, (

Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...

for ''Hanny's object'') is a rare type of astronomical object called a

quasar A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a m ...

ionization echo. It was discovered in 2007 by

schoolteacher Hanny van Arkel while she was participating as a volunteer in the

Galaxy Zoo Galaxy Zoo is a crowdsourced astronomy project which invites people 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 scien ...

project, part of the

Zooniverse Zooniverse is a citizen science web portal owned and operated by the Citizen Science Alliance. It is home to some of the Internet's largest, most popular and most successful citizen science projects. The organization grew from the original Gal ...

group of

citizen science Citizen science (CS) (similar to community science, crowd science, crowd-sourced science, civic science, participatory monitoring, or volunteer monitoring) is scientific research conducted with participation from the public (who are sometimes re ...

websites. Photographically, it appears as a bright blob close to

spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''IC 2497 IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp. The galaxy 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 ...

in the constellation

Leo Minor Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Le ...

Description

Hanny's Voorwerp (HsV) is about the size of a small galaxy and has a central hole over 16,000

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s across. In an image taken with the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

, HsV is colored green, a standard

false color False color (or pseudo color) refers to a group of color rendering methods used to display images in color which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an image that depicts ...

that is used to represent the presence of several luminous

emission line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s of glowing

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

. HsV has been shown to be at the same distance from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

as the adjacent galaxy IC 2497, which is about 650 million light-years away. Star birth is occurring in the region of HsV that faces IC 2497. Radio observations indicate that this is due to an outflow of gas from IC 2497's core which is interacting with a small region of HsV to collapse and form stars. The youngest of these stars are several million years old. A 40-page comic and associated promotional offers about HsV and the story surrounding it were presented at the 24th

Dragon Con Dragon Con (previously Dragon*Con and sometimes DragonCon) is a North American multigenre convention, founded in 1987, which takes place annually over the Labor Day weekend in Atlanta, Georgia. , the convention draws attendance of over 80,000, f ...

Atlanta Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,715 ...

on 3 September 2010, as well as first pictures of HsV from the

. The launch was streamed live on UStream.

Hypotheses

One

hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

suggests that HsV consists of remnants of a small galaxy showing the impact of radiation from a bright

event that occurred in the center of IC 2497 about 100,000 years before how it is observed today. The quasar event is thought to have stimulated the bright emission that characterizes HsV. The quasar might have switched off in the last 200,000 years and is not visible in the available images. This might well be due to a process known as AGN feedback. 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 HsV would be still visible because of the distance of several tens of thousands of

s between HsV and the

in the nearby galaxy: HsV would show a "

light echo 309x309px, 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.">Earth.html" ;"title="apparent distan ...

" 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 VLBI Network The European VLBI Network (EVN) is a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa and Puerto Rico, which performs very high angular resolution observations of cosmic radio sources usin ...

(EVN) and the UK's

Multi-Element Radio Linked Interferometer Network Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and leg ...

(MERLIN), proposed another related explanation. They hypothesized that the light comes from two sources: (1) a

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical obj ...

at the center of IC 2497, and (2) light produced by an interaction of an energetic jet from the black hole and the gas surrounding IC 2497.

Voorwerpjes

In February 2012, W. C. Keel and others published a paper in the ''

Monthly Notices of the Royal Astronomical Society ''Monthly Notices of the Royal Astronomical Society'' (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes letters and papers reporting orig ...

''. As a result of the interest in similar ionized clouds for the study of both the history and obscuration of

Active Galactic Nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...

(AGN), participants in the

(GZ) project carried out a wide search for such clouds using data from the

Sloan Digital Sky Survey The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project began in 2000 a ...

(SDSS). This search yielded a list of 19 galaxies with AGN-photoionized clouds detected to beyond 10

kiloparsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s from the nuclei. These were nicknamed 'Voorwerpjes' from the

for 'small objects'. In August 2013, F. Schweizer and others published a paper in the ''

Astrophysical Journal ''The Astrophysical Journal'', often abbreviated ''ApJ'' (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and Jame ...

