The Fox / The Little Fox
Vulpecula is a small, faint constellation in the northern hemisphere. It is unusual in that it is not one of the original 48 constellations created by 2nd century astronomer Ptolemy even though the pattern of stars were easily visible to him and other ancient Greeks and Romans.
The constellation as we know it today was created by Johannes Hevelius. He included it in his influential 56 page star atlas Firmamentum Sobiescianum that was published posthumously in 1690. Originally it was known as Vulpecula cum ansere (the little fox with the goose) or Vulpecula et Anser (the little fox and the goose). In his original illustration, Hevelius depicts an unfortunate goose carried in the jaws of a fox. Later the constellation was divided into two separate parts, Vulpecula and Anser and then remerged, this time for keeps, into a single entity by the International Astronomical Union (IAU). Renamed as just Vulpecula, the only remnant of the goose is the name of the constellations brightest star, Anser (a Vul).
Locating the area of the sky where Vulpecula lies is easy, it is wedged between the constellations of Cygnus and Sagitta with the western half located roughly in the middle of the famous Summer triangle (an asterism consisting of the bright stars Deneb, Vega and Altair).
At 288 square degrees, Vulpecula is the 55th largest constellation in the sky.
Anser (a Vul) – at mag 4.44 is the brightest star in the constellation. It is an M type red giant star located 297 light-years from Earth. Together with orange giant star 8 Vul (mag. 5.82), Anser forms a nice double, easily resolvable in 10x50 binoculars, with a separation of 427 arc seconds and a PA angle of 28.
However it is just a chance alignment, 8 Vul is believed to lie nearly 200 light-years more distant than Anser.
T Vulpeculae – is a Delta Cephei type variable star located 1672 light-years from Earth. It varies between mag. 5.41 and 6.09 over a period of 4.44 days.
PSR B1919+21 In July 1967, the first pulsar, PSR B1919+21 (original designation CP 1919), was discovered in Vulpecula by Jocelyn Bell and Antony Hewish in Cambridge, England. Initially, these strange pulsating signals were humorously named as Little Green Men 1, an obvious reference to some sort of extraterrestrial nature, until researchers Thomas Gold and Fred Hoyle correctly identified these signals as rapidly rotating neutron stars with strong magnetic fields.
PSR B1919+21 has a rotation period of 1.3373 seconds and is located 2283 light-years from Earth.
For deep sky observers, Vulpecula contains one of the skies finest planetary nebulae, M27 The Dumbbell Nebula, a famous coathanger shaped open cluster and a number of other faint open clusters.
M27 (NGC 6853) – Dumbbell Nebula is a famous showstopper must see planetary nebula. At visual mag. 7.4 it is the second brightest planetary nebula with only mag. 7.3 The Helix Nebula (NGC 7293) more luminous. Observationally, the Dumbbell Nebula is smaller than the Helix Nebula, has a much higher surface brightness and hence easier to observe. It is visible in all types of optical instrument.
A pair of 10x50 binoculars reveals M27 as a hazy small patch located in a circular grouping of bright stars. Larger 20x80 binoculars or a small 100mm (4-inch) telescope show M27 more clearly with the centre region slightly brighter but not distinct from the outer regions. In a larger 200mm (8-inch) telescope both sides of the nebula appear dimmer than the central region, giving the nebula its famed dumbbell or apple core shape. A large amount of surface detail is detectable with both direct and averted vision. Larger aperture telescopes still show more subtle details.
M27 measures 8x6 arc minutes and is located 1360 light-years from Earth.
Open Cluster and Emission Nebula
NGC 6823/6820 - NGC 6823 is a mag. 7.1 open cluster of about 40 stars covering a diameter of 12 arc minutes. The cluster is surrounded by a larger but fainter emission nebula, NGC 6820.
In 10x50 binoculars, NGC 6823 is visible as a very faint glow. Larger 20x80 binoculars show the elongated shape of the cluster with the brightest stars resolvable. A medium size telescope of 200mm (8-inches) aperture brings out the oval shape, with about twenty or so stars visible. Averted vision reveals more faint stars in the centre of the cluster with the brightest stars at the core appearing diamond or kite shaped.
