Astronomy Object of the Month: Archive
| August: Non-interacting coronal mass ejections and solar energetic particles near the quadrature configuration of Solar TErrestrial RElations Observatory |
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Space weather is mainly controlled by the
strong magnetic storms and particle storms which are caused by the enhanced
fluxes of protons and ions. These accelerated plasmas are known as solar energetic particles (SEPs). The generation of SEP is mainly due to two
phenomenon, impulsive SEP events caused by magnetic reconnection manifested as solar flares, and gradual SEP events accelerated by strong shocks
associated with coronal mass ejections (CMEs). In this paper we
have shown that our method of employing so-called instantaneous speed (maximum speed and the CME speed and Mach number at SEP peak flux) offers
better correlation than the average speed. In addition, we observe poor correlation between fluxes of SEPs and Flares, which
support the hypothesis that energetic particles observed in the considered energy range are predominantly accelerated by CME shock. More... |
| July: The discovery of high-energy gamma rays from the jet of the active galaxy Centaurus A |
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On June 17, journal Nature published the paper of researchers from the international
H.E.S.S. Observatory,
presenting the discovery of high-energy gamma emission from the relativistic beam, or "jet", of the
nearby active galaxy Centaurus A (Cen A). This important astronomical discovery was made with
participation of Polish scientists, including the team from the Astronomical Observatory of the
Jagiellonian University. More... |
| June: Pulsating blue subdwarfs and planets which are not there |
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In 2011 and 2014, reports appeared that two pulsating sdBV stars observed by the Kepler Space Telescope,
KIC 5807616 and KIC 10001893, could be circled by extrasolar planets on tight orbits. However, a new
analysis of the putative planetary signatures found in the light curves of these stars shows that there
are no planets around them. The research involved professor Jerzy Krzesiński from the Astronomical
Observatory of the Jagiellonian University in Kraków and his PhD student Adam Blokesz from the Pedagogical
University of Kraków. More... |
| May: Spitzer Telescope test Einstein Gravity: repeated explosions near a black hole give a clue |
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A very recent observation of a predicted flaring from a distant galaxy by Spitzer Space Telescope has firmly established the
existence of a massive black hole pair emitting nano-Hertz gravitational waves which should assist the on-going international
efforts to directly detect such waves. Spitzer observation is also constraining a unique property of black holes, explored by
Stephen Hawking and collaborators. More... |
| April: Examination of microvariability of the flux and the polarization of blazars in the optical band |
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Active Galactic Nuclei (AGNs) consists of galaxies with extremely bright nucleus, so much so, that they usually
outshine the light from other galaxy parts such as arms or bulges. The reason behind intense power of AGN is believed
to be that at the centre of galaxy a super massive black hole (SMBH) is accreting matter from its vicinity. Sometimes,
such systems are known to erupt powerful, narrow beam of high velocity charged particles. If one happens to view such
a systems along the line of sight of these eruptions (jets) are called blazars. The emission from blazar jets is Doppler
boosted, leading to extreme luminosities and flux variability and apparent superluminal motion shown by the ejecta. More... |
| March: The Nature of γ-ray Variability in Blazars |
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Blazars shine predominatly in high energy emission, e. g. X-ray and gamma-ray wave bands. It is widely believed
that the high energy emission is produced via synchrotron and inverse-Compton processes at the relativistic shock
waves which propagate along the blazar jets or magnetic reconnection processes in case of highly magnetized jets.
