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Prototype variable star has a previously unknown companion

The uncertainty of science: The star that gave its name to the class of variable stars called Cepheid variables — used by astronomers to measure distances to nearby galaxies — has after more than 200 years of study been suddenly found to be a binary system.

Delta Cephei, prototype of the cepheids, which has given its name to all similar variable stars, was discovered 230 years ago by the English astronomer John Goodricke. Since the early 20th century, scientists have been interested in measuring cosmic distances using a relationship between these stars’ periods of pulsation and their luminosities (intrinsic brightness), discovered by the American Henrietta Leavitt. Today, researchers from the Astronomical Observatory of UNIGE, Johns Hopkins University and the ESA show that Delta Cephei is, in fact, a double star, made up of a cepheid-type variable star and a companion that had thus far escaped detection, probably because of its low luminosity. Yet, pairs of stars, called binaries, complicate the calibration of the period-luminosity relationship, and can bias the measurement of distances. This is a surprising discovery, since Delta Cephei is one of the most studied stars, of which scientists thought they knew almost everything. [emphasis mine]

This discovery illustrates the shaky foundation of a great deal of astronomical research. The presence of a companion is an additional variable that could very significantly skew the relationship between the stars’ pulses and its luminosity, thus making the use of this data to determine distance much less reliable. This in turn could have a significant effect on the present estimate of the expansion rate of the universe, which in turn could have a significant effect on the theories of dark energy. Moreover, if the past distance estimates to many objects are wrong than what we know about those objects is far less certain.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

 
Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

One comment

  • LocalFluff

    This is phantastic. Now an astronomer doesn’t even know the distance between his head and his a**! Theoretical astrophysicists have since long demanded that we stop looking up, so that they get time to clean up the math of what is known by now. (Well, they dream about that happening at night, when the real astronomers are actually working to create more problems for them).

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