Jan 3, 2018

There may be an ordinary explanation for this mysterious star

This illustration depicts dust orbiting Tabby's Star. Illustration: NASA/JPL-Caltech

Several theories surround what is known as the "most mysterious star in the universe" — one in the Milky Way that is slightly bigger than our Sun and whose sporadic dimming and brightening puzzles scientists.

New data, published Wednesday in The Astrophysical Journal Letters, suggests the flickering is likely caused by a cloud of small dust particles — and not an alien megastructure orbiting the star, as some researchers hypothesized.

Their methodology: The scientists observed "Tabby's Star," nicknamed after Louisiana State University astronomer Tabetha Boyajian who led the study, through the Las Cumbres Observatory from March 2016 to December 2017, during which the star's light dipped four times.

Their findings, detailed in The Atlantic: The dimming they observed was much deeper at blue wavelengths than at red wavelengths, meaning that the object blocking the star was not opaque (an opaque object would block both colors in equal measure). That discovery led Boyajian's team to the conclusion that cosmic dust particles "just big enough to stick inside the star's orbit, but too small to block light in all wavelengths" are responsible.

Key quote: "Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure," Boyajian told The Atlantic.

Go deeper

Zuckerberg says Trump’s “shooting” tweet didn’t violate Facebook’s rules

Mark Zuckerberg at the 56th Munich Security Conference in Munich, Germany on February 15. Photo: Abdulhamid Hosbas/Anadolu Agency via Getty Images

Facebook did not remove President Trump's threat to send the National Guard to Minneapolis because the company's policy on inciting violence allows discussion on state use of force, CEO Mark Zuckerberg explained in a post on Friday.

The big picture: Zuckerberg's statement comes on the heels of leaked internal criticism from Facebook employees over how the company handled Trump's posts about the Minneapolis protests and his unsubstantiated claims on mail-in ballots — both of which Twitter has now taken action on.

Updated 22 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 7:30 p.m. ET: 5,916,464— Total deaths: 364,357 — Total recoveries — 2,468,634Map.
  2. U.S.: Total confirmed cases as of 7:30 p.m. ET: 1,744,258 — Total deaths: 102,709 — Total recoveries: 406,446 — Total tested: 16,099,515Map.
  3. Public health: Hydroxychloroquine prescription fills exploded in March —How the U.S. might distribute a vaccine.
  4. 2020: North Carolina asks RNC if convention will honor Trump's wish for no masks or social distancing.
  5. Business: Fed chair Powell says coronavirus is "great increaser" of income inequality.
  6. 1 sports thing: NCAA outlines plan to get athletes back to campus.

Trump says he spoke with George Floyd's family

President Trump in the Rose Garden on May 29. Photo: Win McNamee/Getty Images

President Trump told reporters on Friday that he had spoken with the family of George Floyd, a black resident of Minneapolis who died after a police officer knelt on his neck on Monday.

Driving the news: Former Vice President Joe Biden said via livestream a few hours earlier that he, too, had spoken with Floyd's family. The presumptive Democratic presidential nominee implored white Americans to consider systemic injustices against African Americans more broadly, Axios' Alexi McCammond reports.