Tagged: Helix Nebula Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 5:26 pm on July 23, 2021 Permalink | Reply
    Tags: "Needle in a haystack-planetary nebulae in distant galaxies", As the distance of a planetary nebula increases the apparent diameter in an image shrinks and the integrated apparent brightness decreases with the square of the distance., , , , Helix Nebula, Leibniz Institute for Astrophysics [Leibniz-Institut für Astrophysik](AIP)(DE), , PNLF: luminosity function of planetary nebulae, The method used-a filter algorithm in image data processing-opens up new possibilities for cosmic distance measurement – and thus also for determining the Hubble constant., With modern large telescopes and long exposure times such objects can nevertheless be imaged and measured using optical filters or imaging spectroscopy.   

    From Leibniz Institute for Astrophysics [Leibniz-Institut für Astrophysik](AIP)(DE): “Needle in a haystack-planetary nebulae in distant galaxies” 

    From Leibniz Institute for Astrophysics [Leibniz-Institut für Astrophysik](AIP)(DE)

    July 22, 2021

    Science contacts:
    Prof. Dr.
    Martin M. Roth
    Phone: +49 331 7499 313

    Dr. Peter Weilbacher
    Phone: +49 331 7499 667

    Media contact:
    Sarah Hönig
    Phone: +49 331 7499 803

    The ring galaxy NGC 474 at a distance of about 110 million light years. The ring structure was formed by merging processes of colliding galaxies.
    Credit:DOE’s Fermi National Accelerator Laboratory (US)/Dark Energy Survey (US) /National Center for Supercomputing Applications at the University of Illinois (US) & Cerro Tololo Inter-American Observatory (CL) (US)/NSF NOIRLab (US)/National Science Foundation (US)/ Association of Universities for Research in Astronomy (US).

    Using data from the MUSE instrument, researchers at the Leibniz Institute for Astrophysics Potsdam (AIP) succeeded in detecting extremely faint planetary nebulae in distant galaxies.

    The method used-a filter algorithm in image data processing-opens up new possibilities for cosmic distance measurement – and thus also for determining the Hubble constant.

    Planetary nebulae are known in the neighbourhood of the Sun as colourful objects that appear at the end of a star’s life as it evolves from the red giant to white dwarf stage: when the star has used up its fuel for nuclear fusion, it blows off its gas envelope into interstellar space, contracts, becomes extremely hot, and excites the expanding gas envelope to glow.

    Unlike the continuous spectrum of the star, the ions of certain elements in this gas envelope, such as hydrogen, oxygen, helium and neon, emit light only at certain wavelengths. Special optical filters tuned to these wavelengths can make the faint nebulae visible. The closest object of this kind in our Milky Way is the Helix Nebula, 650 light years away.

    The planetary nebula NGC 7294 (“Helix Nebula”), an object in the neighbourhood of the Sun.
    Credit: National Aeronautics Space Agency (US), NSF NOIRLab National Optical Astronomy Observatory (US), European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU), the Hubble Helix Nebula Team, M. Meixner (Space Telescope Science Institute (US)), and T.A. Rector (National Radio Astronomy Observatory (US))

    As the distance of a planetary nebula increases the apparent diameter in an image shrinks and the integrated apparent brightness decreases with the square of the distance. In our neighbouring galaxy, the Andromeda Galaxy, at a distance almost 4000 times greater, the Helix Nebula would only be visible as a dot, and its apparent brightness would be almost 15 million times fainter. With modern large telescopes and long exposure times such objects can nevertheless be imaged and measured using optical filters or imaging spectroscopy. Martin Roth, first author of the new study and head of the innoFSPEC department at AIP: “Using the PMAS instrument developed at AIP, we succeeded in doing this for the first time with integral field spectroscopy for a handful of planetary nebulae in the Andromeda Galaxy in 2001 to 2002 on the 3.5m telescope of the Calar Alto Observatory.

    However, the relatively small PMAS field-of-view did not allow yet to investigate a larger sample of objects.”

    It took a good 20 years to develop these first experiments further using a more powerful instrument with a more than 50 times larger field-of-view on a much larger telescope. MUSE [above] at the ESO Very Large Telescope in Chile [above] was developed primarily for the discovery of extremely faint objects at the edge of the universe currently observable to us – and has produced spectacular results for this purpose since the first observations. It is precisely this property that also comes into play in the detection of extremely faint PN in a distant galaxy.

    The galaxy NGC 474 is a particularly fine example of a galaxy that, through collision with other, smaller galaxies, has formed a conspicuous ring structure from the stars scattered by gravitational effects. It lies roughly 110 million light years away, which is about 170,000 times further than the Helix Nebula. The apparent brightness of a planetary nebula in this galaxy is therefore almost 30 billion times lower than that of the Helix Nebula and is in the range of cosmologically interesting galaxies for which the team designed the MUSE instrument.

