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07/17/2018 – Ephemeris – Finding Cygnus the swan

July 17, 2018 Leave a comment

Ephemeris for Tuesday, July 17th. Today the Sun will be up for 15 hours and 10 minutes, setting at 9:24, and it will rise tomorrow at 6:14. The Moon, 2 days before first quarter, will set at 12:32 tomorrow morning

High in the east northeast as it gets dark flies the constellation of Cygnus the swan. This constellation is also known as the Northern Cross. The cross is seen lying on its side with the bright star Deneb at the head of the cross to the left. The rest of the cross is delineated in the stars to the right. As a swan, Deneb is the tail, the stars of the crosspiece of the cross are the leading edges of wings as Cygnus flies south through the Milky Way. There are faint stars that also define the tips and trailing edges of its wings. It is a very good portrayal of a flying swan, like the mute swans we see on the wing. In Cygnus we are looking in the direction that the Sun and the Earth are traveling as we orbit the center of the Milky Way.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Cygnus finder animation

Animated Cygnus finder chart. Included also are, beside Deneb, the other stars of the Summer Triangle: Vega and Altair and their constellations Lyra the harp and Aquila. See if you can find them. Created using Stellarium.

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5/15/2018 – Ephemeris – Two thirds thru spring

May 15, 2018 Comments off

Ephemeris for Tuesday, May 15th. Today the Sun will be up for 14 hours and 49 minutes, setting at 9:04, and it will rise tomorrow at 6:13. The Moon is new today, and won’t be visible.

Here we are at the middle of May, nearly two-thirds through spring and in the west only a few winter stars remain. Castor and Pollux of Gemini are horizontal in the west, Procyon the Little Dog Star is below and left of them, Capella in Auriga is in the northwest, but for most of the IPR listening area it will never quite set. At 10:30 Betelgeuse in Orion the hunter will be setting, chased from the skies by Scorpius the scorpion, which is rising in the southeast. In one story it is the sting of this scorpion that killed him. Already at that time two-thirds of the stars of the summer Triangle are up. Bright Vega in Lyra the harp, and Deneb in Cygnus the swan. The Big Dipper reigns overhead as spring is in full bloom.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Goodbye winter, hello summer

The sky dome for 10:30 p.m. May 15, 2018 showing the stars and constellations. It may not work for any latitude or time, but it works for our location, near 45 degrees north. Created using Stellarium.

09/19/2017 – Ephemeris – The Great Rift

September 19, 2017 1 comment

Ephemeris for Tuesday, September 19th. The Sun will rise at 7:26. It’ll be up for 12 hours and 18 minutes, setting at 7:45. The Moon, 1 day before new, will rise at 7:43 tomorrow morning.

High overhead the Milky Way is seen passing through the Summer Triangle of three bright stars. Here we find the Milky Way split into two sections. The split starts in the constellation of Cygnus the Swan or Northern Cross very high in the east. The western part of the Milky Way ends southwest of the Aquila the eagle. This dark dividing feature is called the Great Rift. Despite the lack of stars seen there, it doesn’t mean that there are fewer stars there than in the brighter patches of the Milky Way. The rift is a great dark cloud that obscures the light of the stars behind it. Sometimes binoculars can be used to find the edges of the clouds of the rift, as stars numbers drop off suddenly. This is especially easy to spot in Aquila the eagle.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Great Rift in the Milky Way. Created using Stellarium.

The Great Rift in the Milky Way. Created using Stellarium.

07/14/2017 – Ephemeris – Constellations of the Summer Triangle II: Cygnus the swan

July 14, 2017 1 comment

Ephemeris for Friday, July 14th. Today the Sun will be up for 15 hours and 14 minutes, setting at 9:25, and it will rise tomorrow at 6:11. The Moon, 2 days before last quarter, will rise at 12:32 tomorrow morning.

Fairly high in the east at 11 p.m. Is the constellation of Cygnus the swan, flying south through the Milky Way. It is also called the Northern Cross. At the left, the tail of the swan or the head of the cross is the bright star Deneb, one of the stars of the Summer Triangle. The next star right is Sadr the intersection of the body and the wings of the swan seen in flight, or the intersection of the two pieces of the cross. There are two or three stars farther to the right that delineate the swan’s long neck or upright of the cross, that ends with the star Alberio in the beak of the swan or foot of the cross. The crosspiece of the cross extends to the stars on either side of the intersection star Sadr, while the swan’s wings extend to a couple more stars each.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Summer Triangle July 5, 2012 at 11 p.m. Created using Stellaruim and The Gimp.

The Summer Triangle. Created using Stellarium and The Gimp.

Cygnus finder animation

Animated Cygnus finder chart. Created using Stellarium.

In mythology Cygnus was the form Zeus took in the Leda and the swan affair.  Out of that union was born Pollux of Gemini fame.  His half-brother and twin Castor was fathered by a mere mortal.  Go here for their story.

