Hanny's Voorwerp
Encyclopedia
(ˈhɑːn.nis ˈvoʊr.wærp), Dutch
for Hanny's object, is an astronomical object of unknown nature. It was discovered in 2007 by Dutch
school teacher Hanny van Arkel, while she was participating as an amateur volunteer in the Galaxy Zoo
project. Photographically, it appears as a bright blob close to spiral galaxy
IC 2497
in the constellation Leo Minor
.
galaxy and has a huge central hole over 16,000 light years across. In the image, the voorwerp is colored green, a false color that is standardly used to represent the presence of several luminous emission lines of glowing oxygen. It has been shown to be at the same distance from Earth
as the adjacent galaxy, both about 650 million light-year
s away.
Star birth is occurring in the region of the object that faces IC 2497. Radio observations indicate that this is due to an outflow of gas arising from the IC 2497's core which is interacting with a small region of Hanny's Voorwerp to collapse and form stars. The youngest stars are several million years old.
A picture of the object appeared on the Astronomy Picture of the Day
website in data taken by Dan Smith (Liverpool John Moores University
), Peter Herbert (University of Hertfordshire
) and Chris Lintott (University of Oxford
) on the 2.5 metre Isaac Newton Telescope
.
event that occurred in the center of a nearby galaxy, IC 2497
about 100,000 years previously. The quasar event is thought to have stimulated the bright emission that characterizes the voorwerp. The quasar
may have switched off in the last 200,000 years, and is not visible in the available images.
One possible explanation for the missing light-source is that illumination from the assumed quasar
was a transient phenomenon
. In this case, its effects on the voorwerp would be still visible because of the distance of several tens of thousands of light years between the voorwerp and the quasar
in the nearby galaxy: the voorwerp would show a "light echo
" or "ghost image," of events that are older than those currently seen in the galaxy.
On 17 June 2010, a group of researchers at the European Very Long Baseline Interferometry Network (EVN) and the UK’s Multi-Element Radio Linked Interferometer Network (MERLIN), proposed another related explanation. They hypothesized that the light comes from two sources: a supermassive black hole at the center of IC 2497, and light produced by an interaction of an energetic jet from that black hole and the gas surrounding IC 2497.
with the XMM-Newton
and Suzaku
X-ray space telescopes to probe the current activity of the supermassive black hole have been arranged.
Dutch language
Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
for Hanny's object, is an astronomical object of unknown nature. It was discovered in 2007 by Dutch
Dutch people
The Dutch people are an ethnic group native to the Netherlands. They share a common culture and speak the Dutch language. Dutch people and their descendants are found in migrant communities worldwide, notably in Suriname, Chile, Brazil, Canada, Australia, South Africa, New Zealand, and the United...
school teacher Hanny van Arkel, while she was participating as an amateur volunteer in the Galaxy Zoo
Galaxy Zoo
Galaxy Zoo is an online astronomy project which invites members of the public to assist in the morphological classification of large numbers of galaxies. It is an example of citizen science as it enlists the help of members of the public to help in scientific research. An improved version—Galaxy...
project. Photographically, it appears as a bright blob close to spiral galaxy
Spiral galaxy
A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
IC 2497
IC 2497
IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp.IC 2497 is a former quasar, whose light lit up Hanny's Voorwerp, which is now a light echo of that extinct quasar. It is about away from Hanny's Voorwerp. The quasar shut down sometime in the last 70,000 years...
in the constellation Leo Minor
Leo Minor
Leo Minor is a small and faint constellation. Its name means "the smaller lion", in contrast to Leo, the larger lion. Its brightest stars form a rough triangle, and it lies between the larger and more recognizable Ursa Major and Leo...
.
Description
The object, now referred to as a "voorwerp", is about the size of our Milky WayMilky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy and has a huge central hole over 16,000 light years across. In the image, the voorwerp is colored green, a false color that is standardly used to represent the presence of several luminous emission lines of glowing oxygen. It has been shown to be at the same distance from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
as the adjacent galaxy, both about 650 million light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away.
Star birth is occurring in the region of the object that faces IC 2497. Radio observations indicate that this is due to an outflow of gas arising from the IC 2497's core which is interacting with a small region of Hanny's Voorwerp to collapse and form stars. The youngest stars are several million years old.
