공생별 AG Peg는 적색거성(GS)과 백색왜성(WD)으로 구성된 성운으로 둘러싸인 쌍성계이다. AG Peg의 분광 자료는 1998년, 2001년, 그리고 2002년의 세 시기에 미국 Lick 천문대에서 관측한 자료로 HI 발머 방출선 자료를 분 석하였다. AG Peg의 선세기와 폭은 각 시기에 따라 변하는데, Hα와 Hβ선에서 모두 청색편이, 적색편이, 넓은 폭 성 분이 나타났다. 가스 성운의 운동학적 특성을 보여주는 방출선은 WD주변에 형성된 강착원반의 반경이 매우 큼을 보여 준다. 관측자의 시선 방향을 고려하면, 1998년 관측은 AG Peg의 GS와 WD가 나란히 하늘에 있는 반면, 2002년에는 WD가 GS의 전면에, 2001년에는 WD가 GS의 뒷면에 위치하였다. 이러한 상대적인 위치와 분광선의 변화를 고려하여, 우리는 GS에서 WD로의 가스유입이 지속적으로 이루어지고, 그 결과 형성된 두꺼운 원반의 회전이 관측된 분광선 윤 곽의 형성을 가져온 것으로 결론지었다.

The missing historical record of the Cassiopeia A (Cas A) supernova (SN) event implies a large extinction to the SN, possibly greater than the interstellar extinction to the current SN remnant. Here we investigate the possibility that the guest star that appeared near Cas A in 1592{1593 in Korean history books could have been an `impostor' of the Cas A SN, i.e., a luminous transient that appeared to be a SN but did not destroy the progenitor star, with strong mass loss to have provided extra circumstellar extinction. We rst review the Korean records and show that a spatial coincidence between the guest star and Cas A cannot be ruled out, as opposed to previous studies. Based on modern astrophysical ndings on core-collapse SN, we argue that Cas A could have had an impostor and derive its anticipated properties. It turned out that the Cas A SN impostor must have been bright (MV = - 14:72:2 mag) and an amount of dust with visual extinction of ≥ 2:8  2:2 mag should have formed in the ejected envelope and/or in a strong wind afterwards. The mass loss needs to have been spherically asymmetric in order to see the light echo from the SN event but not the one from the impostor event.

We present photometric results of the  Sct star V1162 Ori, which is extensively monitored for a total of 49 nights from mid-December 2014 to early-March 2015. The observations are made with three KMTNet (Korea Microlensing Telescope Network) 1.6 m telescopes installed in Chile, South Africa, and Australia. Multiple frequency analysis is applied to the data and resulted in clear detection of seven frequencies without an alias problem: five known frequencies and two new ones with small amplitudes of 1.2-1.7 mmag. The amplitudes of all but one frequency are significantly different from previous results, confirming the existence of long-term amplitude changes. We examine the variations in pulsation timings of V1162 Ori for about 30 years by using the times of maximum light obtained from our data and collected from the literatures. The O − C (Observed minus Calculated) timing diagram shows a combination of a downward parabolic variation with a period decreasing rate of (1/P)dP/dt = −4.22 × 10−6 year−1 and a cyclic change with a period of about 2780 days. The most probable explanation for this cyclic variation is the light-travel-time effect caused by an unknown binary companion, which has a minimum mass of 0.69 M⊙. V1162 Ori is the first  Sct-type pulsating star of which the observed fast period decrease can be interpreted as an evolutionary effect of a pre-main sequence star, considering its membership of the Orion OB 1c association.

Some asteroid specimens were collected at a depth of 150 m near Moseulpo in Jeju Island, Korea using fishing nets on October 2014. The specimens were identified as Henricia pacifica Hayashi, 1940 belonging to the family Echinasteridae of order Spinulosida. In the Korean fauna, seven species of genus Henricia were reported of which two species, H. nipponica and H. ohshimai, were distributed in Jeju Island. The morphological characteristics of this species were re-described with illustrations.