    A team of researchers at the AIP, together with colleagues from the USA, has developed a method for using MUSE to isolate and precisely measure the extremely faint signals of planetary nebulae in distant galaxies with high sensitivity. A particularly effective filter algorithm in image data processing plays an important role here. For the ring galaxy NGC 474, ESO archive data were available, based on two very deep MUSE exposures with 5 hours of observation time each. The result of the data processing: after applying the filter algorithm, a total of 15 extremely faint planetary nebulae became visible.

    MUSE image data in the two marked fields in the above image of the ring structure of NGC 474. Left: Image in the continuum with the band of unresolved stars as well as globular clusters marked by circles. Right: filtered image in the redshifted oxygen emission line, from which the planetary nebulae emerge as point sources from the noise. The artefacts created by instrumental effects have completely disappeared.
    Credit: AIP/M. Roth.

    This highly sensitive procedure opens up a new method for distance measurement that is suitable for contributing to the solution of the currently discussed discrepancy in the determination of the Hubble constant. Planetary nebulae have the property that, physically, a certain maximum luminosity cannot be exceeded. The distribution function of the luminosities of a sample in a galaxy, i.e. the luminosity function of planetary nebulae (PNLF), breaks off at the bright end. This property is that of a standard candle, which can be used to calculate a distance by statistical methods.

    The PNLF method has been developed already in 1989 by team members George Jacoby (NSF’s NOIRLab) and Robin Ciardullo (Penn State University (US)). It has been successfully applied to more than 50 galaxies over the past 30 years, but was limited by the filter measurements used so far. Galaxies with distances greater than that of the Virgo or Fornax clusters were beyond the range. The study, now published in The Astrophysical Journal, shows that MUSE can achieve more than twice the range, allowing an independent measurement of the Hubble constant.

    See the full article here.


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Leibniz Institute for Astrophysics Potsdam (AIP)(DE) is a German research institute. It is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory Potsdam (AOP) founded in 1874. The latter was the world’s first observatory to emphasize explicitly the research area of astrophysics. The AIP was founded in 1992, in a re-structuring following the German reunification.

    The AIP is privately funded and member of the Leibniz Association. It is located in Babelsberg in the state of Brandenburg, just west of Berlin, though the Einstein Tower solar observatory and the great refractor telescope on Telegrafenberg in Potsdam belong to the AIP.

    The key topics of the AIP are cosmic magnetic fields (magnetohydrodynamics) on various scales and extragalactic astrophysics. Astronomical and astrophysical fields studied at the AIP range from solar and stellar physics to stellar and galactic evolution to cosmology.

    The institute also develops research technology in the fields of spectroscopy and robotic telescopes. It is a partner of the Large Binocular Telescope in Arizona, has erected robotic telescopes in Tenerife and the Antarctic, develops astronomical instrumentation for large telescopes such as the VLT of the ESO. Furthermore, work on several e-Science projects are carried out at the AIP.

    Main research areas

    Magnetohydrodynamics (MHD): Magnetic fields and turbulence in stars, accretion disks and galaxies; computer simulations ao dynamos, magnetic instabilities and magnetic convection
    Solar physics: Observation of sunspots and of solar magnetic field with spectro-polarimetry; Helioseismology and hydrodynamic numerical models; Study of coronal plasma processes by means of radio astronomy; Operation of the Observatory for Solar Radio Astronomy[7] (OSRA) in Tremsdorf, with four radio antennas in different frequency bands from 40 MHz to 800 MHz
    Stellar physics: Numerical simulations of convection in stellar atmospheres, determination of stellar surface parameters and chemical abundances, winds and dust shells of red giants; Doppler tomography of stellar surface structures, development of robotic telescopes, as well as simulation of magnetic flux tubes
    Star formation and the interstellar medium: Brown dwarfs and low-mass stars, circumstellar disks, Origin of double and multiple-star systems
    Galaxies and quasars: Mother galaxies and surroundings of quasars, development of quasars and active galactic cores, structure and the story of the origin of the Milky Way, numerical computer simulations of the origin and development of galaxies
    Cosmology: Numerical simulation of the formation of large-scale structures. Semi-analytic models of galaxy formation and evolution. Predictions for future large observational surveys.

  • richardmitnick 1:20 pm on July 19, 2017 Permalink | Reply
    Tags: , , , , , Distant radio quasars, Helix Nebula, Nearby Hot Stars May Change Our View of Distant Sources, Variable twinkling   

    From AAS NOVA: “Nearby Hot Stars May Change Our View of Distant Sources” 


    American Astronomical Society

    19 July 2017
    Susanna Kohler

    Clumps of hydrogen gas in the Helix Nebula have been drawn out into long, ionized streamers, as visible in this Hubble image. Could gas like this be responsible for the twinkling of distant quasars? [C. R. O’Dell/K. Handron/NASA/Manly Astrophysics]

    As if it weren’t enough that quasars — distant and bright nuclei of galaxies — twinkle of their own accord due to internal processes, nature also provides another complication: these distant radio sources can also appear to twinkle because of intervening material between them and us. A new study has identified a possible source for the material getting in the way.

    A Spitzer infrared view of the Helix nebula, which contains ionized streamers of gas extending radially outward from the central star. [NASA/JPL-Caltech/Univ. of Ariz.]

