일본 아마추어천문가가 새로운 밝은 신성을 궁수자리에서 발견하다

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이번 주 내내 일기가 안 좋아서 이 글을 올리는 게 의미가 없을 것 같아 미뤄두다가
예상치 못한 때 관측을 가시는 회원 분들이 계셔서 혹시 그래도 도움이 될까 해서 올려봅니다.

아래 AAVSO 사이트에서의 신성의 차트를 올려드리니 참고하세요.
주말에 일기가 좋아야 할 텐데... 즐거운 별생활 되시기를...

New Bright Nova in Sagittarius
일본 아마추어천문가가 새로운 밝은 신성을 궁수자리에서 발견하다
                                                                       By: Bob King | October 24, 2016
 

궁수자리에서 새로운 신성이 일본 아마추어천문가에 의해 며칠 전 발견되었는데, 쌍안경으로 볼 수 있을 만큼 밝아졌다.

Look What the Pot Cooked Up
This map shows the sky facing southwest in late twilight for observers across the central U.S. and southern Europe. The 8th-magnitude nova (exaggerated here!) lies just above the spout of the Sagittarius Teapot, at R.A. 18h 10m 28.3s, Dec. –27° 29′ 59″.  It has been temporarily dubbed TCP J18102829-2729590 accordingly.         Stellarium

아슬아슬한 때 –적어도 북반구 관측자들에게- 밝은 신성이 궁수자리에서 발견되었다. 왜 아슬아슬하다고 하는가 하면 별자리가 박명후 남서쪽 하늘로 가라앉기 때문에, 북반구 중위도에서는 볼 수 있는 창을 단지 짧은 시간만 내어준다. 그러나 창이 있고, 이 놀라운 항성폭발의 광경을 볼 시간이 아직은 한동안 있다. 황혼이 끝난 직후에 봐야한다. 즉 여러분 지역의 해가 진 뒤에 한 시간 반 정도의 시간이 주어진다는 것을 의미한다.

A Deeper Look
I've labeled the two bright 'spout stars' in this more detailed map, which shows stars to about magnitude 9.5. This will get you very close. To continue to the nova, use the more detailed chart below.              Stellarium

잘 알려진 신성 사냥꾼인 이타가키라는 일본사람은 10월 20일에 신성“new star"을, 하늘-순찰 사진을 찍는 180mm telephoto lens로 잡아냈다. 그때는 단지 11등급이었다. 그러나 2일 안에, 그 별은 3등급이나 밝아졌고 지금은 8등급보다 더 밝다. 50mm쌍안경으로 잡을 수 있고 모든 망원경으로 볼 수 있다.

Nova by Way of Dolphin and Triangle
Use this final chart, which shows stars to about magnitude +10.5, to arrive at the nova. I've labeled a couple suggestive asterisms you can look for that will help you get there. North is up.                     Stellarium

일찍 나가서 최상을 모습을 잡자. 첫째, 화성을 활용하여 궁수자리를 찾아라. 그리고 주둥이 끝에 있는 두 개의 별에 초점을 맞추고 위의 지도를 사용해서 여러분의 방식으로 빽빽한 은하수 영역을 통해 신성을 정확히 지목하자. 단계단계 나아가자; 약간 시간이 걸릴 것이다. 그래봤자 별무리로 알려진 궁수자리이다. 

Takes Two to Tango
Novae occur in close binary systems where one star is a tiny but extremely compact white dwarf star. The dwarf pulls material into a disk around itself, some of which is funneled to the surface and ignites in a nova explosion.
Credit: NASA

모든 전형적인 신성들은 동반성에서 수소를 훔쳐가는 단단한 백색왜성으로 이루어진 가까운 이중성계이다. 가스는 결국에 왜성의 표면에 빨려들어가서, 왜성 표면에 쌓여간다. 중력에 의해 농축이 되고 수소융합이 촉발될 때까지 가열이 된다. 표층은 별을 싸고 있는 얇은 외피형태로 수소폭탄처럼 폭발한다. 이것이 신성을 볼 때 보이는 것이다 – 거대한폭탄이 터진다! 안에 있는 백색왜성은 멀쩡히 생존하고 다시 새로운 층을 자연스레 증대시키기 시작하고 최후에 다시 폭발할 것이다. 

물질들은 폭발하면서 우주공간에 초속 3000km의 엄청난 속도로 퍼진다. 희미하고 인지되지 않는 별이 몇 시간 안에 50,000에서 100,000배 까지 밝아져서, 여기 지구에서 누군가 쌍안경으로 찾을 수 있을 정도로 빛을 낸다. 놀랍다.

여러분은 AAVSO 웹사이트에 방문해서 밤마다 신성이 무엇을 하는지 추적할 수 있고, 신성의 임시이름, TCP J18102829-2729590,을 Pick a Star box(홈페이지의 오른쪽에 있음)칸에 적어 넣을 수 있다. 그리고 최근의 관측을 점검하고, 그들의 광곡선을 그리고, 자신의 차트를 만들 수 있다. AAVSO's Alert Notice는 최근의 등급평가를 포함해, 더 세세하게 기술되어 있다. (아래에 내용 첨부하였습니다.)    https://www.aavso.org/

행운이 있기를 그리고 신성이 어떻게 되가는지 알려주세요! 오늘밤 나는 볼 수가 없어요.

(원문)
New Bright Nova in Sagittarius
일본 아마추어천문가가 새로운 밝은 신성을 궁수자리에서 발견하다
                                                                       By: Bob King | October 24, 2016
 

A nova in Sagittarius, discovered a few nights ago by a Japanese amateur, has become bright enough to see in binoculars.

Just in the nick for time — at least for northern observers — a bright nova has been discovered in Sagittarius. I say nick of time because the constellation is sinking in the southwestern sky right after dusk, affording only a short viewing window from mid-northern latitudes. But a window it is, and there's still time to snatch a view of this amazing stellar explosion. Just make sure to look right after the end of twilight. That means about an hour and a half after your local sunset time.

Well-known nova hunter Koichi Itagaki of Japan nabbed the "new star" on October 20th, using a 180mm telephoto lens to take sky-patrol photos. At the time it was only about 11th magnitude. But within two days, the star shot up an additional three magnitudes and now shines brighter than 8.0. That puts it within range of 50mm binoculars and any telescope you might have.

Get out early for the best views. First, locate Sagittarius in the southwestern sky using Mars as your guide. Then focus on the two stars at the end of the spout and use the maps above to track your way through a dense Milky Way field to pinpoint the nova. Work step by step; it may take some time. It is Sagittarius after all, a constellation known for its stellar throngs.

All classical novae are close binary stars with a compact white dwarf stealing hydrogen from its companion. The gas ultimately funnels down to the surface of the dwarf, where its piles up on the star’s surface. It becomes compacted by gravity and heated until hydrogen fusion ignites. The layer explodes like a hydrogen bomb in the shape a thin shell enclosing the star. This is what you see when you look at a nova – a gigantic bomb going off! The underlying white dwarf survives intact, and begins accreting a new, fresh layer that will eventually explode again.

Material gets blasted into space at tremendous speeds of some 3,000 kilometers per second (6.2 million mph). A faint, unnoticed star brightens 50,000 to 100,000 times in a matter of hours, becoming luminous enough for someone back here on Earth to spot it in binoculars over the trees. Simply remarkable.

You can keep track of what the nova's doing night to night by visiting the American Association of Variable Star Observers (AAVSO) website and entering the nova's temporary name, TCP J18102829-2729590, in the Pick a Star box. You then have options to check recent observations, plot a light curve of them, or create a chart of your own. More details, including recent magnitude estimates, are the AAVSO's Alert Notice.

Good luck and let us know how the nova's doing! I can't wait to see it myself tonight.

출처
http://www.skyandtelescope.com/astronomy-news/observing-news/new-bright-nova-in-sagittarius/

2.Alert Notice 561: Nova in Sagittarius = ASASSN-16ma = PNV J18205200-2822100

October 28, 2016

Event: Nova in Sagittarius

Discovered by:
  - ASAS-SN (K. Z. Stanek (Ohio State University) et al.; ATel #9669)
  - Yukio Sakurai (Mito, Japan; via TOCP page)

Discovery magnitude:
  - ASAS-SN: V~13.7, using quadruple 14-cm "Cassius" telescope at CTIO
  - Sakurai: 10.4 unfiltered CCD, using Nikon D7100 digital camera + 180-mm f/2.8 lens

Discovery date:
  - ASAS-SN: 2016 October 25.02 UT
  - Sakurai: 2016 October 26.380 UT
 
Coordinates (2000.0): R.A. 18 20 52.25  Dec. -28 22 12.1  (from VSX)
 
Spectra: Spectroscopy indicating that ASASSN-16ma is a classical nova in the optically thick (Fe-curtain) stage was obtained 2016 Oct. 27.5 UT by P. Luckas (International Centre for Radio Astronomy Research, Univ. of Western Australia; ARAS Group; ATel #9678).

Observing recommendations: Observations of all types (visual, CCD, DSLR, spectroscopy) and all bands as instrumentation permits are strongly encouraged as the nova evolves.

Observations reported to the AAVSO:
 2016 Oct. 20.04 UT,  <17.3 V (ASAS-SN; Stanek et al., ATel #9669);
 23.398, <11.0 unfiltered CCD (Y. Sakurai, Mito, Japan; via TOCP page);
 25.02, 13.7: V +/-0.02 (ASAS-SN; Stanek et al., ATel #9669);
 26.02, 11.6: V +/-0.01 (ASAS-SN; Stanek et al., ATel #9669);
 26.05670, 11.76 B +/-0.07 (S. O'Connor, St. George, Bermuda);
 26.05750, 11.44 V +/-0.03 (O'Connor);
 26.05900, 11.44 CV +/-0.12 (O'Connor);
 26.48750, 11.0 (A. Pearce, Nedlands, W. Australia);
 27.0474, 11.04 B (S. Kiyota, Kamagaya, Japan; red color noted; with 0.50-m f/4.5 CDK astrograph + FLI-PL11002M at Mayhill, NM, USA remotely; via TOCP page);
 27.0474, 10.65 V (Kiyota, as above; red color noted);
 27.0474, 10.18 Ic (Kiyota, as above; red color noted);
 27.48890, 10.6 (Pearce);
 27.50153, 10.4 (D. Benn, Klemzig, S. Australia);
 27.95490, 10.3 (A. Amorim, Florianopolis, Brazil);
 28.49387, 10.3 (Benn);
 28.71389, 10.3 (D. Blane, Henley-on-Klip, South Africa);

Charts: Charts with a comparison star sequence for ASASSN-16ma may be created using the AAVSO Variable Star Plotter (VSP). Be sure to include the hyphen and no spaces in the name, as shown.

Submit observations: Please submit observations to the AAVSO International Database using the name ASASSN-16ma. Once a GCVS name is announced in an IAU Circular or CBET, please use that name.

Notes:
 a. Designated PNV J18205200-2822100 when posted to the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP). Most of the information in this Alert Notice is taken from the TOCP page or ATel #9669, #9678, #9680, and #9683.

b. Stanek et al. report no previous outbursts have been detected at the nova's location since ASAS-SN started observing the Galactic center in March 2016 (ATel #9669).

c. Position end figures
  - ASAS-SN (discovery, 2016 Oct. 25.02 UT): 52.12s, 13.52"
  - Sakurai (discovery, 2016 Oct. 26.380 UT): 52.00s, 10.0"
  - P. Mroz et al. for OGLE (2016 Oct. 27 UT; ATel #9683): 52.25s, 12.1"

d. Progenitor: R. K. Saito (Universidade Federal de Santa Catarina) et al. (ATel #9680) report a likely progenitor candidate is VVV J182052.14-282212.8, located at position end figures 52.141s, 12.79" (0.78 arcsec from the reported nova position). They also report that photometric flags in the VVV photometry as well as visual inspection of the images show the object may be a blend of two even fainter sources.

However, P. Mroz (Warsaw University Observatory) et al., on behalf of the OGLE team, conclude that the VVV star cannot be the progenitor, as measurement of OGLE images taken 2016 October 27 UT show it is 1.16 arcsec from the nova (ATel #9683). They also report the nova is not seen down to magnitude I=22 on the OGLE deep template image.

Congratulations to the ASAS-SN team and to Yukio Sakurai on this discovery!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen
출처
https://www.aavso.org/aavso-alert-notice-561