Seminars

The UHH Research Park includes the headquarters for the East Asian Observatory, the Caltech Submillimeter Observatory, Subaru, Gemini, UKIRT, the Smithsonian Submillimeter Array and the Institute for Astronomy, plus the astronomers at the University of Hawaii at Hilo. We are one of the major centres for astronomy in the world and encourage all visitors to the JCMT to take advantage of the proximity of these institutes, and give a seminar while in Hilo. Your talk will be advertised at each of the above institutes.


Upcoming Seminar: Feb 27th, 2019, 2pm (HST)

Location: EAO Office, Hilo

Hongjun Ma, Purple Mountain Observatory, Chinese Academy of Sciences

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Upcoming Seminar: March 5th, 2019, 2pm (HST)

Absorption Lines as a Possible Probe of Protoplanetary Disk Wind

Location: EAO Office, Hilo

Ziyan Xu, Kavli Institute for Astronomy and Astrophysics

The evolution and dispersal of protoplanetary disks play an important role in planet formation, and are driven by angular momentum transport and mass loss due to disk winds. The angular momentum transport is largely driven by faster magnetized disk wind, while disk mass loss is conventionally considered dominated by slower photoevaporative wind due to high-energy radiation from the central star. Both magnetized and photoevaporative winds have been detected and in most of the cases, the mass flux is measured through analysis of emission lines, and mass loss rates remain uncertain. Absorption lines offer a powerful complement to emission lines, by sampling the wind in our line-of-sight to the emission region. In this talk, I will present an observational analysis of wind absorption in far-ultraviolet stellar spectral lines. I will first present our survey of T Tauri stars by STIS and COS on HST, including C II 1335 doublets and a few other lines. By characterizing CII 1335 doublets, we estimate wind properties including C II column density and wind velocities for components that are considered related to magnetized wind and photoevaporative wind seperately. We then compare our observational results to stellar and disk properties and discuss the implication of our results. I will also present interpretations by forward-modeling wind absorption assuming photoevaporative wind and magneto-photoevaporative wind. I will show that in order to better understand the line profiles, magneto-photoevaporative wind is needed instead of the conventional scenario of pure photoevaporative wind. Our observational results including wind velocity and absorber column density provide potential constraints to mass loss rates.

Upcoming Seminar: March 13th, 2019, 2pm (HST)

An Extraordinary Submillimeter Flare in a T Tauri Binary System

Location: EAO Office, Hilo

Steve Mairs, EAO

The binary T Tauri system JW 566 in the Orion Molecular Cloud underwent an energetic, short-lived flare observed at 450 and 850 miconrs by SCUBA-2 on 2016 November 26 (UT). The emission faded by nearly 50% during the 31 minute integration. The 850 μm flux corresponds to a radio luminosity of Lν =8× 1019 erg s-1 Hz-1, approximately one order of magnitude brighter (in terms of νLν ) than that of a flare of the young star GMR-A, detected in Orion in 2003 at 3mm. The event may be the most luminous known flare associated with a young stellar object and is also the first coronal flare discovered at submillimeter wavelengths. We interpret this event to be a magnetic reconnection that energized charged particles to emit gyrosynchrotron/synchrotron radiation.

Upcoming Seminar: May 3rd, 2019, 2pm (HST)

Dust and Molecular gas in Early-Type Galaxies

Location: EAO Office, Hilo

Anne Sansom, University of Central Lancashire

Elliptical and lenticular (E/SO) galaxies, collectively known as ETGs, are traditionally thought to be red and dead. However, there is evidence of some cool gas and dust, sometimes seen in absorption as dust lanes in optical images. For late-type galaxies there is a link between the presence of molecular gas and dust, with dust arising mainly from red giant stars and molecular gas and dust forming the sites of the next generation of stars. However, it is less clear how the dust and gas arrived in ETGs. Complete samples are needed to get a clearer picture of the cool ISM properties in E/S0 galaxies. Large surveys with the Herschel Space Observatory gave us the data to look at complete samples of galaxies. We combined data from two such surveys with multi-waveband data from the GAMA survey to uncover the dust properties in ETGs as a function of galaxy characteristics. We show the properties of these dusty ETGs in this talk. Recent follow-on observations with ALMA, for a small sub-sample of these dusty ETGs, will also be presented in this talk, highlighting their molecular gas content and the variety of cool interstellar media found in ETGs.


Where and How:

EAO seminars are (usually) held in the second floor conference room at the East Asia Observatory, 660 N. A’ohoku Place, Hilo, Hawaii. Please note that access to EAO is possible only through the main entrance (through the side doors facing Subaru).

If you would like to view the seminar via Polycom or Zoom, please contact the helpdesk well in advance of the talk and we will make sure that the option it available. Polycom contact details or Zoom meeting information will be made available on request.

The EAO phone number is: (808) 961-3756. A full list of past seminar speakers can be found below for the current and previous years. These pages also contain links to PDF copies of the seminar slides and other materials, where available.

To join the Seminar e-mail list:

EAO Seminars are sent out via eao_seminar@eao.hawaii.edu. If you wish to join this seminar list please send an e-mail to eao_seminar-join@eao.hawaii.edu.

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