The emission nebula NGC 6820 is a much more difficult object to observe. A 200mm (8-inch) telescope is the minimum size recommended; NGC 6820 appears as a faint glow surrounding NGC 6823 that appears more obvious when viewed using averted vision and/or with a UHC filter. Larger telescopes bring out more subtle details.
The best views of NGC 6820 are reserved for photographers and imagers. Here the nebula is seen in full glory and blushing colour with its most striking feature, a larger pillar of gas and dust on the eastern side of the nebula, similar to one of the famous pillars in the Hubble Telescopes Eagle Nebula “Pillars of Creation” photograph.
Open cluster NGC 6823 is about 20 light-years across and lies about 6000 light-years distance.
Brocchi's Cluster (Collinder 399) – The Coathanger
is a random grouping of stars near the Vulpecula border with Sagitta that is best viewed through binoculars or a small / wide field telescope. The brightest 10 stars of the asterism are between 5th and 7th mag. and are arranged in the shape of an obvious Coathanger. Six of the ten stars form an almost straight line with the remaining four shaped like a hook hanging off to the south.
At a dark site, the cluster is just about visible to the naked eye as an unresolved haze, although binoculars or small sized telescopes are required to show the Coathanger shape. Through 10x50 binoculars the cluster is spectacular, spanning about 1 degree in diameter with the main stars easily visible along with a splattering of fainter stars. Equally striking views are obtained in small or wide field telescopes of the order of 60-100mm (2.4 – 4 inch). With larger apertures the Coathanger effect is slightly lost due to the decreased field of view, but still interesting to look at.
The Coathanger was first noted before 964 by the Persian astronomer Al Sufi, and described in his Book of Fixed Stars in 964. Later in the 17th century, Italian astronomer Hodierna independently rediscovered it and was catalogued by American amateur astronomer Brocchi in the 1920s and by Swedish astronomer Collinder in 1931.
Stock 1 - A large binocular cluster covering an area of 1 1/3 degrees, over twice the size of the full moon. At mag. 5.3 Stock 1 is theoretically visible to the naked under dark skies, but difficult due to its scattered nature. However, it is a nice object that is the largest of all Vulpecula open clusters and in total may contain up to 40 stars.
NGC 6882/6885 - Open clusters NGC 6882 and NGC 6885 may or may not be the same item, there is much debate regarding this. William Herschel discovered these open clusters on successive nights and gave almost identical descriptions for both. General consensus is that NGC 6882 and NGC 6885 are identical. To complicate the story further, Per Collinder included a small scattering of stars to the NW edge of NGC 6882/6885 as number (Cr) 416 in his catalogue of open clusters.
NGC 6882/6885 is grouped around mag 5.9 star 20 Vul and consists of up to 40 stars. The rough diameter of the cluster is about 20 arc minutes with more compact cluster Cr 416 located at the NW corner (diameter 8 arc minutes). The magnitude of the cluster NGC 6882/6885 is 5.5 with Cr 416 fainter at mag. 8.1. All in all, the whole area is a nice grouping of stars centred on bright stand out star 20 Vul. Binoculars show the main stars and give a feeling for the area, medium and large size telescopes reveal more. To some it appears as just one star grouping. What do you think?
NGC 6940 is a nice open cluster easily visible in 10x50 binoculars as an elliptical haze, just beyond resolution, surrounded by a few foreground stars. Larger binoculars or a small 80mm (3.1 inch) telescope resolve few stars, however when viewed through a medium size 200mm (8-inch) telescope the cluster is rewarding. With a size of 25 arc minutes, almost as large as the full moon, it fills the eyepiece with dozens of stars visible. Averted vision reveals fainter stars through the cluster. Larger telescopes reveal many more.
The cluster’s distance is about 2500 light-years and contains about 60 stars. It is not a young cluster, with an estimated age of 800 million years.