A picture of the object appeared on the Astronomy Picture of the Day
Astronomy Picture of the Day
Astronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
website in data taken by Dan Smith (Liverpool John Moores University
Liverpool John Moores University
Liverpool John Moores University is a British 'modern' university located in the city of Liverpool, England. The university is named after John Moores and was previously called Liverpool Mechanics' School of Arts and later Liverpool Polytechnic before gaining university status in 1992, thus...
), Peter Herbert (University of Hertfordshire
University of Hertfordshire
The University of Hertfordshire is a new university based largely in Hatfield, in the county of Hertfordshire, England, from which the university takes its name. It has more than 27,500 students, over 2500 staff, with a turnover of over £181m...
) and Chris Lintott (University of Oxford
University of Oxford
The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...
) on the 2.5 metre Isaac Newton Telescope
Isaac Newton Telescope
The Isaac Newton Telescope or INT is a 2.54 m optical telescope run by the ING at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984....
.
Hypotheses
One hypothesis suggests that it consists of remnants of a small galaxy showing the impact of radiation from a bright quasarQuasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
event that occurred in the center of a nearby galaxy, IC 2497
IC 2497
IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp.IC 2497 is a former quasar, whose light lit up Hanny's Voorwerp, which is now a light echo of that extinct quasar. It is about away from Hanny's Voorwerp. The quasar shut down sometime in the last 70,000 years...
about 100,000 years previously. The quasar event is thought to have stimulated the bright emission that characterizes the voorwerp. The quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
may have switched off in the last 200,000 years, and is not visible in the available images.
One possible explanation for the missing light-source is that illumination from the assumed quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
was a transient phenomenon
Transient astronomical event
A transient astronomical event, often simply called in context by astronomers a transient, is an astronomical object or phenomenon which can be observed for a short period of time...
. In this case, its effects on the voorwerp would be still visible because of the distance of several tens of thousands of light years between the voorwerp and the quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
in the nearby galaxy: the voorwerp would show a "light echo
Light echo
thumb|right|250px|Reflected light following path B arrives shortly after the direct flash following path A but before light following path C. B and C have the same apparent distance from the star as seen from [[Earth]]....
" or "ghost image," of events that are older than those currently seen in the galaxy.
On 17 June 2010, a group of researchers at the European Very Long Baseline Interferometry Network (EVN) and the UK’s Multi-Element Radio Linked Interferometer Network (MERLIN), proposed another related explanation. They hypothesized that the light comes from two sources: a supermassive black hole at the center of IC 2497, and light produced by an interaction of an energetic jet from that black hole and the gas surrounding IC 2497.
Further study
The voorwerp and the neighboring galaxy are the object of active astrophysical research. Observations of IC 2497IC 2497
IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp.IC 2497 is a former quasar, whose light lit up Hanny's Voorwerp, which is now a light echo of that extinct quasar. It is about away from Hanny's Voorwerp. The quasar shut down sometime in the last 70,000 years...
with the XMM-Newton
XMM-Newton
The XMM-Newton is an orbiting X-ray observatory launched by ESA in December 1999 on a Ariane 5 rocket...
and Suzaku
ASTRO-E
Suzaku is a Japanese X-ray astronomy satellite launched on 10 July 2005 aboard the M-V-6 rocket. The project was renamed Suzaku after its successful launch after the mythical Vermilion bird of the South....
X-ray space telescopes to probe the current activity of the supermassive black hole have been arranged.
External links
- Galaxy Zoo's blue mystery (part I) by Janet Raloff at Science News June 19, 2008
- Galaxy Zoo's blue mystery (part 2) Janet Raloff June 20, 2008
- Hanny's Voorwerp (SDSS J094103.80+344334.2) Hanny's Voorwerp at Bill Keel's pages University of Alabama. Accessed June 2008
- Hanny's Voorwerp - Still Alive and Kicking by Tammy Plotner, Universe Today, June 9, 2008
- www.hannysvoorwerp.com Personal website of discoverer Hanny van Arkel
- Astronomers Solve The Mystery of Hanny's Voorwerp, Technology ReviewTechnology ReviewTechnology Review is a magazine published by the Massachusetts Institute of Technology. It was founded in 1899 as "The Technology Review", and was re-launched without the "The" in its name on April 23, 1998 under then publisher R. Bruce Journey...