(

Dutch Dutch or Nederlands commonly refers to: * Something of, from, or related to the Netherlands ** Dutch people as an ethnic group () ** Dutch nationality law, history and regulations of Dutch citizenship () ** Dutch language () * In specific terms, i ...

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

quasar A quasar ( ) is an extremely Luminosity, luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass rangi ...

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 galaxy morphological classification, morphological classification of large numbers of galaxy, galaxies. It is an example of citizen science as it enlists the he ...

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, citizen science projects. The organization grew from ...

group of

citizen science The term citizen science (synonymous to terms like community science, crowd science, crowd-sourced science, civic science, participatory monitoring, or volunteer monitoring) is research conducted with participation from the general public, or am ...

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

spiral galaxy Spiral galaxies form a galaxy morphological classification, class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''

IC 2497 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 Leo ...

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 (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s across. In an image taken with the

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

, HsV is colored green, a standard

false color False colors and pseudo colors respectively refers to a group of color rendering methods used to display images in colors which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an im ...

that is used to represent the presence of several luminous

emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

s of glowing

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. 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 Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

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. ...

Atlanta Atlanta ( ) is the List of capitals in the United States, capital and List of municipalities in Georgia (U.S. state), most populous city in the U.S. state of Georgia (U.S. state), Georgia. It is the county seat, seat of Fulton County, Georg ...

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 (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess o ...

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 image:Light Echo Corrected.png, 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. A ligh ...

" 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 The Multi-Element Radio Linked Interferometer Network (MERLIN) is an interferometer array of radio telescopes spread across England. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of UK Resea ...

(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 ...

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 in astronomy, astrophysics and related fields. It publishes original research in two formats: papers (of any length) and letters (limited to ...

''. 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 emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...

(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, a ...

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'' (''ApJ'') is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler. The journal discontinued its print edition and ...

''. 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 () is a aperture optical telescope at the Special Astrophysical Observatory of the Russian Academy of Science, Special Astrophysical Observatory located in the Zelenchuksky District of Karachay-Cherkessia on the north side of the Cauca ...

at the

Special Astrophysical Observatory of the Russian Academy of Science The Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS; ) is an astronomical observatory, set up in 1966 in the USSR, and now operated by the Russian Academy of Sciences. Based in the Bolshoi Zelenchuk Valley of the Grea ...

. 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'', an upcoming film by Sally Potter * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''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 The Teacup galaxy, also known as the Teacup AGN or SDSS J1430+1339 is a low redshift type 2 quasar, showing an extended loop of ionized gas resembling a handle of a teacup, which was discovered by volunteers of the Galaxy Zoo project and labeled ...

, 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 * SWIF ...

and

Chandra Chandra (), also known as Soma (), 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 Dikpala (guardians of the directions). Etymology and other ...

. 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 in the southwestern United States built in the 1970s. It lies in central New Mexico on the Plains of San Agustin, between the towns of Magdalena, Ne ...

. 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 emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such e ...

. 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 UGC may refer to: Organisations * Canadian Geophysical Union, official abbreviation in French (Union géophysique canadienne) * UGC (cinema operator), a European cinema chain, formerly Union Générale Cinématographique * UGC Fox Distribution, a ...

as a candidate Voorwerpje, using data from the 2.5-meter telescope of the Caucasus Mountain Observatory. The emission extends 18 kpc from both AGN.

Gallery

The Teacup Galaxy SDSS 1430.jpg, A

image of the

SDSS 1430 +13, a Voorwerpje. CREDITS:

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

ESA The European Space Agency (ESA) is a 23-member international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European ...

and William Keel VLA-Finds-Unexpected-Storm-at-Galaxys-Core.jpg,

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 SDSS may refer to: * Sloan Digital Sky Survey, a major multi-filter imaging and spectroscopic redshift survey * Social Democratic Party of Slovakia * Spatial Decision Support System, a GIS based decision aiding system * Independent Democratic Serb ...

Heic1507e.jpg, The Voorwerpje around UGC 7342 Heic1507f.jpg, The Voorwerpje around

NGC 5252 NGC 5252 is a lenticular galaxy located in the constellation Virgo (constellation), Virgo. It is located at a distance of about 220 to 320 million light years from Earth, which, given its apparent dimensions, means that NGC 5252 is about 100,000 l ...

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 SDSS may refer to: * Sloan Digital Sky Survey, a major multi-filter imaging and spectroscopic redshift survey * Social Democratic Party of Slovakia * Spatial Decision Support System, a GIS based decision aiding system * Independent Democratic Serb ...

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 Southern Observatory is an astronomical research organisation. ESO may also refer to: *Employee stock option (also: executive stock option) *'' Ether Saga Odyssey'', a fantasy massively multiplayer online role-playing game *''The Elde ...

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

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 ...

in January 2012. The study found extended soft X-ray emission in IC 2497 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 Discoveries by amateur astronomers