Crowded field 3D spectroscopy of LBV candidates in M 33

Fabrika, S.; Sholukhova, O.; Becker, T.; Afanasiev, V. L.; Roth, Martin; Sanchez, Sebastian Francisco Sanchez

doi:10.1051/0004-6361:20035824

Cited by 39 publications

(59 citation statements)

References 30 publications

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“…The described relation of Hei(4471) flux with the LBV Vband luminosity differs from that found in the systematic study of LBV V532 in the Local Group galaxy Messier 33 (Sholukhova et al 2011;Fabrika et al 2005). They found that during eleven years variations, F (Hei 4471) and F (Hei 5876) correlated with V532 optical luminosity variations for the total amplitude of ∆B =1.6 m .…”

Section: Ddo 68-v1 Spectral Variations In Comparisoncontrasting

confidence: 60%

The extremely metal-poor galaxy DDO 68: the luminous blue variable, Hα shells and the most luminous stars

Pustilnik¹,

Макарова²,

Perepelitsyna³

et al. 2016

Mon. Not. R. Astron. Soc.

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The paper presents new results of the ongoing study of the unusual Lynx-Cancer void galaxy DDO 68 with record-low-metallicity regions (12+log(O/H)∼7.14) of the current star formation (SF). They include: a) a new spectrum and photometry with the 6-m SAO RAS telescope (BTA) for the Luminous Blue Variable (LBV = DDO68-V1). Photometric data sets are complemented with those based on the Sloan Digital Sky Survey (SDSS) and the Hubble Space Telescope (HST) archive images; b) the analysis of the DDO 68 supergiant shell (SGS) and the prominent smaller Hα arcs/shells visible at the HST image coupled with kinematics maps in Hα obtained with the Fabry-Perot interferometer (FPI) at the BTA; c) the list of identified at the HST images of about 50 most luminous stars (−9.1 < M V < −6.0 mag) related to star-forming regions with the known extremely low O/H. This is intended to pave the path for the actual science with the next generation of giant telescopes. We confirm the earlier hints on significant variations of the LBV optical light deriving its amplitude of ∆V 3.7 mag for the first time. New data suggest that in 2008-2010 the LBV reached M V = -10.5 and probably underwent a giant eruption. We argue that the structure of star-forming complexes along the SGS ('Northern Ring') perimeter provides evidence for the sequential induced SF episodes caused by the shell gas instabilities and gravitational collapse. The variability of some DDO 68 luminous extremely metal-poor stars can be monitored with medium-size telescopes at sites with superb seeing.

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Section: Ddo 68-v1 Spectral Variations In Comparisoncontrasting

confidence: 60%

The extremely metal-poor galaxy DDO 68: the luminous blue variable, Hα shells and the most luminous stars

Pustilnik¹,

Макарова²,

Perepelitsyna³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…When the spatial resolution is good enough to resolve the more luminous H ii regions, it is still possible to use techniques of crowded field spectroscopy (Fabrika et al 2005;Kamann et al 2013). These techniques are extensions to IFS of the well-known PSF-photometric techniques (DAOPhot), and they rely on the basis that the considered regions are basically unresolved at the spatial resolution of the data.…”

Section: Line Ratios and Abundancesmentioning

confidence: 99%

The effects of spatial resolution on integral field spectrograph surveys at different redshifts − The CALIFA perspective

Mast

Rosales-Ortega

Sánchez

et al. 2014

A&A

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Context. Over the past decade, 3D optical spectroscopy has become the preferred tool for understanding the properties of galaxies and is now increasingly used to carry out galaxy surveys. Low redshift surveys include SAURON, DiskMass, ATLAS3D, PINGS, and VENGA. At redshifts above 0.7, surveys such as MASSIV, SINS, GLACE, and IMAGES have targeted the most luminous galaxies to study mainly their kinematic properties. The on-going CALIFA survey (z ∼ 0.02) is the first of a series of upcoming integral field spectroscopy (IFS) surveys with large samples representative of the entire population of galaxies. Others include SAMI and MaNGA at lower redshift and the upcoming KMOS surveys at higher redshift. Given the importance of spatial scales in IFS surveys, the study of the effects of spatial resolution on the recovered parameters becomes important. Aims. We explore the capability of the CALIFA survey and a hypothetical higher redshift survey to reproduce the properties of a sample of objects observed with better spatial resolution at lower redshift. Methods. Using a sample of PINGS galaxies, we simulated observations at different redshifts. We then studied the behaviour of different parameters as the spatial resolution degrades with increasing redshift. Results. We show that at the CALIFA resolution, we are able to measure and map common observables in a galaxy study: the number and distribution of H ii regions (Hα flux structure), the gas metallicity (using the O3N2 method), the gas ionization properties (through the [N ii]/Hα and [O iii]/Hβ line ratios), and the age of the underlying stellar population (using the D 4000 index). This supports the aim of the survey to characterise the observable properties of galaxies in the Local Universe. Our analysis of simulated IFS data cubes at higher redshifts highlights the importance of the projected spatial scale per spaxel as the most important figure of merit in the design of an integral field survey.

