Apr. 17 Mon  14:30-15:30     ALMA-J seminar  Zoom / ALMA building #102 (hybrid) 

Apr. 18 Tue   10:00-11:30     太陽系小天体セミナー    Zoom 

Apr. 19 Wed  10:30-12:00    SOKENDAI Colloquium   Zoom / the large seminar room (hybrid) 

Apr. 19 Wed  14:30-15:30     ALMA-J seminar  Zoom / ALMA building #102 (hybrid) 

Apr. 19 Wed  15:30-17:00     NAOJ Science Colloquium  Zoom / the large seminar room (hybrid) 

Apr. 21 Fri    16:00-17:00     NAOJ Seminar      Zoom / Large Seminar Room (hybrid)


“2023.4.17-2023.4.23” の続きを読む


Apr. 10 Mon  15:00-16:30     Solar and Space Plasma Seminar  Zoom / Insei Seminar Room (hybrid) 

Apr. 11 Tue   10:00-11:30     太陽系小天体セミナー    Zoom 

Apr. 12 Wed  15:30-17:00     NAOJ Science Colloquium  Zoom / the large seminar room (hybrid) 

Apr. 14 Fri    16:00-17:00     NAOJ Seminar      Zoom / Large Seminar Room (hybrid)


“2023.4.10-2023.4.16” の続きを読む


Mar. 22 Wed   11:00-12:00   NAOJ Seminar         Zoom / Large Seminar Room(hybrid)

Mar. 22 Wed   14:30-15:30   ALMA-J seminar        Zoom / ALMA building #102 (hybrid)

Mar. 22 Wed   15:30-17:00   NAOJ Science Colloquium   Zoom / Instrument Development Bldg. 3 (hybrid)

Mar. 22 Wed   16:00-17:00   NAOJ Seminar         Zoom / Large Seminar Room(hybrid)


“2023.3.20-2023.3.26” の続きを読む


Feb. 27 Mon   15:30-17:00     Solar and Space Plasma Seminar  Zoom

Feb. 28 Tue    10:00-11:30     太陽系小天体セミナー     Zoom

Feb. 28 Tue   16:00-17:00     NAOJ Seminar      Zoom/Lecture Room(hybrid)

Mar. 1  Wed    14:30-15:30     ALMA-J Seminar    Zoom/ALMA building #102 (hybrid)

Mar. 1  Wed    15:30-17:00     NAOJ Science Colloquium   Zoom / Instrument Development Bldg. 3 (hybrid)


=============== Feb 27 Mon ===============

Campus: Mitaka
Seminar: Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic: Scheduled
Date and time:2月27日 (月), 15:30-17:00
Place: Zoom

-Name:Takayoshi oba

-Comment:in English

=============== Feb 28 Tue ===============


タイトル:2017年 京都火球と潜在的に危険な地球接近二重小惑星 2003 YT1
Abstract:We present a fireball detected in the night sky over Kyoto,
Japan on UT 2017 April 28 at 15h 58m 19s by the SonotaCo Network. The
absolute visual magnitude is Mv=−4.10±0.42mag. Luminous light curves
obtain a meteoroid mass m=29±1g, corresponding to the size
a_s=2.7±0.1cm. Orbital similarity assessed by D-criterions (cf.
D_SH=0.0079) has identified a likely parent, the binary near-Earth
asteroid (164121) 2003 YT1. The suggested binary formation process is
a YORP-driven rotational disintegration. The asynchronous state
indicates the age of < 1e4yr, near or shorter than the upper limit to
meteoroid stream lifetime. We examine potential dust production
mechanisms for the asteroid, including rotational instability,
resurfacing, impact, photoionization, radiation pressure sweeping,
thermal fracture and sublimation of ice. We find some of them capable of
producing the meteoroid-scale particles. Rotational instability is
presumed to cause mass shedding, in consideration of the recent
precedents, possibly releasing mm-cm scale dust particles. Impacts by
micrometeorites with size≃1mm could be a trigger for ejecting the
cm-sized particles. Radiation pressure can sweep out the mm-sized dust
particles, while not sufficient for the cm-sized. For the other
mechanisms, unprovable or unidentified. The feasibility in the parental
aspect of 2003 YT1 is somewhat reconciled with the fireball observation,
yielding an insight into how we approach potentially hazardous objects.

