Star formation in the “Gulf of Mexico”

Abstract

We present an optical/infrared study of the dense molecular cloud, L935, dubbed "The Gulf of Mexico", which separates the North America and the Pelican nebulae, and we demonstrate that this area is a very active star forming region. A wide-field imaging study with interference filters has revealed 35 new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41 Hα emissionline stars, 30 of them new. A small cluster of partly embedded pre-main sequence stars is located around the known LkHα 185-189 group of stars, which includes the recently erupting FUor HBC 722.

Long-term photometric observations of pre-main sequence objects in the field of North America/Pelican Nebula

“…A.1). Our findings agrees with the classification of objects given by Armond et al (2011) as CTTS stars.…”

“…In Kohoutek & Wehmeyer (1997), brightness in the visual or photovisual color system (m pv = 17. m 0) and spectral type K6IVe is given. Ducourant et al (2005) Our measurements indicate the same range of V values as in Armond et al (2011), Cohen & Kuhi (1979, Kohoutek & Wehmeyer (1997), and Laugalys et al (2006), while mean magnitude in I band is for about 1 mag less. The R band displays least scatter of measurements, which are in accordance with the data of Armond et al (2011).…”

“…The V magnitude was determined to be V = 17. m 20 and the spectrum of the star estimated as M2. Armond et al (2011) report a lack of Hα emission from this star.…”

“…Adding to this, observations of PMS stars are usually made difficult by their faintness in quiescence and by the disturbance from sometimes heavy dust extinction, either surrounding the star or diffuse through the star forming region. Therefore, the rare outbursts of PMS stars always attract considerable interest, especially when they are long lasting, as in the case of new FUor objects (from the name of the prototype of this class, FU Ori), with one of the most recent and spectacular cases being that of HBC 722 = V2493 Cyg (Semkov et al 2010;Miller et al 2011;Munari et al 2010;Leoni et al 2010;Kóspál et al 2011;Armond et al 2011;Green et al 2011).…”

“…Since Herbig's (1958) discovery, it has been known to contain a number of PMS stars, among which are T Tauri and Hα emission stars, Herbig-Haro objects, and flare stars from the UV Ceti type (Armond et al 2011;Semkov et al 2012;Findeisen et al 2013). The largest number of young stars are found in the so-called Pelican Nebula (IC 5070), a few in the North America (NGC 7000) near "Florida", and in the "Gulf of Mexico" region between the two nebulas (Corbally et al 2009).…”