However, in spite of the collaborative efforts of several modern space and earth bound telescopes, the details of
the mechanisms and the exact location of the production of the high energy emission, in reference to the
central engine, remain elusive. More... |
| February: CSO radio sources and efficiency of their jets |
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The international team headed by astronomers from the Jagiellonian University has published detailed
research on the jet production efficiency in a sample of 17 selected young radio galaxies, for which the
observed luminosities of their jets, radio lobes and accretion disks seem to correspond to the same
episode of the central activity of their parent galaxies. More... |
| January: The catalogue of giant radio sources |
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Giant radio sources are a peculiar class of objects due to the extremely large (> 0.7 Mpc) sizes of their observed radio
structures. It is believed that this is relatively rare feature, because only ~5% of all known radio sources exceed this
size. The reasons why some radio sources have grown to such large sizes are not fully explained, however detailed multiwavelength
studies have progressed significantly our knowledge about the nature of giants. More... |
| December: First detection of gamma-ray burst afterglow in very-high-energy gamma light |
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After a decade-long search, scientists have for the first time detected a gamma-ray burst in very-
high-energy gamma light. This discovery was made in July 2018 by the H.E.S.S. collaboration
using the huge 28-m telescope of the
H.E.S.S. array in Namibia. Surprisingly, this Gamma-ray
burst, an extremely energetic flash following a cosmological cataclysm, was found to emit very-
high-energy gamma-rays long after the initial explosion. More... |
| November: Interstellar Comet with a Familiar Look |
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A new comet discovered by amateur astronomer Gennady Borisov is an outcast from another star system, yet its
properties determined so far are surprisingly familiar – a new study led by JU researchers shows. The team’s
findings are being published in Nature Astronomy on 14 October 2019. More... |
| October: Estimation of Arrival Time of Coronal Mass Ejections in the vicinity of the Earth |
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The arrival time of coronal mass ejections (CMEs) in the vicinity of the Earth is one of the most important parameters in determining space weather. An accurate model for prediction of travel time (TT) of CMEs directed towards Earth is important as they cause intense geomagnetic disturbances. Our study provides prediction model with lesser errors compared to previous methods. In addition this gives us a better understanding of the kinematics of CMEs. More... |
| September: Needle-like structures on positively charged lightnings |
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Thunderbolts occuring in Earth’s atmosphere are dangerous yet still poorly understood natural phenomenon. Typical lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends—so-called positive and negative lightning leaders. More... |
| August: Rhythmic oscillations of the blazar Markarian 501 |
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Dr. Gopal Bhatta from the Jagiellonian University in Kraków has detected transient rhythmic oscillations
in the gamma-ray emission from the
blazar Markarian 501. The discovery could be helpful in improving our understanding of the most energetic processes
taking place in the universe. More... |
| July: Signatures of UV radiation around low-mass protostars in Serpens |
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A new-born protostar forms in dense core deep inside molecular cloud.
Molecular cloud is characterised by high extinction in the optical
range so observations at long wavelengths are necessary. In particular, submillimetre spectra include
rotational lines of key molecules which are useful tracers
of physics and chemistry around low-mass protostars. The column densities of HCN and CN molecules can be determined with the RADEX radiative
transfer code. This information can be compared with an astrochemical model in order to characterise the strength of the UV radiation. Thus,
we gain new understandings of chemical and physical processes around low-mass protostars. More... |
| June: Dusty galaxies from the AKARI All Sky Survey |
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Recent studies show that optically selected AGNs often follow the far infrared-to-radio correlation as tightly as star forming
galaxies. Most galaxies containing AGNs have their far infrared-to-radio flux ratios indistinguishable from those of the star
forming ones, with the exception of Seyfert galaxies. To study this dependence more accurately, international team led by
astronomers from National Centre for Nuclear Research and Jagiellonian University used the newest measurements from the AKARI
Far-Infrared All Sky Survey to cross-correlate the AKARI data with the NVSS radio catalogue at 1.4 GHz. More... |
| May: New method of constructing inhomogeneous cosmological models |
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Studies of inhomogeneous cosmological models are an actively developed branch of
general relativity and cosmology. By developing new techniques for solving the physically motivated issues of Einstein's theory of gravity, we
expand our knowledge of the Universe with unknown phenomena and set future directions for research. More... |
| April: Gamma-Ray Bursts zoo sorted in 3D |
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A powerful tool for characterizing and classifying gamma-ray
bursts (GRBs) to allow their use as tracers of the expansion history of the universe has recently been presented by an
international team of researchers led by Dr. Maria Dainotti, assistant Professor at Jagiellonian University, Poland and concurrently
serve as Chretienne Fellow appointed by the American Astronomical Society at Stanford University. The work, which has been published
in the Astrophysical Journal, is a statistical analysis of the properties of the yet mysterious GRBs, aimed at determining a sub-group
of GRBs and investigating the physical origin of these systems. More... |
| March: Compact galaxy groups observed with LOFAR radio interferometer | ||
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LOFAR Two-metre Sky Survey (LoTSS) has detected
thousands of new galaxies. International team — including scientists from the Astronomical Observatory of the
Jagiellonian University — used this survey to identify the groups of galaxies from the
Hickson Compact Groups and Magnitude
Limited Compact Groups samples that emit at the low radio frequency of 150 MHz. Their radio emission was then
characterised and the newly obtained results were compared to earlier observations and theoretical predictions for the groups. More... |
