Japanese version Home Page Updated on April 19, 1999
April 3, 1999
New variable stars (MisV0001-0004)
MISAO Project Announce Mail (Apr. 19, 1999)
Hello. I am Seiichi Yoshida working on the MISAO project.
After the announcement on Apr. 3 about our first new variable star MisV0001, Seiichiro Kiyota sent me his observations of this object in past. Here I introduce you the whole behavior of the brightness including the further observations by the Ageo Survey team.
In addition, Masayuki Suzuki reported that this object is found on the Real Sky image taken on May 3, 1987, as a very faint star.
These observations imply that MisV0001 varies between 14 mag and 17.5 mag by CCD with roughly 1-year period. It was discovered just when it was brightening rapidly in late March, 1999.
After the discovery of MisV0001, three more new variable stars have been discovered.
Code R.A. (J2000.0) Decl. Max Min ID ------------------------------------------------------------ MisV0001 175226.59 -174000.7 14.1C 16.9C MisV0002 072403.56 +412602.0 13.3C 14.7C GSC2965.0210 USNO1275.06972791 MisV0003 175244.93 -172401.4 12.5C 13.4C MisV0004 175313.59 -172844.2 12.1C 13.3C
Two of the three, MisV0003 and MisV0004 are also discovered on the images of Sakurai's V4334 Sgr and MisV0001. The distance from V4334 Sgr is about 2 arcmin (MisV0001), about 17 arcmin (MisV0003) and about 16 arcmin (MisV0004). It means three new variable stars were discovered by searching such a small area for only about two months.
Mira type variable stars can be about two or three mag brighter by CCD than by photo or visually. Therefore, many faint variable stars whose peak brightness is 14-16 mag visually, which have been unknown, can be detected bright and discovered by CCD, I guess.
MisV0002 was detected from the 300-mm camera lens or 18-cm reflector images of Comet 52P/Harrington-Abell taken between Dec. 9 and 20, 1998, by KenIchi Kadota, Ageo City, Saitama, Japan. The magnitude estimated by the PIXY system show that this object is about one mag fainter than usual on Dec. 17. Because it is as bright as usual on the next day, it is probably an eclipsing binary.
Furthermore, another variable star brightening from 10.5 mag to 8.3 mag at R.A. 17h59m48s.2, Decl. -31o16'03" was detected from the Ageo Survey images.
1999 Jan. 29 10.5 mag Feb. 20 8.4 mag Mar. 12 8.3 mag
Here is the search result of known variable stars.
V1725 SGR 93.2" V1725 SGR R.A.=17 59 41.30 Decl.=-31 16 32.4 13.0 - <15.2 mag (P) type:M Epoch=28415 Period=380 Sp:M7 IRAS 17565-3115 7.9" IRAS 17565-3115 R.A.=17 59 47.60 Decl.=-31 16 05.0 (41 x 7", p.a.=91) flux(12)=26.49 flux(25)=11.61 flux(60)=2.09 flux(100)=<15.18 93% variable
The position recorded in the GCVS is 1.5 arcmin far away from the detected position. However, there is no star detected at the position in the GCVS. So this variable star is V1725 Sgr. This case made it clear that the position of V1725 Sgr in the GCVS was inaccurate.
-- Seiichi Yoshida firstname.lastname@example.org http://www.info.waseda.ac.jp/muraoka/members/seiichi/index.html