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Title: THE ERUPTION OF THE CANDIDATE YOUNG STAR ASASSN-15QI

Abstract

Outbursts on young stars are usually interpreted as accretion bursts caused by instabilities in the disk or the star–disk connection. However, some protostellar outbursts may not fit into this framework. In this paper, we analyze optical and near-infrared spectra and photometry to characterize the 2015 outburst of the probable young star ASASSN-15qi. The ∼3.5 mag brightening in the V band was sudden, with an unresolved rise time of less than one day. The outburst decayed exponentially by 1 mag for 6 days and then gradually back to the pre-outburst level after 200 days. The outburst is dominated by emission from ∼10,000 K gas. An explosive release of energy accelerated matter from the star in all directions, seen in a spectacular cool, spherical wind with a maximum velocity of 1000 km s{sup −1}. The wind and hot gas both disappeared as the outburst faded and the source returned to its quiescent F-star spectrum. Nebulosity near the star brightened with a delay of 10–20 days. Fluorescent excitation of H{sub 2} is detected in emission from vibrational levels as high as v = 11, also with a possible time delay in flux increase. The mid-infrared spectral energy distribution does not indicate the presencemore » of warm dust emission, though the optical photospheric absorption and CO overtone emission could be related to a gaseous disk. Archival photometry reveals a prior outburst in 1976. Although we speculate about possible causes for this outburst, none of the explanations are compelling.« less

Authors:
; ; ; ;  [1];  [2];  [3]; ; ;  [4];  [5];  [6]; ;  [7];  [8];  [9];  [10];  [11];  [12];  [13] more »; « less
  1. Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, 100871 Beijing (China)
  2. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  3. Caltech, MC 105-24, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)
  4. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  5. Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago (Chile)
  6. Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States)
  7. Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada)
  8. Department of Astrophysical Sciences, 4 Ivy Lane, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)
  9. Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)
  10. Astrophysics Research Institute, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom)
  11. Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States)
  12. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
  13. Bisei Astronomical Observatory, 1723-70 Okura, Bisei, Ibara, Okayama 714-1411 (Japan)
Publication Date:
OSTI Identifier:
22667241
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 831; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; CARBON MONOXIDE; COSMIC DUST; DECAY; ENERGY SPECTRA; ERUPTION; EXCITATION; EXPLOSIVES; FLUORESCENCE; HYDROGEN; INFRARED SPECTRA; INSTABILITY; PHOTOMETRY; PULSE RISE TIME; STARS; STELLAR WINDS; TIME DELAY; VELOCITY

Citation Formats

Herczeg, Gregory J., Dong, Subo, Chen, Ping, Jose, Jessy, Gully-Santiago, Michael, Shappee, Benjamin J., Hillenbrand, Lynne A., Kochanek, Christopher S., Stanek, K. Z., Holoien, Thomas W.-S., Prieto, Jose L., Kaplan, Kyle, Mairs, Steve, Johnstone, Doug, Zhu, Zhaohuan, Smith, Martin C., Bersier, David, Mulders, Gijs D., Filippenko, Alexei V., Ayani, Kazuya, and others, and. THE ERUPTION OF THE CANDIDATE YOUNG STAR ASASSN-15QI. United States: N. p., 2016. Web. doi:10.3847/0004-637X/831/2/133.
Herczeg, Gregory J., Dong, Subo, Chen, Ping, Jose, Jessy, Gully-Santiago, Michael, Shappee, Benjamin J., Hillenbrand, Lynne A., Kochanek, Christopher S., Stanek, K. Z., Holoien, Thomas W.-S., Prieto, Jose L., Kaplan, Kyle, Mairs, Steve, Johnstone, Doug, Zhu, Zhaohuan, Smith, Martin C., Bersier, David, Mulders, Gijs D., Filippenko, Alexei V., Ayani, Kazuya, & others, and. THE ERUPTION OF THE CANDIDATE YOUNG STAR ASASSN-15QI. United States. doi:10.3847/0004-637X/831/2/133.
Herczeg, Gregory J., Dong, Subo, Chen, Ping, Jose, Jessy, Gully-Santiago, Michael, Shappee, Benjamin J., Hillenbrand, Lynne A., Kochanek, Christopher S., Stanek, K. Z., Holoien, Thomas W.-S., Prieto, Jose L., Kaplan, Kyle, Mairs, Steve, Johnstone, Doug, Zhu, Zhaohuan, Smith, Martin C., Bersier, David, Mulders, Gijs D., Filippenko, Alexei V., Ayani, Kazuya, and others, and. Thu . "THE ERUPTION OF THE CANDIDATE YOUNG STAR ASASSN-15QI". United States. doi:10.3847/0004-637X/831/2/133.
@article{osti_22667241,
title = {THE ERUPTION OF THE CANDIDATE YOUNG STAR ASASSN-15QI},
author = {Herczeg, Gregory J. and Dong, Subo and Chen, Ping and Jose, Jessy and Gully-Santiago, Michael and Shappee, Benjamin J. and Hillenbrand, Lynne A. and Kochanek, Christopher S. and Stanek, K. Z. and Holoien, Thomas W.-S. and Prieto, Jose L. and Kaplan, Kyle and Mairs, Steve and Johnstone, Doug and Zhu, Zhaohuan and Smith, Martin C. and Bersier, David and Mulders, Gijs D. and Filippenko, Alexei V. and Ayani, Kazuya and others, and},
abstractNote = {Outbursts on young stars are usually interpreted as accretion bursts caused by instabilities in the disk or the star–disk connection. However, some protostellar outbursts may not fit into this framework. In this paper, we analyze optical and near-infrared spectra and photometry to characterize the 2015 outburst of the probable young star ASASSN-15qi. The ∼3.5 mag brightening in the V band was sudden, with an unresolved rise time of less than one day. The outburst decayed exponentially by 1 mag for 6 days and then gradually back to the pre-outburst level after 200 days. The outburst is dominated by emission from ∼10,000 K gas. An explosive release of energy accelerated matter from the star in all directions, seen in a spectacular cool, spherical wind with a maximum velocity of 1000 km s{sup −1}. The wind and hot gas both disappeared as the outburst faded and the source returned to its quiescent F-star spectrum. Nebulosity near the star brightened with a delay of 10–20 days. Fluorescent excitation of H{sub 2} is detected in emission from vibrational levels as high as v = 11, also with a possible time delay in flux increase. The mid-infrared spectral energy distribution does not indicate the presence of warm dust emission, though the optical photospheric absorption and CO overtone emission could be related to a gaseous disk. Archival photometry reveals a prior outburst in 1976. Although we speculate about possible causes for this outburst, none of the explanations are compelling.},
doi = {10.3847/0004-637X/831/2/133},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 831,
place = {United States},
year = {2016},
month = {11}
}

Works referencing / citing this record:

The 2014–2017 outburst of the young star ASASSN-13db: A time-resolved picture of a very-low-mass star between EXors and FUors⋆
journal, November 2017