Alberio is the star that shows in Cygnus’ eye.  In telescopes of even low power Alberio shows as a binary star whose components are distinctly and beautiful blue and gold.  Binoculars are not quite powerful enough to split these two.

07/10/2017 – Ephemeris – Deneb, a super bright star

July 10, 2017 1 comment

Ephemeris for Monday, July 10th. Today the Sun will be up for 15 hours and 20 minutes, setting at 9:27, and it will rise tomorrow at 6:08. The Moon, 1 day past full, will rise at 10:24 this evening.

This evening when it gets dark the bright star Deneb in Cygnus the swan will be high in the east-northeast. Deneb is the dimmest star of the summer triangle. Of the other stars of the triangle, Vega is higher in the east, while Altair is lower in the southeast. While Deneb’s apparent magnitude, or brightness as seen from Earth, makes it the dimmest of the three bright stars, Deneb’s vast distance of possibly 1,400 light years* makes it over 50 times the distance of Vega. If brought as close as Vega, Deneb would be as bright at least as the quarter moon. It is possibly as bright as 200 thousand Suns; and a huge star, possibly as large in diameter as the orbit of the Earth. For all this it is only 20 to 25 times the mass of the sun.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

* Deneb’s distance is not well known.  Over the years with the Ephemeris program and this blog I’ve given various distances to the star.  Having no companion and being beyond the distance where trigonometric parallax is used, at least from the ground, makes distance measurement difficult.  Hipparcos  satellite measurements give a distance about twice as great.  Estimates of the true brightness of a star are based on its known distance.  An error in distance by a factor of two gives an error in terms of intrinsic luminosity by a factor of 4, due to the inverse square law of brightness with distance.

Addendum

The constellations Lyra, Cygnus and Aquila

Deneb with the other stars and constellations in the Summer Triangle. Created using Stellarium.

Deneb & North American Nebula

One of my old photographs of Deneb and the North American Nebula digitized from a slide. Deneb’s ultraviolet emissions cause the North American and unnamed here Pelican Nebulae to glow.  The red color is due to hydrogen.

06/22/2017 – Ephemeris – Now that it’s summer, lets check out the Summer Triangle

June 22, 2017 1 comment

Ephemeris for Thursday, June 22nd. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 1 day before new, will rise at 5:45 tomorrow morning.

We’re a day into summer, and the asterism or informal constellation called the Summer Triangle can be seen rising in the east as it gets dark. Highest of the three bright stars is Vega in the constellation Lyra the harp, whose body is seen in a narrow parallelogram nearby. The second star of the triangle is Deneb lower and left of Vega, It appears dimmer than Vega because it is by far the most distant of the three. The third star of the Summer Triangle is seen farther below and a right of Vega. It is Altair in Aquila the eagle, and the closest. Altair is 16.5 light years away, Vega is 27 light years while Deneb may be a whopping 2600 light years away. One light year is 6 trillion miles (9 trillion km).

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Summer Triangle July 5, 2012 at 11 p.m. Created using Stellaruim and The Gimp.

The Summer Triangle. Created using Stellarium and The Gimp.

01/13/2017 – Ephemeris – Perhaps we’ll see a nova in 5 years, 2022

January 13, 2017 Comments off

Jan 13.  This is Bob Moler with Ephemeris for Friday, January 13th.  The Sun will rise at 8:16.  It’ll be up for 9 hours and 9 minutes, setting at 5:26.  The Moon, 1 day past full, will rise at 7:12 this evening.

Professor Larry Molnar from Calvin College in my home town of Grand Rapids and his students discovered that a star, [KIC 9832227,] that was monitored by the Kepler exoplanet finding satellite in the northern constellation of Cygnus the Swan may explode in about 5 years.  The star is actually two so close that they share their outer atmospheres, someone described it as two peanuts in one shell.  The two orbit each other in 11 hours now, and the period is shortening at an accelerated rate as the two approach each other.  Astronomers think that it will repeat the fate of a star that exploded in 2008 in the constellation of Scorpius.  Such explosions, when seen are called Novae.  A Nova like this could make the star briefly 10,000 times brighter than it originally was. [Current magnitude is 12, which is visible in moderate sized (6″ or 150 mm) diameter telescopes.  10,000 times brighter equals a 10 magnitude bump, which would make the star 2nd magnitude.  Magnitudes are like golf scores the lower the magnitude the brighter the object.  Blame Hipparchus.]

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Note:  The text in brackets omitted in the broadcast.

Addendum

 

Finder Chart

Finder Chart for KIC 9832227. It’s in the red bulls eye. Credit: Calvin College.

The position of KIC 9832227 is circumpolar or nearly so for northern Michigan.  So it’s up all or most of the 24 hour day, so no matter the time of year this baby blows, we should be able to see it.

What the star(s) may look like

Two computer generated views of KIC 9832227. The large star is about twice the Sun’s diameter, while the smaller star is a bit less than the Sun’s size. Credit: Calvin College.

For more information click here:  https://calvin.edu/news/archive/astronomy-prof-student-predict-explosion-that-will-change-the-night-sky.