NGC 6834 is a compact mag. 7.8 open cluster about 7,000 light-years from Earth located at the Cygnus / Vulpecula border. The cluster is visible in a 100mm (4-inch) small telescope with best views reserved for larger instruments. In a 200mm (8-inch) telescope, NGC 6834 appears as a nice, small compressed, rich, wedge shaped open cluster with a V shape grouping of bright stars at the centre.
NGC 6834 has a diameter of 6 arc minutes with up to 50 stars brighter than mag. 15. The estimated age of the cluster is 65 million years.
NGC 6830 - at mag. 7.9, NGC 6830 is a loose cluster of at least 20 stars covering an area of 10 arc minutes. It is visible in binoculars as an unresolved haze; a 200mm (8-inch) scope easily shows the brightest stars that are arranged in a distinct “X” shape. Larger telescopes show many more faint stars within the cluster.
NGC 6802 - When observing the Coathanger cluster with a medium / large size telescope, look to the eastern edge and you should be able to notice the faint mag. 8.8 open cluster NGC 6802. It is easily visible in a 200mm (8-inch) telescope appearing as a line of about 10 faint stars extending in a north-south direction. Using averted vision, the cluster appears more pronounced with fainter stars visible. With a large 350mm (14-inch) telescope, the oblong nature of the cluster is more prominent and more stars are visible.
NGC 6802 is 5 arc minutes in diameter and contains up to 50 stars.
Vulpecula Star Data Table
|Henry Draper Catalogue (HD)||Hipparcos Catalogue (HIP)||Bayer||Flamsteed||Name||RA (J2000)||Dec (J2000)||Visual Mag.||Rotation Period (secs)||Var.||Var. Mag. Range||Period (days)||Double||Sep. (arc secs)||PA (degs)||Mag. Primary / Sec|
|183439||95771||Alpha Vul||6||Anser||19h 28m 42s||+24d 39m 55s||4.44||---||---||---||---||Y||427||28||4.61 / 5.82|
|198726||102949||---||---||T Vul||20h 51m 28s||+28d 15m 02s||5.66||---||Y||5.41->6.09||4.44||---||---||---||---|
|---||---||---||---||PSR B1919+21||19h 21m 45s||+21d 53m 02s||---||1.3373||---||---||---||---||---||---||---|
Vulpecula Deep Sky Data Table
|Messier||NGC||Caldwell||Collinder||Stock||Name||Type||RA (J2000)||Dec (J2000)||Visual Magnitude||Apparent Size||Distance (light-years)||Actual Size (light-years)||Number of Stars|
|27||6853||---||---||---||Dumbbell Nebula||Planetary Nebula||19h 59m 36s||+22d 43m 17s||7.4||8' x 6'||1360||3.2 x 2.4||---|
|---||6823||---||405||---||---||Open Cluster||19h 43m 10s||+23d 18m 00s||7.1||12'||6000||20||40|
|---||6820||---||404||---||---||Emission Nebula||19h 42m 28s||+23d 05m 17s||10.0||40'||6000||70||---|
|---||---||---||399||---||Coathanger||Open Cluster||19h 25m 24s||+20d 11m 00s||3.6||60'||420||7.5||40|
|---||---||---||---||1||---||Open Cluster||19h 35m 48s||+25d 13m 00s||5.3||80'||1050||24||40|
|---||6882 / 6885||37||417||---||---||Open Cluster||20h 11m 56s||+26d 29m 20s||5.5||20'||2000||12||40|
|---||---||---||416||---||---||Open Cluster||20h 11m 35s||+26d 32m 04s||8.1||8'||2000||4.5||15|
|---||6940||---||424||---||---||Open Cluster||20h 34m 27s||+28d 16m 58s||6.3||25'||2510||18||60|
|---||6834||---||407||---||---||Open Cluster||19h 52m 13s||+29d 24m 29s||7.8||6'||7002||12||50|
|---||6830||---||406||---||---||Open Cluster||19h 50m 59s||+23d 06m 00s||7.9||10'||5340||16||20|
|---||6802||---||400||---||---||Open Cluster||19h 30m 35s||+20d 15m 39s||8.8||5'||345||0.5||50|