Pith. sign in

REVIEW 4 major objections 5 minor 42 references

Halpha emission-line stars in molecular clouds III. Canis Major

T0 review · 4 major / 5 minor · reviewed 2026-08-14 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read The Canis Major star-forming region is pinned at 1185 ± 25 parsecs by Gaia parallaxes of 98 newly catalogued hydrogen-alpha emission stars, settling a long-disputed distance.

desk verdict A solid Hα survey catalog and two new HH objects, but the headline Gaia distance of 1185±25 pc is softer than it looks: the parallax window is post-hoc and the DR2 zero-point is unaddressed. read the letter →

arxiv 1908.11446 v1 pith:5DRPARVQ submitted 2019-08-29 astro-ph.SR astro-ph.GA

B. Pettersson , B. Reipurth This is my paper · ORCID
classification astro-ph.SRastro-ph.GA
keywords Hαemission-linestarsCanisMajorOB1associationGaiaDR2parallaxesyoungstellarobjectsClassIIYSOsHerbig-Haroobjective-prismsurveystar-formingregions
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper establishes a distance for the Canis Major star-forming region: $1185 \pm 25$ pc, measured from the Gaia DR2 parallaxes of 98 young H$\alpha$-emitting stars and independently confirmed by 51 OB stars at a median of $1182$ pc. The value settles a long dispute in which earlier estimates ranged from 690 to 1150 pc. Along the way the survey expands the known population within its 14 square degrees from 45 previously catalogued H$\alpha$ emitters to 398 objects, of which 353 are new, and shows that the large majority of these are Class II pre-main-sequence stars with dusty discs. Getting the distance right matters because it converts every measured brightness in the region into a luminosity, mass, and age, and because the shell size of about 50 pc at this distance supports the picture of supernova-triggered sequential star formation.

What carries the argument

The central mechanism is the distance histogram built from Gaia DR2 parallaxes of objective-prism-selected H$\alpha$ emitters. The survey itself is a photographic objective-prism campaign on a Schmidt telescope: seven films with dispersion of 800 Å per millimetre at H$\alpha$, covering about 14 square degrees, from which 398 emission stars were catalogued at 2MASS positions. The distance result is carried by the 98 members of that sample with parallax errors below 20 per cent and nominal distances between 1050 and 1350 pc, the window drawn around the pronounced peak at 1185 pc; the same window applied to 51 OB stars from the Claría and Shevchenko membership lists provides the independent confirmation. Classification of the sources as mostly Class II young stellar objects rests on WISE colours, using the empirically calibrated Class I/II/III boundaries.

What would settle it

Two checks would settle the claim. First, recompute the median distance using only the roughly 221 stars with WISE colours in the Class II region, where foreground dMe contamination should be negligible, and see whether the median moves by more than 25 pc from 1185 pc. Second, re-derive the distance from Gaia eDR3 or DR3 parallaxes of the same 98 stars, whose individual errors would shrink and whose systematic offsets at 1.18 kpc would become apparent; a persisted shift beyond $\pm 25$ pc would show that the window selection was biasing the answer.

Watch

Extended reading notes

Core claim

The paper's central claim is that the CMa OB1 association and its surrounding clouds lie at $1185 \pm 25$ pc. From the 398 H$\alpha$ emitters found in the objective-prism survey, the authors take the 98 stars with Gaia DR2 parallax errors under 20 per cent and nominal distances in the 1050 to 1350 pc interval that brackets the histogram peak; this sample has a mean distance of 1184 pc, a median of 1185 pc, and a standard deviation of 70 pc. Applying the same selection to 51 OB stars from earlier membership compilations gives a median of 1182 pc, essentially identical. Because the association's shell spans about 50 pc across, the authors adopt a fundamental uncertainty of $\pm 25$ pc rather than the 7.1 pc standard error of the median, and state flatly that 'the best distance estimate is $1185 \pm 25$ pc'. This places the region at the far end of the earlier 690 to 1150 pc range and agrees with the extinction-based value of $1150 \pm 64$ pc.

