Coloquio IRyA esta semana/This week's colloquium at IRyA

[Sundar Srinivasan]

Hola (English version below),

Este jueves 20 de agosto a las 12:00, James Jackson del NRAO impartirá la plática:

"NH3 (1,1) Hyperfine Anomalies and the Structure of Molecular Clumps"

Resumen:

The 23.7 GHz ammonia (NH3) (1,1) inversion line is split into five hyperfine lines. Local Thermodynamic Equilibrium (LTE) suggests that the outer and inner pair of hyperfine lines should have exactly the same brightness. However, observations from the Australia Compact Telescope Array CAHCMC and the Green Bank Telescope RAMPS NH3 surveys of molecular clumps, show ubiquitous "hyperfine intensity anomalies," with typical intensity ratios RO/LO = 1.2 and LI/RI = 1.1. New MOLPOP radiative excitation models naturally reproduce the observed anomalies through selective radiative trapping of the overlapping far-infrared (2,1) - (1,1) hyperfine lines, but only if the linewidths are narrow (<0.8 km/s), much narrower than the observed linewidths (~2.0 km/s). Molecular clumps, therefore, must have narrow linewidths locally yet broad linewidths globally. These observations therefore rule out microturbulence (the same turbulent linewidths at all positions) in molecular clumps. Macroturbulence or large-scale flows are required to explain the observed hyperfine intensity anomalies.o 

Zoom link (Meeting ID: 890 9042 2717 Passcode: c0l0#qU1o)

Les pedimos que por favor:
1. Intenten conectarse ~10 minutos antes del mediodía, en caso de que haya algún problema.
2. Apaguen sus micrófonos y cámaras durante la presentación. Si estarán en el auditorio, apaguen sus celulares.
3. Reserven sus preguntas hasta el final de la presentación. Usen el botón "Raise Hand" en Zoom para hacer una pregunta, y el moderador tomará nota.
4. Mantengan abierta la ventana de chat de Zoom durante la sesión para que puedan recibir mensajes de los organizadores.

El café y las galletas estarán disponibles 15 min antes del coloquio. Traiga sus propias tazas y no traiga bebidas ni alimentos al auditorio.

Las diapositivas de la charla, así como el video, estarán disponibles en la página web del coloquio IRyA. Los videos también se pueden encontrar en nuestro canal de YouTube.

Saludos.

************************************************************************

Hi everyone,

On Thursday, the 20th of August at 12:00, James Jackson of NRAO will present the following talk:

"NH3 (1,1) Hyperfine Anomalies and the Structure of Molecular Clumps"

Abstract:

The 23.7 GHz ammonia (NH3) (1,1) inversion line is split into five hyperfine lines. Local Thermodynamic Equilibrium (LTE) suggests that the outer and inner pair of hyperfine lines should have exactly the same brightness. However, observations from the Australia Compact Telescope Array CAHCMC and the Green Bank Telescope RAMPS NH3 surveys of molecular clumps, show ubiquitous "hyperfine intensity anomalies," with typical intensity ratios RO/LO = 1.2 and LI/RI = 1.1. New MOLPOP radiative excitation models naturally reproduce the observed anomalies through selective radiative trapping of the overlapping far-infrared (2,1) - (1,1) hyperfine lines, but only if the linewidths are narrow (<0.8 km/s), much narrower than the observed linewidths (~2.0 km/s). Molecular clumps, therefore, must have narrow linewidths locally yet broad linewidths globally. These observations therefore rule out microturbulence (the same turbulent linewidths at all positions) in molecular clumps. Macroturbulence or large-scale flows are required to explain the observed hyperfine intensity anomalies.

Zoom link (Meeting ID: 890 9042 2717 Passcode: c0l0#qU1o)

We request that you please:
1. Attempt to connect ~10 min before noon, in case there are any issues.
2. Turn off your mics and cameras during the presentation. If you'll be in the auditorium, please turn off your cellphones.
3. Reserve your questions till the end of the presentation. Use the "Raise Hand" button in Zoom to ask a question, and the moderator(s) will make a note.
4. Have your Zoom chat window open during the session so you are able to receive messages from the moderator(s).

Coffee and cookies will be available 15 min prior to the colloquium. Please bring your own mugs, and please do not bring beverages or food into the auditorium.

Slides from the talk, as well as the video, will be available on the IRyA colloquium webpage. The videos can also be found on our YouTube channel.

Cheers,

Ramandeep y Sundar