Browsing University of Hertfordshire by Author "Morris, C."

Now showing items 1-8 of 8

    • Analysis of physical processes in eruptive YSOs with near infrared spectra and multi-wavelength light curves 

      Guo, Zhen; Lucas, P. W.; Contreras Pena, Carlos; Smith, L. C.; Morris, C.; Kurtev, R. G.; Borissova, J.; Alonso-García, J.; Minniti, D.; Chené, A. -N.; Kumar, M. S. N.; Garatti, A. Caratti o; Froebrich, D. (2021-03-26)
      The decade-long Vista Variables in the Via Lactea (VVV) survey has detected numerous highly variable young stellar objects (YSOs). We present a study of 61 highly variable VVV YSOs (Delta Ks = 1-5 mag), combining near ...

    • Discovery of a mid-infrared protostellar outburst of exceptional amplitude 

      Lucas, P. W.; Elias, Jay; Points, Sean; Guo, Z.; Stecklum, B.; Vorobyov, E.; Morris, C.; Borissova, J.; Kurtev, R.; Pena, C. Contreras; Medina, N.; Minniti, D.; Ivanov, V. D.; Saito, R. K. (2020-09-23)
      We report the discovery of a mid-infrared outburst in a Young Stellar Object (YSO) with an amplitude close to 8 mag at lambda ~ 4.6 microns. WISEA J142238.82-611553.7 is one of 23 highly variable WISE sources discovered ...

    • Large amplitude periodic outbursts and long period variables in the VVV VIRAC2-$β$ database 

      Guo, Zhen; Lucas, P. W.; Smith, L. C.; Clarke, C.; Peña, C. Contreras; Bayo, A.; Briceño, C.; Elias, J.; Kurtev, R. G.; Borissova, J.; Alonso-García, J.; Minniti, D.; Catelan, M.; Nikzat, F.; Morris, C.; Miller, N. (2022-03-21)
      The VISTA Variables in the Via Lactea (VVV) survey obtained near-infrared photometry toward the Galactic bulge and the southern disc plane for a decade (2010 - 2019). We designed a modified Lomb-Scargle method to search ...

    • The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others 

      Lucas, P. W.; Smith, L. C.; Guo, Z.; Peña, C. Contreras; Minniti, D.; Miller, N.; Alonso-García, Javier; Catelan, M.; Borissova, J.; Saito, R. K.; Kurtev, R.; Navarro, M. G.; Morris, C.; Muthu, H.; Froebrich, D.; Ivanov, V. D.; Bayo, A.; Garatti, A. Caratti o; Sanders, J. L. (2024-02-01)
      We have performed a comprehensive search of a VISTA Variables in the Via Lactea (VVV) data base of 9.5 yr light curves for variable sources with ΔKs ≥ 4 mag, aiming to provide a large sample of high amplitude eruptive young ...

    • Multiwavelength detection of an ongoing FUOr-type outburst on a low-mass YSO 

      Guo, Zhen; Lucas, P. W.; Kurtev, R. G.; Borissova, J.; Elbakyan, V.; Morris, C.; Bayo, A.; Smith, L.; Garatti, A. Caratti o; Peña, C. Contreras; Minniti, D.; Jose, J.; Ashraf, M.; Alonso-García, J; Miller, N.; Muthu, H. D. S. (2024-03-01)
      During the pre-main-sequence evolution, Young Stellar Objects (YSOs) assemble most of their mass during the episodic accretion process. The rarely seen FUOr-type events are valuable laboratories to investigate the outbursting ...

    • Photometric variability of massive young stellar objects 

      Teixeira, G. D. C.; Kumar, M. S. N.; Smith, L.; Lucas, P. W.; Morris, C.; Borissova, J.; Monteiro, M. J. P. F. G.; Garatti, A. Caratti o; Peña, C. Contreras; Froebrich, Dirk; Gameiro, J. F. (2018-11-05)
      The Vista Variables in the Via Lactea (VVV) survey has allowed for an unprecedented number of multi-epoch observations of the southern Galactic plane. In a recent paper, 13 massive young stellar objects (MYSOs) have already ...

    • Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from the VVV survey 

      Guo, Zhen; Lucas, P. W.; Kurtev, R.; Borissova, J.; Peña, C. Contreras; Yurchenko, S. N.; Smith, L. C.; Minniti, D.; Saito, R. K.; Bayo, A.; Catelan, M.; Alonso-García, Javier; Garatti, A. Caratti o; Morris, C.; Froebrich, D.; Tennyson, J.; Maucó, K.; Aguayo, A.; Miller, N.; Muthu, H. D. S. (2024-02-01)
      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 multidecade FUor-type outbursts. Here, we present a near-infrared ...

    • UGPS J194310+183851 : an Unusual Optical and X-ray Faint Cataclysmic Variable? 

      Morris, C.; Maccarone, T. J.; Lucas, P. W.; Strader, J.; Britt, C. T.; Miller, N.; Swihart, S. J.; Cooper, W. J.; Drew, J. E.; Guo, Z. (2022-08-01)
      The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared ...