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MASTER Detection of the High Proper Motion Cool Dwarf

ATel #4053; V. Lipunov, D. Denisenko, V. Krushinsky, P. Balanutsa, V. Shumkov, E. Gorbovskoy, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, D. Zimnukhov (Moscow State University, SAI) I. Zalozhnih, A. Popov (Ural Federal University) K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress (Irkutsk State University) A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS) V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov (Blagoveshchensk Educational University), S. Shurpakov, P. Podvorotniy (MASTER team members), Hugo Levato and Carlos Saffe (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio; ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest (Observatorio Astronomico Felix Aguilar; OAFA)
on 19 Apr 2012; 13:25 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, Request for Observations, Star

MASTER-Tunka automatic system has detected a transient object at (RA, Dec) = 09h 39m 00.82s +39d 16m 10.6s on 2012 Apr. 14.650 UT which is not present on our reference images and DSS plates. The unfiltered object magnitude is 19.4m. The analysis of archival survey images and the data from various catalogs has shown the object to be a previously uncatalogued high proper motion star.

We have measured the position of the object on four DSS plates (POSS-II Infrared plate taken on 2000-02-05, POSS-II Blue of 1997-03-02, POSS-II Red of 1992-02-03 and POSS-I Red of 1953-02-08). In course of 47.0 years the object has moved by 29.5" in P.A.=142, corresponding to the proper motion of 0.63"/yr (385 and -495 mas/yr in R.A. and Decl., respectively). Our 2012 position is in line with these values.

The object is obviously identical to SDSS star SDSS J093900.46+391615.6 with the following ugriz magnitudes: 22.43(32), 20.35(2), 19.73(2), 19.45(2), 19.34(6). The object is not present in 2MASS catalog which means J>17.0 and (g-J)<2.5, thus excluding the possibility of it being a red dwarf. Based on the SDSS colors and magnitude, this object is most likely a cool white dwarf of DC type at the distance ~40 pc. In this case its tangential velocity would be ~120 km/s.

We have placed the SDSS g magnitude and proper motion of SDSS J093900.46+391615.6 on the diagram together with 112 cool SDSS white dwarfs from Kilic et al., 2006 (Astron. J., 131, 582). The image is available at http://observ.pereplet.ru/images/WD-pm_vs_SDSSg.gif

Spectroscopic confirmation is requested.

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