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“…Similar changes in the Balmer series over an identical time period are also seen in J013324.62+302328.4, with a dramatic decrease in the strength of Hβ between the two observations. A number of spectra of J013406.63+304147.8 are present in the literature, dating from from 1993-5 (Massey et al 2006), with subsequent spectra published by Shemmer et al (2000), Sholukhova et al (2011) andFabrika et al (2005). While significant multiyear gaps exist between these observations, comparison of these to our new spectra suggests that there has been a lack of conspicuous variability over this ∼17 yr period, with only minor changes in the line profile of He i 4471 Å and the anomalously strong Fe ii 4556 Å line at a single epoch 5 .…”

Section: Iron Starsmentioning

confidence: 99%

“…(a) Ma07, (b) Massey et al (1996), (c) Fabrika et al (2005), (d) Neugent & Massey (2011), (e) Viotti et al (2006), ( f ) Monteverde et al (1996). Stars for which contemporaneous historical observations of the ∼6000−7000 Å window are also available in the literature are indicated by an asterix.…”

Section: Introductionmentioning

confidence: 99%

On the nature of candidate luminous blue variables in M 33

Clark

Castro

García

et al. 2012

A&A

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Context. Luminous blue variables (LBVs) are a class of highly unstable stars that have been proposed to play a critical role in massive stellar evolution as well as being the progenitors of some of the most luminous supernovae known. However the physical processes underlying their characteristic instabilities are currently unknown. Aims. In order to provide observational constraints on this behaviour we have initiated a pilot study of the population of (candidate) LBVs in the Local Group galaxy M 33. Methods. To accomplish this we have obtained new spectra of 18 examples within M 33. These provide a baseline of ≥4 yr with respect to previous observations, which is well suited to identifying LBV outbursts. We also employed existing multi-epoch optical and mid-IR surveys of M 33 to further constrain the variability of the sample and search for the presence of dusty ejecta. Results. Combining the datasets reveals that spectroscopic and photometric variability appears common, although in the majority of cases further observations will be needed to distinguish between an origin for this behavour in short lived stochastic wind structure and low level photospheric pulsations or coherent long term LBV excursions. Of the known LBVs we report a hitherto unidentified excursion of M 33 Var C between 2001-5, while the transition of the WNLh star B517 to a cooler B supergiant phase between 1993−2010 implies an LBV classification. Proof-of-concept quantitative model atmosphere analysis is provided for Romano's star; the resultant stellar parameters being consistent with the finding that the LBV excursions of this star are accompanied by changes in bolometric luminosity. The combination of temperature and luminosity of two stars, the BHG [HS80] 110A and the cool hypergiant B324, appear to be in violation of the empirical Humphreys-Davidson limit. Mid-IR observations demonstrate that a number of candidates appear associated with hot circumstellar dust, although no objects as extreme as η Car are identified. The combined dataset suggests that the criteria employed to identify candidate LBVs results in a heterogeneous sample, also containing stars demonstrating the B[e] phenomenon. Of these, a subset of optically faint, low luminosity stars associated with hot dust are of particular interest since they appear similar to the likely progenitor of SN 2008S and the 2008 NGC 300 transient (albeit suffering less intrinsic extinction). Conclusions. The results of such a multiwavelength observational approach, employing multiplexing spectrographs and supplemented with quantitative model atmosphere analysis, appears to show considerable promise in both identifying and characterising the physical properties of LBVs as well as other short lived phases of massive stellar evolution.

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Crowded field 3D spectroscopy of LBV candidates in M 33

Cited by 39 publications

References 30 publications

The extremely metal-poor galaxy DDO 68: the luminous blue variable, Hα shells and the most luminous stars

The extremely metal-poor galaxy DDO 68: the luminous blue variable, Hα shells and the most luminous stars

The effects of spatial resolution on integral field spectrograph surveys at different redshifts − The CALIFA perspective

On the nature of candidate luminous blue variables in M 33

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