Coronal C+3 in the large magellanic cloud: Evidence for a hot halo

Bart Wakker; J. Chris Howk; You Hua Chu; Dominik Bomans; Sean D. Points

doi:10.1086/311334

Coronal C⁺³ in the large magellanic cloud: Evidence for a hot halo

Bart Wakker, J. Chris Howk, You Hua Chu, Dominik Bomans, Sean D. Points

Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

Based on the detection of C IV absorption in five Large Magellanic Cloud (LMC) stars observed with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope, we present the first unambiguous evidence that C⁺³ exists in the LMC away from regions where it could have been locally produced. We can exclude that this C⁺³ is associated with hot early-type stars or active regions. Significant differences between the Hα and C⁺³ velocities toward our probes indicate that H⁺ and C⁺³ are not cospatial. Large column density variations show that the distribution of C⁺³ is not uniform. The properties of the LMC C IV lines are similar but not identical to those found for the Milky Way: 45 km s^-1 versus 73 km s^-1 for the average FWHM, (8-12) × 10¹³ cm^-2 versus (9-16) × 10¹³ cm^-2 for the average column density. The Ha versus C IV velocity differences and the similarity of the properties of the LMC and Milky Way C IV absorption suggest that at least some of the C⁺³ in the LMC is in a hot corona and that it has been produced by processes similar to those in the Milky Way. Our results show the feasibility of detecting high-ionization absorption in faint LMC stars, but more observations will be necessary before we can understand the distribution and properties of 10⁵ K gas in the LMC.

Original language	English (US)
Pages (from-to)	L87-L91
Journal	Astrophysical Journal
Volume	499
Issue number	1 PART II
DOIs	https://doi.org/10.1086/311334
State	Published - 1998

Keywords

Galaxies: ISM
Galaxies: halos
ISM: structure
Magellanic Clouds
Ultraviolet: ISM

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Online availability

10.1086/311334

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@article{00c176ee8930475b9840c06fe8fbe6cd,

title = "Coronal C+3 in the large magellanic cloud: Evidence for a hot halo",

abstract = "Based on the detection of C IV absorption in five Large Magellanic Cloud (LMC) stars observed with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope, we present the first unambiguous evidence that C+3 exists in the LMC away from regions where it could have been locally produced. We can exclude that this C+3 is associated with hot early-type stars or active regions. Significant differences between the Hα and C+3 velocities toward our probes indicate that H+ and C+3 are not cospatial. Large column density variations show that the distribution of C+3 is not uniform. The properties of the LMC C IV lines are similar but not identical to those found for the Milky Way: 45 km s-1 versus 73 km s-1 for the average FWHM, (8-12) × 1013 cm-2 versus (9-16) × 1013 cm-2 for the average column density. The Ha versus C IV velocity differences and the similarity of the properties of the LMC and Milky Way C IV absorption suggest that at least some of the C+3 in the LMC is in a hot corona and that it has been produced by processes similar to those in the Milky Way. Our results show the feasibility of detecting high-ionization absorption in faint LMC stars, but more observations will be necessary before we can understand the distribution and properties of 105 K gas in the LMC.",

keywords = "Galaxies: ISM, Galaxies: halos, ISM: structure, Magellanic Clouds, Ultraviolet: ISM",

author = "Bart Wakker and Howk, {J. Chris} and Chu, {You Hua} and Dominik Bomans and Points, {Sean D.}",

note = "Funding Information: 2 Visiting astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation. 3 Feodor Lynen Fellow of the Alexander von Humboldt Foundation. Funding Information: 1 Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also based on observations with the IUE satellite, sponsored and operated by NASA, by the Science and Engineering Research Council, and by the European Space Agency. Funding Information: Support for this work was provided by NASA through grants GO-05894-01.94A and GO-05894.02-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Y.-H. Chu and B. Wakker acknowledge the support of NASA grant NAG5-3246. D. Bo-mans thanks the Alexander von Humboldt Foundation for their support. J. C. Howk is supported by a NASA Graduate Student Researcher Fellowship under grant S97-GSRP-013.",

year = "1998",

doi = "10.1086/311334",

language = "English (US)",

volume = "499",

pages = "L87--L91",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1 PART II",

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TY - JOUR

T1 - Coronal C+3 in the large magellanic cloud

T2 - Evidence for a hot halo

AU - Wakker, Bart

AU - Howk, J. Chris

AU - Chu, You Hua

AU - Bomans, Dominik

AU - Points, Sean D.

N1 - Funding Information: 2 Visiting astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation. 3 Feodor Lynen Fellow of the Alexander von Humboldt Foundation. Funding Information: 1 Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also based on observations with the IUE satellite, sponsored and operated by NASA, by the Science and Engineering Research Council, and by the European Space Agency. Funding Information: Support for this work was provided by NASA through grants GO-05894-01.94A and GO-05894.02-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Y.-H. Chu and B. Wakker acknowledge the support of NASA grant NAG5-3246. D. Bo-mans thanks the Alexander von Humboldt Foundation for their support. J. C. Howk is supported by a NASA Graduate Student Researcher Fellowship under grant S97-GSRP-013.

PY - 1998

Y1 - 1998

N2 - Based on the detection of C IV absorption in five Large Magellanic Cloud (LMC) stars observed with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope, we present the first unambiguous evidence that C+3 exists in the LMC away from regions where it could have been locally produced. We can exclude that this C+3 is associated with hot early-type stars or active regions. Significant differences between the Hα and C+3 velocities toward our probes indicate that H+ and C+3 are not cospatial. Large column density variations show that the distribution of C+3 is not uniform. The properties of the LMC C IV lines are similar but not identical to those found for the Milky Way: 45 km s-1 versus 73 km s-1 for the average FWHM, (8-12) × 1013 cm-2 versus (9-16) × 1013 cm-2 for the average column density. The Ha versus C IV velocity differences and the similarity of the properties of the LMC and Milky Way C IV absorption suggest that at least some of the C+3 in the LMC is in a hot corona and that it has been produced by processes similar to those in the Milky Way. Our results show the feasibility of detecting high-ionization absorption in faint LMC stars, but more observations will be necessary before we can understand the distribution and properties of 105 K gas in the LMC.

AB - Based on the detection of C IV absorption in five Large Magellanic Cloud (LMC) stars observed with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope, we present the first unambiguous evidence that C+3 exists in the LMC away from regions where it could have been locally produced. We can exclude that this C+3 is associated with hot early-type stars or active regions. Significant differences between the Hα and C+3 velocities toward our probes indicate that H+ and C+3 are not cospatial. Large column density variations show that the distribution of C+3 is not uniform. The properties of the LMC C IV lines are similar but not identical to those found for the Milky Way: 45 km s-1 versus 73 km s-1 for the average FWHM, (8-12) × 1013 cm-2 versus (9-16) × 1013 cm-2 for the average column density. The Ha versus C IV velocity differences and the similarity of the properties of the LMC and Milky Way C IV absorption suggest that at least some of the C+3 in the LMC is in a hot corona and that it has been produced by processes similar to those in the Milky Way. Our results show the feasibility of detecting high-ionization absorption in faint LMC stars, but more observations will be necessary before we can understand the distribution and properties of 105 K gas in the LMC.

KW - Galaxies: ISM

KW - Galaxies: halos

KW - ISM: structure

KW - Magellanic Clouds

KW - Ultraviolet: ISM

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