''. This reports the finding of a Voorwerpje on the outskirts of the well-studied NGC 7252. In May 2015, W.C. Keel and others published a study in the ''

''. This studies 8 of the original 19 Voorwerpjes in greater detail, focusing on "the host-galaxy properties and origin of the gas". Among the telescopes used was the 6 meter

BTA-6 The BTA-6 (russian: Большой Телескоп Альт-азимутальный, translit=Bolshoi Teleskop Alt-azimutalnyi, translation=Large Altazimuth Telescope) is a aperture optical telescope at the Special Astrophysical Observatory lo ...

at the

Special Astrophysical Observatory of the Russian Academy of Science The Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS; russian: Специальная Астрофизическая Обсерватория) is an astronomical observatory, set up in 1966 in the USSR, and now operat ...

. In February 2018, Treister et al. studied the galaxy Mrk 463 with VLT/MUSE, VLT/Sinfoni and

ALMA Alma or ALMA may refer to: Arts and entertainment * ''Alma'' (film), a 2009 Spanish short animated film * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''Alma'' (play), a 1996 drama by Joshua Sobol about Alma ...

. This study found extended emissions around this galaxy and that the

accretion rate on the Mrk 463E nucleus changed by a factor 3–20 in the last 40,000 years, similar to other Voorwerpje galaxies. Galaxy zoo volunteers did identify this galaxy as a candidate Voorwerpje, but the IIIemission was already described by earlier studies. In March 2018, Lansbury et al. studied the Teacup Galaxy, also known as the Teacup AGN or SDSS J1430+1339 in x-rays with

Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

and

Chandra Chandra ( sa, चन्द्र, Candra, shining' or 'moon), also known as Soma ( sa, सोम), is the Hindu god of the Moon, and is associated with the night, plants and vegetation. He is one of the Navagraha (nine planets of Hinduism) and ...

. The extended clouds around the Teacup AGN consist of an "eastern bubble", seen in optical images, and a "western bubble", only seen in radio images by the

Very Large Array The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~ west of Socorro. The VLA comprises twen ...

. The Chandra observations revealed a loop in x-ray emission, consistent with the "eastern bubble". The Chandra data also show evidence for hotter gas within the bubble, which may imply that a wind of material is blowing away from the black hole. Such a wind, which was driven by radiation from the quasar, may have created the bubbles found in the Teacup. The observations in x-rays revealed a powerful, highly obscured

active galactic nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...

. This new result suggests that the AGN might not require fading. The quasar has dimmed by only a factor of 25 or less over the past 100,000 years. In March 2019, Keel et al. studied AGN photoionization of gas in galaxy pairs. The study found UGC 6081 as a candidate Voorwerpje, using data from the 2.5-meter telescope of the

Caucasus Mountain Observatory The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historically ...

. The emission extends 18 kpc from both AGN.

Gallery

The Teacup Galaxy SDSS 1430.jpg, A

image of the Teacup Galaxy SDSS 1430 +13, a Voorwerpje. CREDITS:

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

ESA , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

and William Keel VLA-Finds-Unexpected-Storm-at-Galaxys-Core.jpg, Teacup Galaxy SDSS 1430 +13 with images from Hubble (blue) and the

(orange), showing both bubbles NGC 5972.jpg, The Voorwerpje around NGC 5972 Hs-2015-13-d-large web.jpg, The Voorwerpje around SDSS 1510+07 Heic1507e.jpg, The Voorwerpje around UGC 7342 Heic1507f.jpg, The Voorwerpje around NGC 5252 Hs-2015-13-g-large web.jpg, The Voorwerpje around Markarian 1498 Heic1507h.jpg, The Voorwerpje around UGC 11185 Hs-2015-13-i-large web.jpg, The Voorwerpje around SDSS 2201+11 NGC 7252.jpg, Picture of NGC 7252. This picture was taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at

ESO The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based ast ...

La Silla Observatory La Silla Observatory is an astronomy, astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are located at the site and are partly maintained by ESO. The obse ...

Extended X-ray emission in IC 2497

In April 2016, a study was published in the ''

'' using data gathered by the

Chandra X-ray Observatory The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...

in January 2012. The study found extended soft X-ray emission in

IC 2497 IC 2497 is a spiral galaxy close to the intergalactic cloud Hanny's Voorwerp. The galaxy 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 ...

which suggested the presence of a bubble or cavity surrounding the AGN. The authors hypothesize that this could be due to the bubble being inflated by the AGN, or by a past luminous quasar.

References

External links

The history of the discovery on Hanny van Arkel's personal websiteHubble Space Telescope Delivers Images of Ethereal Green 'Phantoms'
"Voorwerps" discussion at Motherboard, April 5, 2015 20070718 Dwarf galaxies Leo Minor Citizen science