    NASA/Spitzer Telescope

    Unexplained Variability

    Distant quasars occasionally display extreme scintillation, twinkling with variability timescales shorter than a day. This intra-day variability is much greater than we can account for with standard models of the interstellar medium lying between the quasar and us. So what could cause this extreme scattering instead?

    The first clue to this mystery came from the discovery of strong variability in the radio source PKS 1322–110. In setting up follow-up observations of this object, Mark Walker (Manly Astrophysics, Australia) and collaborators noticed that, in the plane of the sky, PKS 1322–110 lies very near the bright star Spica. Could this be coincidence, or might this bright foreground star have something to do with the extreme scattering observed?

    Diagram explaining the source of the intra-day radio source variability as intervening filaments surrounding a hot star. [M. Walker/CSIRO/Manly Astrophysics]

    Swarms of Clumps

    Walker and collaborators put forward a hypothesis: perhaps the ultraviolet photons of nearby hot stars ionize plasma around them, which in turn causes the extreme scattering of the distant background sources.

    As a model, the authors consider the Helix Nebula, in which a hot, evolved star is surrounded by cool globules of molecular hydrogen gas. The radiation from the star hits these molecular clumps, dragging them into long radial streamers and ionizing their outer skins.

    Though the molecular clumps in the Helix Nebula were thought to have formed only as the star evolved late into its lifetime, Walker and collaborators are now suggesting that all stars — regardless of spectral type or evolutionary stage — may be surrounded by swarms of tiny molecular clumps. Around stars that are hot enough, these clumps become the ionized plasma streamers that can cause interference with the light traveling to us from distant sources.

    Significant Mass

    To test this theory, Walker and collaborators explore observations of two distant radio quasars that have both exhibited intra-day variability over many years of observations. The team identified a hot A-type star near each of these two sources: J1819+3845 has Vega nearby, and PKS 1257–326 has Alhakim.

    Locations of stars along the line of site to two distant quasars, J1819+3845 (top panel) and PKS 1257–326 (bottom panel). Both have a nearby, hot star (blue markers) radially within 2 pc: Vega (z = 7.7 pc) and Alhakim (z = 18 pc), respectively. [Walker et al. 2017]

    By modeling the systems of the sources and stars, the authors show that the size, location, orientation, and numbers of plasma concentrations necessary to explain observations are all consistent with an environment similar to that of the Helix Nebula. Walker and collaborators find that the total mass in the molecular clumps surrounding the two stars would need to be comparable to the mass of the stars themselves.

    If this picture is correct, and if all stars are indeed surrounded by molecular clumps like these, then a substantial fraction of the mass of our galaxy could be contained in these clumps. Besides explaining distant quasar scintillation, this idea would therefore have a significant impact on our overall understanding of how mass in galaxies is distributed. More observations of twinkling quasars are the next step toward confirming this picture.


    Mark A. Walker et al 2017 ApJ 843 15. doi:10.3847/1538-4357/aa705c

    Related Journal Articles
    Further references complete with links on the full article.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

  • richardmitnick 9:17 am on October 6, 2016 Permalink | Reply
    Tags: Helix Nebula, ,   

    From Rafa Leon at IAC: The Helix Nebula 


    Instituto de Astrofísica de Canarias – IAC


    The Helix Nebula, are already 10 shots that are few but it’s what’s up, this is the first that sack of this object,
    The Helix Nebula, HELIX NEBULA OR NGC 7293, is a planetary nebula in the constellation of Aquarius, approximately 680 light years away. It is one of the planetary nebulae closest to the earth and was discovered by Karl Ludwig Harding before 1824., they look very similar to the ring nebula (M57) and its physical characteristics are similar to those of the Dumbbell Nebula (M27 ).

    This nebula is an example of a planetary nebula formed by a sun-like star in the last stages of his life. The gases expelled by the star appear from our perspective as if we saw a propeller from the top, where it comes from his name. The Remnant Star is a white dwarf. The age of the nebula, based on his pace of expansion, is estimated at about 10,600 years or so.

    A team of astronomers has established that the structure of this nebula is more complex than what was initially believed, consisting of two discs gaseous placed almost perpendicular in relation to each other. X-ray observations provide evidence on the existence of a companion star. So, one of the disks may be perpendicular to the axis of rotation of the dying star, while the other is located in the orbital plane of the two stars. It was also believed that the records were formed during two different periods in where there was loss of mass on the part of the dying star. So, while the inner disc was formed about 6600 years ago, the outside came 12 000 years ago. In addition, the inner disc is expanding something faster than the outside.

    Despite his apparent large size, it is a difficult object to see due to its spread, requiring dark skies and the use of instruments as light as possible, like binoculars or a telescope operating at Low Magnification. A Nebular Filter attached to the eye of the telescope can help enough to your comment.

    Rafael Leon Batista © 2016 Gran Canaria

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teachingand outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

    Gran Telescopio  Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC
    Gran Telescopio CANARIAS, GTC

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc
%d bloggers like this: