Query : 2010A&A...523L...3S

2010A&A...523L...3S - Astronomy and Astrophysics, volume 523, L3-3 (2010/11-2)

The large amplitude outburst of the young star HBC 722 in NGC 7000/IC 5070, a new FU Orionis candidate.


Abstract (from CDS):

The investigations of the photometric and spectral variability of PMS stars are essential to a better understanding of the early phases of stellar evolution. We are carrying out a photometric monitoring program of some fields of active star formation. One of our targets is the dark cloud region between the bright nebulae NGC 7000 and IC 5070. We report the discovery of a large amplitude outburst from the young star HBC 722 (LkHα 188 G4) located in the region of NGC 7000/IC 5070. On the basis of photometric and spectroscopic observations, we argue that this outburst is of the FU Orionis type. We gathered photometric and spectroscopic observations of the object both in the pre-outburst state and during a phase of increase in its brightness. The photometric BVRI data (Johnson-Cousins system) that we present were collected from April 2009 to September 2010. To facilitate transformation from instrumental measurements to the standard system, fifteen comparison stars in the field of HBC 722 were calibrated in the BVRI bands. Optical spectra of HBC 722 were obtained with the 1.3-m telescope of Skinakas Observatory (Crete, Greece) and the 0.6-m telescope of Schiaparelli Observatory in Varese (Italy). The pre-outburst photometric and spectroscopic observations of HBC 722 show both low amplitude photometric variations and an emission-line spectrum typical of T Tau stars. The observed outburst started before May 2010 and reached its maximum brightness in September 2010, with a recorded ΔV∼4.7mag amplitude. Simultaneously with the increase in brightness the color indices changed significantly and the star became appreciably bluer. The light curve of HBC 722 during the period of rise in brightness is similar to the light curves of the classical FUors - FU Ori and V1057 Cyg. The spectral observations during the time of increase in brightness showed significant changes in both the profiles and intensity of the spectral lines. Only Hα remained in emission, while the Hβ, Na I 5890/5896, Mg I triplet 5174, and Ba II 5854/6497 lines were in strong absorption.

Abstract Copyright:

Journal keyword(s): stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be - stars: individual: HBC 722

CDS comments: Table 1 calibration stars not in Simbad.

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* FU Ori Or* 05 45 22.3647842544 +09 04 12.291320064   10.72 9.60     F0Iab 787 1
2 V* V1647 Ori Or* 05 46 13.1370578472 -00 06 04.885093296     18.1     M3.9 272 1
3 HD 325367 Or* 16 03 05.4915085848 -40 18 25.426727676   11.40 8.50     M0 334 0
4 IC 5070 HII 20 51.0 +44 22           ~ 204 1
5 V* V2493 Cyg Or* 20 58 17.0280367392 +43 53 43.341681156   19.678 18.023 17.67 15.233 M4.6 113 0
6 NGC 7000 Cl* 20 58 47 +44 19.8           ~ 395 0
7 EM* LkHA 190 Or* 20 58 53.7335347296 +44 15 28.388727720   14.26 12.33 12.13   F7/G3I/IIe 504 0

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