Astronomers Find Sun's Twin

space.com ^ | 01/07/04 | Tariq Malik

[KevinDavis]

ATLANTA - The Sun has a twin, astronomers announced Tuesday.

The solar doppelganger hits nearly identical marks in temperature, rotation and age. Planet hunters have it on their lists, but there’s no word yet whether carbon-based folks are looking back at their star’s twin, our own Sun.

18 Scorpii is in the constellation Scorpius, visible in the predawn sky to the south. Finding it requires completely dark skies and a map configured for your location.

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[KevinDavis]

Forget Mars, I say we should go to 18 Scorpii!

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[KevinDavis]

Space Ping! This is the space ping list! Let me know if you want on or off this list!

[LibWhacker]

Interesting, but it doesn't mean much in terms of our search for life. Take away the earth and the Solar System is a pretty bleak place.

[Paul C. Jesup]

18 Scorpii is in the constellation Scorpius, visible in the predawn sky to the south. Finding it requires completely dark skies and a map configured for your location.

Paging all FR Farscape fans.

Sorry, I could not help me. ;D

[TomServo]

I say we should go to 18 Scorpii!

lol! You first. Don't forget the sun block. ;-)

[martin_fierro]

Cool (Free!) Astronomy-related Software: Please FReepmail other suggestions

Celestia: A real-time space simulation that lets you experience our universe in three dimensions. Unlike most planetarium software, Celestia doesn't confine you to the surface of the Earth. You can travel throughout the solar system, to any of over 100,000 stars, or even beyond the galaxy. All travel in Celestia is seamless; the exponential zoom feature lets you explore space across a huge range of scales, from galaxy clusters down to spacecraft only a few meters across. A 'point-and-goto' interface makes it simple to navigate through the universe to the object you want to visit. Sky Screen Saver: Shows the sky above any location on Earth, including stars (from the Yale Bright Star Catalogue of more than 9000 stars to the 7th magnitude), the Moon in its correct phase and position in the sky, and the position of the Sun and all the planets in the sky. Outlines, boundaries, and names of constellations can be displayed, as well as names and Bayer/Flamsteed designations of stars brighter than a given threshold. A database of more than 500 deep-sky objects, including all the Messier objects and bright NGC objects can be plotted to a given magnitude. The ecliptic and celestial equator can be plotted, complete with co-ordinates. Home Planet: A comprehensive astronomy / space / satellite-tracking package for Microsoft Windows 95/98/Me and Windows NT 4.0/2000/XP and above. Selected features: An earth map, showing day and night regions, location of the Moon and current phase, and position of a selected earth satellite. Earth maps can be customised and extended.Hposition and phase data for the Sun and Moon. Panel showing positions of planets and a selected asteroid or comet, both geocentric and from the observer's location. A sky map, based on either the Yale Bright Star Catalogue or the 256,000 star SAO catalogue, including rendering of spectral types, planets, earth satellites, asteroids and comets. Databases of the orbital elements of 5632 asteroids and principal periodic comets are included, allowing selection of any for tracking. A telescope window which can be aimed by clicking in the sky map or telescope itself, by entering coordinates, or by selecting an object in the Object Catalogue. A horizon window which shows the view toward the horizon at any given azimuth. Object Catalogue allows archiving images, sounds, and tabular data about celestial objects. Orrery allows viewing the solar system, including a selected asteroid or comet, from any vantage point in space, in a variety of projections. Satellite tracking panel. Select an Earth satellite from a database of two-line elements, and see its current position and altitude. View Earth From panel allows you to view a texture-mapped image of the Earth as seen from the Sun, Moon, a selected Earth satellite, above the observing location, or the antisolar point. Satellite database selection allows maintenance of multiple lists of satellites, for example TV broadcast, ham radio, low orbit, etc. SETI@Home: A scientific experiment that uses Internet-connected computers in the Search for Extraterrestrial Intelligence (SETI). You can participate by running a free program that downloads and analyzes radio telescope data.

[TomServo]

Thanks Martin! Appreciated...

[martin_fierro]

Check out Celectia. It really is outstanding.

[TomServo]

I will....thanks again...