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| February: Stars, galaxies and quasars from the Infrared WISE Survey | ||
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The Wide-field Infrared Survey Explorer (
WISE) satellite has detected hundreds of millions of new infrared sources. Classifying them reliably is, however,
a very challenging task. Simple colour cuts are often not sufficient; for satisfactory levels of completeness and purity,
more sophisticated classification methods are needed. A team of astronomers from Jagiellonian University and other Polish
research centers is developing new, automated methods of source classification in full-sky WISE data. More... |
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| January: Possible link between relativistic jets and accretion disk found in the giant quasar 4C+74.26 | ||
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4C+74.26 is a quasar located about 1.4 billion light years away from us - one of the few quasars with giant radio lobes
spreading across millions light years. An team of researchers led by Dr. Gopal Bhatta from the Jagiellonian University in
Kraków studied the source using multifrequency observations from the ground and space based telescopes. The team discovered
that the optical emission delayed behind radio emission by ~250 days. The authors proposed that the delay may indicate a
scenario in which flux modulations arose due to magnetic disruptions at the innermost regions of the accretion disk. Such
a lag between two emission bands is relatively rarely observed and it could help in understating the most challenging
issues in modern astrophysics. More... |
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| December: Kordylewski Clouds – dust moons of the Earth-Moon System | ||
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At the end of October 2018, an interesting set of publications, by a team of Hungarian scientists, were published
in the Monthly Notices of the Royal Astronomical Society. Judith Sliz-Balogh, Andras Bart and Gabor Horvath reported their observations
of the Earth’s dust moon. The initiator of the search for these dusty moons of Earth was doc. Kazimierz Kordylewski from the Astronomical
Observatory of the Jagiellonian University. More... |
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| November: Blazars observed behind the Magellanic Clouds | ||
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Identification of AGNs in dense stellar fields such as the Large and
Small Magellanic Clouds (MCs) is extremely challenging due to large densities of stars in the interstellar medium. Among the 758 MQS quasars
and 898 unidentified objects, a sample of 44 blazar candidates were identified with respect to their radio, optical, and
mid-infrared properties. The newly selected blazar candidates possess the long-term multi-colour (I nad V filters) photometric
data from the OGLE, multi-colour mid-infrared observations, and archival radio data for at least one frequency. Moreover, nine blazar
candidates have radio polarization data. The results are accepted by Astrophysical Journal. More... |
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| October: SBS B1646+499: black hole with a jumbled past | ||
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Blazars constitute a particular class of so-called active galaxies (AGNs). These exotic objects emit huge amount of energy.
Blazars host very masive black holes in their centers, surrounded by accretion discs and toruses. Their high-energy radiation is mostly emitted in
collimated streams called jets. The emission of such objects is dominated by the relativistically boosted, non-thermal emission of the jets observed at
a small angle to the observer on Earth. In the case of blazar SBS B1646+499, the galaxy activity phase associated with the jet production has already
occurred at least twice. The results are accepted by Astrophysical Journal. More... |
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| September: Detection of Periodic Radio Signal from the Blazar PKS 0219-164 | ||
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PKS 0219-164 (z=0.7) is a BL Lac source that been detected over a broad range of the electromagnetic spectrum including radio, infra-red, optical,
X and gamma rays. The accurate position of the source at radio frequency (2700 MHz) and its optical counterpart was measured in 1977.
The decade-long 15 GHz radio observations of the blazar PKS 0219-164 from the 40-m telescope OVRO
were recently analyzed. Study revealed a strong repeating signal with a periodicity of ∼270 days. The results are published in
Astrophysical Journal More... |
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| August: TXS 0506+56: discovery of an energetic cosmic neutrino source due to very high energy gamma ray observations | ||
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On September 22nd last year the Ice Cube Neutrino Observatory at the South
Pole detected a high energy neutrino with a likely cosmic origin. A single neutrino does not suffice to identify its source. Very soon after
its detection telescopes working at different wavelengths of the electromagnetic spectrum started to observe the possible location it came from.
The results are published in Science. More... |
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| July: First long term all-frequency power spectral analysis of OJ 287 | ||
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The international team headed by Dr Arti Goyal from the Astronomical Observatory of the Jagiellonian University conducted
the first long term all-frequency power spectral analysis for OJ 287, using also the data from Kepler satellite and constructing the
optical variability power spectrum without any gaps. The results are published in The Astronomical Journal. More... |
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| June: In-depth measurements of the interstellar asteroid ‘Oumuamua unveil its turbulent past and verify previous reports | ||
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‘Oumuamua is the first astronomical object known to science to have entered the Solar System from the interstellar space, having been ejected from its
original planetary system. Using the giant Gemini North telescope in Hawaii, a team of scientists led
by astronomers from the Jagiellonian University in Kraków conducted an in-depth study of the body. Among other findings, the study revealed that ‘Oumuamua is
“tumbling” through space, consistent with a collision in the distant past, as well as verified and expanded upon a number of previous reports. The results
have just appeared in the latest issue of Nature Astronomy. More... |
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Contact:
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Elżbieta Kuligowska Astronomical Observatory of the Jagiellonian University Elzbieta.Kuligowska [at] oa.uj.edu.pl |
