According to some Christian outlooks we were made for another world. Perhaps, rather, we were made for this world to recreate, reclaim, redeem, and renew unto God's future aspiration by the power of His Spirit. - R.E. Slater
Secularization theory has been massively falsified. We don't live in an age of secularity. We live in an age of explosive, pervasive religiosity... an age of religious pluralism. - Peter L. Berger
Exploring the edge of life and faith in a post-everything world. - Todd Littleton
I don't need another reason to believe, your love is all around for me to see. – anon
Thou art our need; and in giving us more of thyself thou givest us all. - Khalil Gibran, Prayer XXIII
Be careful what you pretend to be. You become what you pretend to be. - Kurt Vonnegut
Religious beliefs, far from being primary, are often shaped and adjusted by our social goals. - Jim Forest
People, even more than things, need to be restored, renewed, revived, reclaimed, and redeemed; never throw out anyone. – anon
Certainly God's love has made fools of us all. - R.E. Slater
An apocalyptic Christian faith doesn't wait for Jesus to come, but for Jesus to become in our midst. - R.E. Slater
Christian belief in God begins with the cross and resurrection of Jesus, not with rational apologetics. - Eberhard Jüngel, Jürgen Moltmann
Our knowledge of God is through the 'I-Thou' encounter, not in finding God at the end of a syllogism or argument. There is a grave danger in any Christian treatment of God as an object. The God of Jesus Christ and Scripture is irreducibly subject and never made as an object, a force, a power, or a principle that can be manipulated. - Emil Brunner
Ehyeh Asher Ehyeh means "I will be that who I have yet to become." - God (Ex 3.14)
Our job is to love others without stopping to inquire whether or not they are worthy. - Thomas Merton
The church is God's world-changing social experiment of bringing unlikes and differents to the Eucharist/Communion table to share life with one another as a new kind of family. When this happens we show to the world what love, justice, peace, reconciliation, and life together is designed by God to be. The church is God's show-and-tell for the world to see how God wants us to live as a blended, global, polypluralistic family united with one will, by one Lord, and baptized by one Spirit. – anon
The cross that is planted at the heart of the history of the world cannot be uprooted. - Jacques Ellul
The Unity in whose loving presence the universe unfolds is inside each person as a call to welcome the stranger, protect animals and the earth, respect the dignity of each person, think new thoughts, and help bring about ecological civilizations. - John Cobb & Farhan A. Shah
If you board the wrong train it is of no use running along the corridors of the train in the other direction. - Dietrich Bonhoeffer
God's justice is restorative rather than punitive; His discipline is merciful rather than punishing; His power is made perfect in weakness; and His grace is sufficient for all. – anon
Our little [biblical] systems have their day; they have their day and cease to be. They are but broken lights of Thee, and Thou, O God art more than they. - Alfred Lord Tennyson

Tuesday, June 3, 2014

Scientific American - A Stellar Discovery on the Milky Way's Far Side


Five Cepheid-class stars (yellow dots at the top) were found beyond the most distant spiral arms of the
Milky Way, on the opposite side of the Solar System. Cepheids can be used as measurement beacons,
or 'standard candles', of cosmic distances. NASA/JPL-Caltech/R. Hurt, SSC-Caltech (base image);
Ariel Weiss (Cepheid positions)

A stellar discovery on the Milky Way's far side
http://www.nature.com/news/a-stellar-discovery-on-the-milky-way-s-far-side-1.15338

June 2, 2014

Five remarkable stars on the other side of our galaxy promise new insight into the outer reaches of our home turf.

A single Hubble Space Telescope image can capture scores of distant galaxies, but the one galaxy we'll never see from the outside is our own.

As a result, no one knows the Milky Way's exact size and shape. It took more than a century after the discovery of the first spiral in space before astronomers established that our galaxy is a spiral, too, and more years elapsed before they deduced that we inhabit a barred spiral — a type whose bright central region is elongated.

Now, for the first time, observers have detected five stars on the far side of the galaxy that serve as outstanding yardsticks, a feat which will divulge secrets about the Milky Way's terra incognita. "It's a beautiful piece of classic astronomy," says Leo Blitz, an astronomer at the University of California, Berkeley, who was not involved in the discovery.

The researchers, in South Africa and Japan, discovered five stars known as Cepheids shining on the opposite side of the Milky Way's disk, 72,000 to 99,000 light-years from Earth. All five stars lie behind the galactic center, which is in the constellation Sagittarius about 27,000 light-years from us.

Cepheids have starred in numerous astronomical breakthroughs because they reveal a crucial quantity: celestial distance. A Cepheid is a yellow supergiant — a star as warm as the sun but much more luminous — that periodically pulsates, expanding and contracting so that its light waxes and wanes. Just as a tuba resonates at a lower frequency and deeper pitch than the trumpet it dwarfs, so a large and luminous Cepheid takes longer to pulsate than a smaller, dimmer Cepheid. Thus, merely measuring a Cepheid's pulsation period indicates how much light the star emits. Comparing this luminosity with how bright the Cepheid looks reveals its distance from Earth — the farther the star, the fainter it appears.

The Cepheids' location initially suggested they had come from the nearby Sagittarius Dwarf Galaxy1 which the Milky Way's gravity is tearing apart. "We were quite surprised to find that these [stars] didn't have the right velocities for that," says Michael Feast, an astronomer at the University of Cape Town. Using the Southern African Large Telescope (SALT) the astronomers measured the stars' Doppler shifts at infrared wavelengths, which penetrate dust in the galaxy's disk. The velocities derived from the Doppler shifts indicated that all five Cepheids belong to our galaxy. The astronomers report their discovery in the May 15 issue of Nature2.

The stars are well above, and below, the galactic plane. Cepheids are always fairly young — born less than 130 million years ago — and young stars normally reside within just a few hundred light-years of the galactic plane. The five far-off Cepheids are 2,900 to 6,800 light-years above or below the plane, suggesting that the far side of the Milky Way's stellar disk is flared, like the wide end of a trumpet. This finding makes sense, however, because interstellar gas, which produces young stars, is also flared on the galaxy's outskirts. "It's exciting to see these young objects way over there," says Thomas Dame of the Harvard–Smithsonian Center for Astrophysics, not involved with the study, who uses radio waves from molecular gas to map spiral arms as their gas gives birth to new stars. "Ninety percent of what we know about the spiral structure of the galaxy comes from our side. We don't know much at all about the other side."

In 2011 Dame and his colleague Patrick Thaddeus traced a great spiral arm named Scutum–Centaurus across the Milky Way's far side, finding that the spiral arm rises several thousand light-years above the galactic plane there. Unfortunately, unlike Cepheids, these radio observations yield only crude distances, and Dame says the spiral map here may be as flawed as the maps navigators used during the age of Columbus. He notes that three of the Cepheids have similar positions, which suggests to him that they lie in the mighty Scutum–Centaurus Arm; but their distances place them beyond its location on the map, so the Scutum–Centaurus Arm may actually lie farther away than originally estimated. One Cepheid even shines beyond the edge of the stellar disk, hinting at another remote spiral feature on the galaxy's far side.

What's needed to resolve these matters? More Cepheids. "Five is a miserable few," Feast laments. But he says their discovery "opens up the possibility that big surveys, especially in the infrared, will throw up more stars like this and allow one to really investigate the structure of the galaxy out at these distances." In another decade we should have a better view of our galactic home.



More from Scientific American.



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