Video Experimental Relacionado
Updated: Apr 14, 2026

08:53
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
18.4K
Espectro infrarrojo de una enana blanca extremadamente fría
1Department of Physics and Astronomy, University of Leicester, UK. sth@ast.cam.ac.uk
Nature
|January 19, 2000
Resumen
Los astrónomos descubrieron la enana blanca más fría conocida, una estrella que se enfría durante miles de millones de años. Este hallazgo apoya la teoría de que estos restos estelares pueden constituir la Vía Láctea.
Área de la Ciencia:
- La astronomía y la astrofísica.
- Evolución Estelar Evolución Estelar
- Cosmología Cosmología.
Sus antecedentes:
- Las enanas blancas son restos estelares en etapa final formados por estrellas con masas iniciales por debajo de 8 masas solares.
- Estos objetos se enfrían durante miles de millones de años y se cree que comprenden una porción significativa del halo de materia oscura de la Vía Láctea.
- Detectar enanas blancas extremadamente frías es un desafío debido a su desvanecimiento y similitud espectral con otras estrellas enanas.
Objetivo del estudio:
- Para investigar la naturaleza y las propiedades de las enanas blancas extremadamente frías.
- Para probar modelos teóricos recientes que predicen un color más azul para estas estrellas.
- Para evaluar la contribución de las enanas blancas a la materia oscura galáctica.
Principales métodos:
- Adquisición y análisis de un espectro infrarrojo de una enana blanca extremadamente fría.
- Determinación de la temperatura de la estrella utilizando datos espectrales.
- Análisis cinemático para determinar la ubicación de la estrella dentro de la Vía Láctea.
Principales resultados:
- El espectro infrarrojo es consistente con los nuevos modelos que predicen enanas blancas más azules.
- Se determinó que la temperatura de la estrella era de 3.500 +/- 200 K, lo que la identifica como la enana blanca más fría conocida.
- La cinemática de la estrella la coloca en el halo de la Vía Láctea.
Conclusiones:
- El descubrimiento de esta fría enana blanca valida los modelos estelares actualizados.
- La densidad inferida de tales objetos apoya la hipótesis de que las enanas blancas dominan la materia oscura del halo de la Vía Láctea.
- Este hallazgo tiene implicaciones significativas para la comprensión de la composición galáctica y la distribución de la materia oscura.
Más Videos Relacionados
Videos de Conceptos Relacionados
Infrared (IR) Spectroscopy: Overview
7.6K
When electromagnetic radiation passes through a material, atoms or molecules transition from a lower to a higher energy state by absorbing radiation corresponding to the energy difference between the two states. The absorption of infrared (IR) radiation causes transitions between vibrational energy levels in a molecule. Therefore, IR spectroscopy is a useful analytical tool for determining the molecular structure of molecules.
Different compounds display unique properties due to their...
Different compounds display unique properties due to their...
7.6K
IR Spectrum
3.4K
When infrared (IR) radiation passes through a molecule, the bonds stretch or bend by absorbing the radiation. This absorption creates the molecule's absorption spectrum, which is the plot of its percentage transmittance versus wavenumber.
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0%...
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0%...
3.4K
IR Spectrum Peak Intensity: Amount of IR-Active Bonds
1.4K
When infrared radiation is passed through a molecule, absorption occurs if the molecule's vibration leads to a substantial change in its bond dipole moment. Transitions between vibrational energy levels, typically corresponding to infrared frequencies (4000–400 cm−1), allow absorption if the vibration significantly alters the dipole moment, making the molecule infrared active. The molecular bonds have different stretching and bending vibrations, resulting in various peaks with...
1.4K
IR Spectroscopy: Molecular Vibration Overview
6.5K
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
6.5K
IR Spectrometers
3.6K
There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR spectrometer, a beam of infrared radiation produced by a hot wire is divided into two parallel equal-intensity beams using mirrors. One beam passes through the sample, while another is a reference beam. The beams then move through the monochromator, which separates the radiations into a continuous spectrum of different frequencies. The...
3.6K
IR Spectrum Peak Intensity: Dipole Moment
2.0K
The dipole moment of a bond is the product of the partial charge on either atom and the distance between them. Dipole moments influence the efficiency of IR absorption and the peak intensity. When a bond with a dipole moment is placed in an electric field, the direction of the field determines if the bond is compressed or stretched. Electromagnetic radiation consists of an electric field component that rapidly reverses direction. It follows that polar bonds are alternately stretched and...
2.0K

