NASA / JPL-Caltech





Astronomers have just taken a closer look at an unusual system containing three stars and at least five planets. In doing so they may have solved a mystery around its formation. The system, known as Kepler-444, is also around 11 billion years old, showing that such systems can be stable over a significant fraction of the universe’s current age.

ONE SYSTEM, THREE STARS, FIVE PLANETS

Located 117 light-years away toward the constellation Lyra, the system is centered around the K0 star Kepler-444 A. Then there’s a tight-knit binary pair of M-type stars orbiting it some 66 astronomical units away (known as Kepler-444 BC). A quintet of planets also orbits Kepler-444 A. All five worlds have radii between 0.4 and 0.7 Earth radius, and every one has an orbital period under 10 days.

image of the three stars in the Kepler-444 system
Typical observation of the central star Kepler-444 A and the binary pair Kepler-444 BC.
Adapted from Zhang et al. 2023

A team of astronomers led by Zhoujian Zhang (University of California, Santa Cruz) recently set about measuring the properties of the crowded system more precisely in several different ways. They used the High Resolution Spectrograph of the Hobby-Eberly Telescope at the McDonald Observatory in Texas to measure Kepler-444 A’s radial velocity. The star’s speed changes as it is pulled around by the other objects in the system. Zhang’s team also measured the relative radial velocities between the binary pair and the central star using the High Resolution Echelle Spectrometer at the W. M. Keck Observatory in Hawaii.

The gravitational pull of its companions causes Kepler-444 A to follow a wiggling path across the night sky. Measuring this changing position is known as astrometry. Zhang’s team conducted astrometric measurements of Kepler-444 A using Keck’s near-infrared imager (NIRC2).

EXPANDING PLANET-FORMING POTENTIAL

Putting all these pieces of the puzzle together, the team arrived at a deeper understanding of the Kepler-444 system and its history. Previous measurements of the system suggested that the binary swings in to within 5 astronomical units of Kepler-444 A. That would have truncated Kepler-444 A’s protoplanetary disk, severely depleting the amount of planet-forming material available. It wasn’t clear how five rocky planets could have formed there.

plot of observed and modeled on-sky separation between the central star and the binary pair.
Top panel: Observed (orange circles) and modeled (green lines) separations between Kepler-444 A and Kepler-444 BC. The black line shows the best-fitting model. Bottom panel: Observed values minus modeled values.
Adapted from Zhang et al. 2023

Now, based on their new measurements, Zhang’s team conclude that the Kepler-444 BC binary only gets within 23 astronomical units of Kepler-444 A. This wider separation would have led to a larger and more massive protoplanetary disk truncated to 8 astronomical units. The team calculate that there would have been 500 Earth masses’ worth of dust available from which to build planets. That compares to just 4 Earth masses of dust using previous estimates. Suddenly the presence of five planets is less perplexing.

As astronomers gain a greater understanding of exoplanets, it’s becoming clear that there’s more than one way to make a solar system.


Labels:

Comments

Post a Comment

Popular posts from this blog

Why did Homo sapiens outlast all other human species?

  From - Live Science By  Mindy Weisberger Edited by - Amal Udawatta Reproductions of skulls from a Neanderthal (left), Homo sapiens (middle) and Australopithecus afarensis (right)   (Image credit: WHPics, Paul Campbell, and Attie Gerber via Getty Images; collage by Marilyn Perkins) Modern humans ( Homo sapiens ) are the sole surviving representatives of the  human family tree , but we're the last sentence in an evolutionary story that began approximately 6 million years ago and spawned at least 18 species known collectively as hominins.  There were at least nine  Homo  species — including  H. sapiens  —  distributed around Africa, Europe and Asia by about 300,000 years ago, according to the Smithsonian's  National Museum of Nat ural History  in Washington, D.C. One by one, all except  H. sapiens  disappeared.  Neanderthals  and a  Homo  group known as the  Denisovans  lived alongside  H. sapiens  for thousands of years, and they even interbred, as evidenced by bits of their DN
Post a Comment
Read more

Jared Leto climbs Empire State Building

  By Steven McIntosh Entertainment reporter, Edited by Amal Udawatta IMAGE SOURCE, GETTY IMAGES Image caption, Leto said it was a "nice surprise" to see his mother through the window when he reached the 80th floor He's known for going to great lengths to win an Oscar - and now Jared Leto is going to great heights to promote his band's next tour. The actor and musician has become the first person to legally scale the 102-story Empire State Building. Leto, 51, climbed the outside of the New York landmark in a bright orange jumpsuit and using a rope and harness. He took on the challenge to promote the forthcoming world tour for his band Thirty Seconds To Mars. Leto told NBC's Today show:  "I was more excited than nervous to tell you the truth. But I have to be honest, it was very, very hard. It was a lot harder than I thought it would be. "Just the endurance that it took, the stamina that it took, and it was very sharp." The actor won an Oscar for his
Post a Comment
Read more

Humans have been speaking for a lot longer than we originally thought

       From -  Independent Magazine      By - David Keys      Edited  by - Amal Udawatta New research has pinpointed the likely time in  prehistory  when humans first began to speak. Analysis by British archaeologist Steven Mithen suggests that early humans first developed rudimentary  language  around 1.6 million years ago – somewhere in eastern or southern Africa. “Humanity’s development of the ability to speak was without doubt the key which made much of subsequent human physical and cultural  evolution  possible. That’s why dating the emergence of the earliest forms of language is so important,” said Dr Mithen, professor of early prehistory at the University of Reading. Until recently, most human evolution experts thought that humans only started speaking around 200,000 years ago. Professor Mithen’s new research, published this month, suggests that rudimentary human language is at least eight times older. His analysis is based on a detailed study of all the available archaeological
Post a Comment
Read more