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Posts Tagged ‘Deneb’

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.

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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.

06/26/2017 – Ephemeris – Latest sunset and the apparent positions of the Summer Triangle stars

June 26, 2017 1 comment

Ephemeris for Monday, June 26th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:31, and it will rise tomorrow at 5:59. The Moon, 3 days past new, will set at 11:40 this evening.

Tonight we have the latest sunset of the year. From now on until December sunsets will become earlier. Other than the sunrise and sunset numbers, we’ll begin to notice it for real in a few weeks. At first that realization strikes me a sad note that summer is beginning to end. However the astronomer in me realizes that means more night-time hours, and that the summer Milky Way is coming. Of the three bright stars of the Summer Triangle overhead and in the east, two of its stars are in the milky band. They are Deneb to the north and Altair to the south. Vega, closest to the zenith is not in the band. Actually all the stars we see with the naked eye or small telescopes belong to the Milky Way galaxy.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The constellations Lyra, Cygnus and Aquila

Looking at the stars of the Summer Triangle and their location in and near the Milky Way band. Created using Stellarium.

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.

074/26/2016 – Ephemeris – The flying swan and Northern Cross

July 26, 2016 Comments off

Ephemeris for Tuesday, July 26th.  The Sun rises at 6:22.  It’ll be up for 14 hours and 52 minutes, setting at 9:15.  The Moon, at last quarter today, will rise at 1:09 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.  It takes a telescope, but Alberio splits into a beautiful blue and gold binary star.

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

Addendum

CygnusTheSwan Created using Stellarium.

Cygnus the Swan Created using Stellarium.

06/23/2016 – Ephemeris – Tis the season to view the Summer Triangle

June 23, 2016 Comments off

Ephemeris for Thursday, June 23rd.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58.  The Moon, 3 days past full, will rise at 11:43 this evening.

Now that summer is here, the asterism or informal constellation called the Summer Triangle can be seen 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 its is by far the most distant of the three.  The third star of the Summer Triangle is seen farther below and right of Vega.  It is Altair in Aquila the eagle, and the closest.  Altair is 16.7 light years away, Vega is 25 light years while Deneb may be a whopping 2600 light years away.   With a light year at 6 trillion miles.  That’s mind boggling to think in miles at least.

Times 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.

11/20/2015 – Ephemeris – Finding the bright stars of November

November 20, 2015 Comments off

Ephemeris for Friday, November 20th.  The Sun will rise at 7:46.  It’ll be up for 9 hours and 24 minutes, setting at 5:10.   The Moon, 1 day past first quarter, will set at 2:17 tomorrow morning.

The Moon is beginning to brighten up the sky making constellation spotting somewhat difficult, so I thought we’d look for the brightest stars.  High in the west are the three stars of the Summer Triangle.  At the bottom in the southwest is Altair, the first of these to set.  A bit north of west the brightest, Vega.  Highest in the west is Deneb, which won’t officially set for those Interlochen northward.  Low in the south is the loneliest star Fomalhaut.  In the northeast is the winter star Capella, which also doesn’t set for the IPR listener area, but spends summer nights hiding behind hills and trees in the north.  Low in the east is the last of our bright stars, Aldebaran in Taurus the bull, which will be playing hide and seek with the Moon next week.

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

Addendum

Autumn bright stars

The bright first magnitude stars of autumn shown for 8 p.m. November 20, 2015. If you are closer to your time meridian, we’re 43 minutes behind ours, you will see two more bright stars in the east: Red Betelgeuse and blue-white Rigel. Created using Stellarium.