Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from the VVV survey. (arXiv:2401.14464v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Guo_Z/0/1/0/all/0/1">Zhen Guo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lucas_P/0/1/0/all/0/1">P. W. Lucas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kurtev_R/0/1/0/all/0/1">R. Kurtev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Borissova_J/0/1/0/all/0/1">J. Borissova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pena_C/0/1/0/all/0/1">C. Contreras Pe&#xf1;a</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yurchenko_S/0/1/0/all/0/1">S. N. Yurchenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_L/0/1/0/all/0/1">L. C. Smith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Minniti_D/0/1/0/all/0/1">D. Minniti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saito_R/0/1/0/all/0/1">R. K. Saito</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bayo_A/0/1/0/all/0/1">A. Bayo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Catelan_M/0/1/0/all/0/1">M. Catelan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alonso_Garcia_J/0/1/0/all/0/1">J. Alonso-Garc&#xed;a</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garatti_A/0/1/0/all/0/1">A. Caratti o Garatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morris_C/0/1/0/all/0/1">C. Morris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Froebrich_D/0/1/0/all/0/1">D. Froebrich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tennyson_J/0/1/0/all/0/1">J. Tennyson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mauco_K/0/1/0/all/0/1">K. Mauc&#xf3;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aguayo_A/0/1/0/all/0/1">A. Aguayo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miller_N/0/1/0/all/0/1">N. Miller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muthu_H/0/1/0/all/0/1">H. D. S. Muthu</a>

During the pre-main-sequence (pre-MS) evolution stage of a star, significant
amounts of stellar mass are accreted during episodic accretion events, such as
multi-decade FUor-type outbursts. Here, we present a near-infrared
spectroscopic follow-up study of 33 high-amplitude (most with $Delta K_s$ > 4
mag) variable sources discovered by the Vista Variables in the Via Lactea (VVV)
survey. Based on the spectral features, 25 sources are classified as eruptive
young stellar objects (YSOs), including 15 newly identified FUors, six with
long-lasting but EXor-like bursts of magnetospheric accretion and four
displaying outflow-dominated spectra. By examining the photometric behaviours
of eruptive YSOs, we found most FUor-type outbursts have higher amplitudes
($Delta K_s$ and $Delta W2$), faster eruptive timescales and bluer infrared
colours than the other outburst types. In addition, we identified seven
post-main sequence variables apparently associated with deep dipping events and
an eruptive star with deep AlO absorption bands resembling those seen in the
V838 Mon stellar merger.

During the pre-main-sequence (pre-MS) evolution stage of a star, significant
amounts of stellar mass are accreted during episodic accretion events, such as
multi-decade FUor-type outbursts. Here, we present a near-infrared
spectroscopic follow-up study of 33 high-amplitude (most with $Delta K_s$ > 4
mag) variable sources discovered by the Vista Variables in the Via Lactea (VVV)
survey. Based on the spectral features, 25 sources are classified as eruptive
young stellar objects (YSOs), including 15 newly identified FUors, six with
long-lasting but EXor-like bursts of magnetospheric accretion and four
displaying outflow-dominated spectra. By examining the photometric behaviours
of eruptive YSOs, we found most FUor-type outbursts have higher amplitudes
($Delta K_s$ and $Delta W2$), faster eruptive timescales and bluer infrared
colours than the other outburst types. In addition, we identified seven
post-main sequence variables apparently associated with deep dipping events and
an eruptive star with deep AlO absorption bands resembling those seen in the
V838 Mon stellar merger.

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