[petuniasevan]

From Solstation.com:

The Star

18 Scorpii is a yellow-orange main sequence dwarf star of spectral and luminosity type G1-5 V-Va. A little bigger and brighter than Sol, the star may have a mass similar to Sol's -- an inferred mass of 1.01 +/- 0.03 Solar-mass (Ryan et al, 2004; Guinan et al, 1999; and Porto de Mello and da Silva, 1997), 1.02 to 1.03 times its diameter (Ryan et al, 2004; and Johnson and Wright, 1983, page 685), and 1.05 times its luminosity. It may be 105 to to 112 percent as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Porto de Mello and da Silva, 1997; and Cayrel de Strobel et al, 1991, 300).

A team of astronomers studying 18 Scorpii announced on January 6, 2004 -- at the 203rd Meeting of the American Astronomical Society -- that the star's surface temperature is 5,789 degrees Kelvin, slightly hotter than Sol's 5,777 degrees. The star takes 23 days to rotate, slightly faster than Sol's rotational period of 25.4 days. A middle-aged star that is slightly younger than Sol's 4.56 billion years, 18 Scorpii is now thought to be around 4.2 billion years old (rather than the previous estimate of 4.7 +/- 0.8 billion years estimated in Guinan et al, 1999).

Some astronomers have regard 18 Scorpii as the nearest "Solar twin" (space.com; Ryan et al, 2004; and Porto de Mello and da Silva, 1997). Its starspot cycle lasts nine to 13 years while Sol's waxes and wanes every 11 years (Ryan et al, 2004). Observations through 2000, however, indicate that 18 Scorpii has a well-defined activity cycle which reached an apparent minimum in 1998 then showed a rapid rise through 2000. A comparison with contemporaneous Solar data using the same instrument suggests that 18 Scorpii's activity cycle may be of greater amplitude than Sol's and that its overall chromospheric activity level is noticeably greater than Sol's. Hence, this otherwise, "excellent solar photometric twin therefore may be a less perfect spectroscopic twin" (Hall and Lockwood, 2000). 18 Scorpii has been given the variable star designations: CSV 101566, NSV 7577, and SV ZI 1223. Other useful catalogue numbers and designations for the star include: 18 Sco, HR 6060, Gl 616, Hip 79672, HD 146233, BD-07 4242, SAO 141066, LHS 3172, LTT 6482, LFT 1259, and LPM 594.

The star is part of a survey of Sol-type stars in the local galactic neighborhood, by which astronomers hope to understand better Sol's past and future evolution. Young stars were observed to be 30 percent dimmer in brightness. Since they spin much faster, however, young stars were also found to have strong magnetic fields which apparently led to huge stellar flares that erupted one or twice a day with abundant emission of x-rays and ultraviolet light. Older stars appeared to have become quieter as they age, as the oldest emit only about a fifth as much x-ray energy as Sol before exhausting core hydrogen fusion into expanding into red giants.

[petuniasevan]

I say we should go to 18 Scorpii!

lol! You first. Don't forget the sun block. ;-)

Avoid the exposure! Go at night!!! ;-D

I say we should go to 18 Scorpii!

lol! You first. Don't forget the sun block. ;-)

[TomServo]

Avoid the exposure! Go at night!!! ;-D

Heh heh - an oldie but a goodie...

[BenLurkin]

"18 Scorpii, sits about 47.5 light-years away "

Practically next door in galactic terms. Any word yet on planets? Even the presence of gas giants like Jupiter could signal a similar solar system structure to ours.

A "Generation Ship" could be there in say, three hundred to five hundred years which really would not be that long a time to start a human presence in a new solar system

[BenLurkin]

Not a problem - we'll land at night.

[Kieri]

Paging all FR Farscape fans. Sorry, I could not help me. ;D

No apology necessary! I'm sure good ol' Scorpy is there, dancing in his Mambo shirt, slugging down lime shooters with John Crichton, celebrating their resurrection in the Farscape miniseries now in production!

[genghis]

if you enjoyed this thread- you will enjoy an amazing book
"the rare earth" by brownlee and war
2 profs at u of wash.
also www.funckyscience.net
for the rejoinder.

[mikrofon]

18 Scorpii seems to be a rather stilted designation for Sol's twin -- maybe they should name it Murray...

[sigSEGV]

You can bet there will be a lot of planet hunters checking out the wobbles in that star. One would have to think that something so similar to our own would have to have a much similar initial environment.

Just think. If there were an Earth-like planet around it, we could be taking pictures of its continents within the next 20 years.

[BenLurkin]

We're thinking along similar lines here, but how do we get there in twenty years when it is 47 light years away?