Astronomía: La misión Planck, de la ESA, detecta una misteriosa neblina de microondas cerca del centro de la galaxia

Hola amigos: A VUELO DE UN QUINDE EL BLOG., La misión de la ESA Planck ha revelado que nuestra galaxia contiene islas de aire frío que no habían sido descubiertas previamente, así como una misteriosa neblina de microondas. Estos resultados proporcionan a los científicos nuevos datos con los que investigar, y les sitúa más cerca de comprender el plano de construcción de las estructuras cósmicas.

This all-sky image shows the distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck (blue).

A compilation of previous surveys (Dame et al. (2001)), which left large areas of the sky unobserved, has been superimposed for comparison (red). The outlines identify the portions of the sky covered by these surveys. Molecular clouds, dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck.

The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently. The most important of these tracers is CO, which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI).

Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud. The Planck image represents the first all-sky map of CO ever compiled.

As highlighted in this image, the largest CO surveys thus far have concentrated on mapping the full extent of the Galactic Plane, where most clouds are concentrated, leaving large areas of the sky unobserved.

The CO map compiled with Planck shows concentrations of molecular gas in portions of the sky that have not been observed before, such as at high galactic latitudes, where clouds that are relatively close to the Solar System might be projected on the all-sky map. Planck's high sensitivity to CO also means that even very low-density clouds can be detected, and new details can be revealed in clouds that were already known.

Follow-up observations and further studies of these stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck Collaboration; T. Dame et al., 2001

This image shows the Cepheus molecular cloud complex as seen through the glow of carbon monoxide (CO) with Planck (blue). The same region is shown as imaged by previous CO surveys (Dame et al., 2001) for comparison (red). Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck.

The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently.

The most important of these tracers is carbon monoxide (CO), which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud like the Cepheus complex.

The Cepheus region is one of those which has been thoroughly observed from ground-based observatories. A comparison to the equivalent Planck map shows that: (a) all the large-scale features imaged from the ground are well-reproduced by Planck; (b) the high sensitivity and homogeneous mapping made by Planck reveals new details at small scales.

Follow-up observations and further studies of this and other stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck Collaboration; T. Dame et al., 2001 This all-sky image shows the distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck. The inserts provide a zoomed-in view onto three individual regions on the sky where Planck has detected concentrations of CO: Cepheus, Taurus and Pegasus, respectively. Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck.

The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently.

The most important of these tracers is CO, which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud.

This is the first all-sky map of CO ever compiled. The largest CO surveys thus far have concentrated on mapping the full extent of the Galactic Plane, where most clouds are concentrated, leaving large areas of the sky unobserved. The all-sky CO map compiled with Planck data shows concentrations of molecular gas in portions of the sky that had never before been surveyed.

For example, many regions at high galactic latitude, such as the Pegasus region, had not been covered by the CO survey compiled by Dame et al. (2001). Planck's high sensitivity to CO also means that even very low-density clouds can be detected, as in the case of the Pegasus clouds. The Cepheus and Taurus molecular cloud complexes had already been surveyed for CO, but the images obtained from Planck data allow astronomers to study the cloud structure in greater detail than allowed by previous surveys. Follow-up observations and further studies of these stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck Collaboration

This all-sky image shows the spatial distribution over the whole sky of the Galactic Haze at 30 and 44 GHz, extracted from the Planck observations. In addition to this component, other foreground components such as synchrotron and free-free radiation, thermal dust, spinning dust, and extragalactic point sources contribute to the total emission detected by Planck at these frequencies.

The prominent empty band across the plane of the Galaxy corresponds to the mask that has been used in the analysis of the data to exclude regions with strong foreground contamination due to the Galaxy's diffuse emission. The mask also includes strong point-like sources located over the whole sky.

The Galactic Haze is seen to be distributed around the Galactic Centre and its spectrum is similar to that of synchrotron emission. However, compared to the synchrotron emission seen elsewhere in the Milky Way, the Galactic Haze has a 'harder' spectrum, meaning that its emission does not decline as rapidly with increasing frequency. Diffuse synchrotron emission in the Galaxy is interpreted as radiation from highly energetic electrons that have been accelerated in shocks created by supernova explosions. Several explanations have been proposed for the unusual shape of the Haze’s spectrum, including enhanced supernova rates, galactic winds and even annihilation of dark-matter particles. Thus far, none of them have been confirmed and the issue remains open.