Kasuga, Sato, Ueda, Fujiwara, Tsuchiya and Watanabe (2020), AJ, 159, 47


=============== Feb 28 Tue ===============

Seminar:NAOJ Seminar
Regularly Scheduled/Sporadic:Sporadic
Date and time:2023 February 28, 16:00-17:00
Place: Zoom/Lecture Room(hybrid)
Speaker:Shi Dai
Affiliation:Western Sydney University
Title:Magnetic Field Reversal around
an Active Fast RadioBurst
Abstract:The environment of actively repeating fast radio bursts (FRBs) has been shown to be complex and varying. The recently localized FRB 20190520B is extremely active, has the largest confirmed host dispersion measure (DM), and is only the second FRB source associated with a compact, persistent radio source (PRS). The main tracer of the magneto-ionic environments is the rotation measure (RM), a path-integral of the line-of-sight component of magnetic field strength (B) and electron density, which does not allow a direct probe of the B-field configuration. Here we report direct evidence for a B-field reversal based on the observed sign change and extreme variation of FRB 20190520B’s RM, which changed from +10000 rad/m^2 to -16000 rad/m^2 between June 2021 and January 2022. Such extreme RM reversal has never been observed before in any FRB nor in any astronomical object. The implied short-term change of the B-field configuration in or around the FRB could be due to the vicinity of massive black holes, a magnetized companion star in binary systems, or a young supernova remnant along the line of sight.

-Name:Fujii, Yuka

=============== Mar 1 Wed ===============

Seminar:ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: March 1, 2023 (Wed), 14:30 – 15:30
Place: ALMA building #102 / Zoom (hybrid)

Speaker : Hanae Inami and Hiddo Algera
Affiliation: Hiroshima University and NAOJ/Hiroshima University
Title: An ALMA Systematic Survey of Distant Galaxies: Obscured Star Formation at z~7
In recent years, many massive galaxies have been discovered when the Universe was only 1Gyr old or younger. This raises the question of how so much mass was assembled in such a short time. In particular, some of these galaxies are dust rich, suggesting that dust is also being produced in a rapid manner in the early universe. Taking advantage of ALMA’s capability of efficient spectroscopic searches for galaxies at z > 6.5, we have conducted an ALMA Cycle-7 Large Program, REBELS (Reionization Era Bright Emission Line Survey) to perform a systematic study of the interstellar medium (ISM) in 40 UV-selected galaxies at z > 6.5. The design of this survey has allowed us to spectroscopically confirm 23 galaxies in the Epoch of Reionization, as well as detect dust continuum in 14 galaxies, increasing the number of known dusty galaxies at z > 6.5 by a factor of three. In this talk, we will first present an outline of the REBELS program and then focus on discussing recent results from the dust continuum detections. We will present 1) the typical fraction of obscured star formation in UV-selected galaxies at z~7, and 2) new constraints on the dust-obscured cosmic star formation rate density in the epoch of reionization. In addition, we have conducted follow-up observations with ALMA to cover shorter wavelengths in several REBELS galaxies. We will present recent results on the shape of the infrared spectral energy distribution in three z~7 galaxies, and discuss their dust temperatures, masses and ISM properties in the context of the known high-redshift population.

Facilitator: Shun Ishii, Jorge Zavala

=============== Mar 1 Wed ===============

Seminar:NAOJ Science Colloquium
Regularly Scheduled/Sporadic:Every Wednesday
Date and time:2023 March 1, 15:30-17:00
Place:zoom / Instrument Development Bldg. 3 (hybrid)

Speaker:Mizutani Yohsuke
Affiliation:NAOJ (M2)

Speaker:Hatano Shun
Affiliation:NAOJ (M1)

-Name:Akimasa Kataoka