Credits: ESA/Planck Collaboration
This all-sky image shows the distribution of the Galactic Haze seen by ESA's Planck mission at microwave frequencies superimposed over the high-energy sky as seen by NASA's Fermi Gamma-ray Space Telescope.

The Planck data (shown here in red and yellow) correspond to the Haze emission at frequencies of 30 and 44 GHz, extending from and around the Galactic Centre. The Fermi data (shown here in blue) correspond to observations performed at energies between 10 and 100 GeV and reveal two bubble-shaped, gamma-ray emitting structures extending from the Galactic Centre.

The two emission regions seen by Planck and Fermi at two opposite ends of the electromagnetic spectrum correlate spatially quite well and might indeed be a manifestation of the same population of electrons via different radiation processes. Synchrotron emission associated with the Galactic Haze seen by Planck exhibits distinctly different characteristics from the synchrotron emission seen elsewhere in the Milky Way.

Diffuse synchrotron emission in the Galaxy is interpreted as radiation from highly energetic electrons that have been accelerated in shocks created by supernova explosions. Compared to this well-studied emission, the Galactic Haze has a 'harder' spectrum, meaning that its emission does not decline as rapidly with increasing frequency.

Several explanations have been proposed for this unusual behaviour, including enhanced supernova rates, galactic winds and even annihilation of dark-matter particles. Thus far, none of them have been confirmed and the issue remains open. The Planck image includes the mask that has been used in the analysis of the data to exclude regions with strong foreground contamination due to the Galaxy's diffuse emission. The mask also includes strong point-like sources located over the whole sky.

Credits: ESA/Planck Collaboration (microwave); NASA/DOE/Fermi LAT/D. Finkbeiner et al. (gamma rays)

This all-sky image shows the distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck (blue). A compilation of previous surveys (Dame et al. (2001)), which left large areas of the sky unobserved, is shown for comparison (red).

Molecular clouds, dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck. The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born.

Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently. The most important of these tracers is carbon monoxide (CO), which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers.

But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud. The Planck image represents the first all-sky map of CO ever compiled. As highlighted in this image, the largest CO surveys thus far have concentrated on mapping the full extent of the Galactic Plane, where most clouds are concentrated, leaving large areas of the sky unobserved.

The CO map compiled with Planck shows concentrations of molecular gas in portions of the sky that have not been observed before, such as at high galactic latitudes, where clouds that are relatively close to the Solar System might be projected on the all-sky map.

Planck's high sensitivity to CO also means that even very low-density clouds can be detected, and new details can be revealed in clouds that were already known. Follow-up observations and further studies of these stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck Collaboration; T. Dame et al., 2001 This all-sky image shows the distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck. Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck.

The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently.

The most important of these tracers is carbon monoxide (CO), which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud. This is the first all-sky map of CO ever compiled.

The largest CO surveys thus far have concentrated on mapping the full extent of the Galactic Plane, where most clouds are concentrated, leaving large areas of the sky unobserved. The CO map compiled with Planck shows concentrations of molecular gas in portions of the sky that have not been observed before, such as at high galactic latitudes, where clouds that are relatively close to the Solar System might be projected on the all-sky map.

Planck's high sensitivity to CO also means that even very low-density clouds can be detected, and new details can be revealed in clouds that were already known. Follow-up observations and further studies of these stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck CollaborationThis image shows the Taurus molecular cloud complex as seen through the glow of carbon monoxide (CO) with Planck (blue). The same region is shown as imaged by previous CO surveys (Dame et al., 2001) for comparison (red).

Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck. The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently. The most important of these tracers is carbon monoxide (CO), which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud like the Taurus complex.

The all-sky CO map compiled with Planck data shows concentrations of molecular gas in portions of the sky that had never before been surveyed. Planck's high sensitivity to CO also means that even very low-density clouds can be detected, and new details can be revealed in clouds that were already known.

This can be seen by comparing the two images of the Taurus cloud: the Planck image allows astronomers to study the cloud structure in greater detail. Follow-up observations and further studies of this and other stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation.

Credits: ESA/Planck Collaboration; T. Dame et al., 2001 This image shows molecular clouds in the Pegasus region as seen through the glow of carbon monoxide (CO) with Planck (blue). Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck.

The vast majority of gas in these clouds consists of molecular hydrogen (H2), and it is in these cold regions that stars are born. Since cold H2 does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently. The most important of these tracers is carbon monoxide (CO), which emits a number of rotational emission lines in the frequency range probed by Planck's High Frequency Instrument (HFI). Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright that they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud like those in the Pegasus region. The all-sky CO map compiled with Planck data shows concentrations of molecular gas in portions of the sky that had never before been surveyed. For example, many regions at high galactic latitude, such as the Pegasus region, had not been covered by previous CO surveys. Planck's high sensitivity to CO also means that even very low-density clouds can be detected, as in the case of the Pegasus clouds. Follow-up observations and further studies of this and other stellar nurseries will allow a detailed investigation of the physical and chemical conditions that lead to the formation of molecular clouds, shedding new light on the very early phases of star formation. Credits: ESA/Planck Collaboration.

La misión de la ESA Planck ha revelado que nuestra galaxia contiene islas de aire frío que no habían sido descubiertas previamente, así como una misteriosa neblina de microondas. Estos resultados proporcionan a los científicos nuevos datos con los que investigar, y les sitúa más cerca de comprender el plano de construcción de las estructuras cósmicas. Los resultados, en esta fase intermedia de la misión Planck, están siendo dados a conocer esta semana en una conferencia internacional en Boloña, Italia, a la que asisten astrónomos de todo el mundo.
Estos resultados incluyen el primer mapa de distribución de monóxido de carbono que cubre todo el cielo. El monóxido de carbono es un ingrediente de las nubes frías presentes en la Vía Láctea y en otras galaxias. Estas nubes, integradas fundamentalmente por moléculas de hidrógeno, constituyen los reservorios a partir de los cuales nacen estrellas.
Sin embargo, las moléculas de hidrógeno son difíciles de detectar porque apenas emiten radiación. El monóxido de carbono se forma en condiciones similares y, aunque es mucho más raro, emite luz más fácilmente y por tanto se detecta mejor. Los astrónomos lo usan como indicador de la presencia de nubes de hidrógeno.
“Planck resulta ser un detector excelente de monóxido de carbono en todo el cielo”, dice Jonathan Aumont, del Institut d’Astrophysique Spatiale, Universite Paris XI, en Orsay, Francia.
Las observaciones de monóxido de carbono llevadas a cabo con radiotelescopios en tierra requieren mucho tiempo de observación, y por tanto se limitan a las regiones del cielo en las que se sabe que existen –o se espera que existan- nubes moleculares.
“La gran ventaja de Planck es que barre todo el cielo, y nos permite detectar concentraciones de gas molecular donde no esperábamos encontrarlas”, dice Aumont.
Planck ha detectado también una misteriosa neblina de microondas que por ahora constituye un misterio.
Procede de la región en torno al centro galáctico, y parece ser radiación de tipo sincrotrón. Esta radiación se produce cuando los electrones atraviesan campos magnéticos tras haber sido acelerados en explosiones de supernovas.
Lo curioso es que la radiación sincrotrón que aparece asociada a la misteriosa neblina galáctica tiene características diferentes de la emisión sincrotrón que se detecta en otros lugares de la Vía Láctea.
La niebla galáctica muestra lo que los astrónomos llaman un espectro más duro: su emisión no disminuye tan rápidamente a medida que la energía aumenta.
Han sido propuestas varias explicaciones para este extraño comportamiento, incluyendo más supernovas de lo habitual, vientos galácticos e incluso la aniquilación de partículas de materia oscura.
Pero hasta ahora ninguna de ellas ha podido ser demostrada.
“Los resultados sobre la niebla galáctica y la distribución del monóxido de carbono obtenidos hasta ahora por Planck nos proporcionan una nueva visión sobre procesos muy interesantes que tienen lugar en nuestra galaxia”, dice Jan Tauber, Jefe Científico de Planck, de la ESA.
El principal objetivo de Planck es observar la Radiación de Fonde Cósmico de Microondas (CMB) -la luz fósil del Big Bang-, y analizar la información que contiene acerca de los ingredientes del universo y del origen de las estructuras cósmicas.
Pero este objetivo solo puede ser alzanzado cuando hayan sido identificadas, y eliminadas, todas las fuentes de emisión más próximas en el tiempo, como la neblina galáctica y la señal del monóxido de carbono.
“La laboriosa y delicada tarea de eliminar la emisión de fuentes próximas nos proporciona datos muy valiosos sobre temas candentes tanto en astronomía galáctica como extragaláctica”, dice Tauber.
“Esperamos caracterizar esta emisión y después analizar la radiación de fondo de microondas con un detalle sin precedentes”, prosigue.
Los primeros resultados de Planck relativos al origen y la evolución del universo serán publicados en 2013. ESA.
Guillermo Gonzalo Sánchez Achutegui
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