Load-bearing premise

The distance claim rests on the assumption that the 98 H$\alpha$ stars inside the 1050 to 1350 pc window, which was drawn around the observed distance peak, are unbiased members of the CMa OB1 association rather than a mix that includes foreground dMe dwarfs and background Be stars whose median happens to fall in that same window.

Editorial extensions

If this is right

  • All derived properties of the young stars — luminosities, masses, ages, disc fractions — are anchored to a single distance of $1185 \pm 25$ pc instead of a disputed 690 to 1150 pc range.
  • At this distance the association's shell, about 50 pc across, is physically real, supporting the supernova-triggered star formation scenario; both runaway candidates, HD 54662 at 1170 pc and HD 57682 at 1241 pc, are consistent with membership.
  • Of the 300 H$\alpha$ emitters with usable WISE photometry, 221 fall in the Class II region, so the survey reveals a dominant population of disc-bearing young stellar objects whose H$\alpha$ strength tracks accretion activity.
  • The two new Herbig-Haro objects, HH 1174 and HH 1175, trace ongoing outflow activity inside the L1657 cloud, with HH 1175 only 3 arcsec from its likely embedded driving source.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The same survey series has already mapped H$\alpha$ emission populations in NGC 2264 and the Orion region; with Canis Major added, the three regions can be compared on a homogeneous basis, and the distance ratios between them then depend on Gaia parallax quality rather than on method-dependent photometry.
  • The contrast in near-infrared excess fractions, 44 per cent here versus 16 per cent around the Orion Nebula Cluster, suggests that the ambient ultraviolet field erodes discs faster; a testable extension would be to plot the disc fraction of the Canis Major sample against projected distance from the central OB stars and look for a gradient.
  • A cheap internal check of the distance assumption would be to test for a correlation between the measured distance of the 98 stars and their H$\alpha$ strength or WISE class; if Class I or strong-line objects sit systematically closer or farther than Class III objects, the window-based median is mixing distinct populations.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 5 minor

Summary. The paper presents a deep objective-prism Hα survey of approximately 14 square degrees toward the Canis Major star-forming region, detecting 398 Hα emitters, of which 353 are new. It provides coordinates from 2MASS, near-IR and WISE photometry, Gaia DR2 cross-matches, and finding charts for all new objects. Using Gaia DR2 parallaxes, the authors estimate the distance to the CMa OB1 association: after selecting 98 Hα emitters with parallax errors below 20% and nominal distances in the interval 1050–1350 pc, they find a median distance of 1185 pc; a similarly selected sample of 51 OB stars gives a median of 1182 pc. The paper concludes that the best distance estimate is 1185±25 pc, two runaway stars are confirmed as association members, and two new Herbig-Haro objects (HH 1174 and HH 1175) are identified with likely driving sources.

Significance. The catalog itself is a solid and useful contribution: it roughly triples the known Hα emitters in the region, provides homogeneous astrometry and photometry in a single table, and offers identification charts for all new sources. The WISE color classification and the detection of two new HH objects add value for future studies of young stellar objects in Canis Major. If the Gaia-based distance of ~1185 pc is correct, it resolves a long-standing discrepancy between photometric distance estimates (690–1150 pc) and places the association at the far end of the previously accepted range. The claim, however, depends on a distance estimate that ignores a known Gaia DR2 systematic and on a selection window chosen around the observed peak; these issues must be addressed before the central result can be considered robust.

major comments (4)
  1. [Section 3.4] The quoted '1185±25 pc' is derived from Gaia DR2 parallaxes without applying or discussing the known DR2 parallax zero-point offset. At the median parallax of about 0.84 mas, a −0.03 mas offset shifts individual distances by roughly 40–50 pc and moves the median from 1185 pc to approximately 1145 pc. This is a coherent systematic that affects the Hα and OB samples identically, so it is not cancelled by their mutual agreement, and it is not included in the 7.1 pc standard error or the ad hoc ±25 pc uncertainty. Please apply a zero-point correction (or fold the zero-point uncertainty into the reported error budget) and recompute the distance estimate.
  2. [Section 3.4] The selection of the 1050–1350 pc interval around the observed peak makes the reported median and standard error conditional on that window. The 'standard error of 7.1 pc' is the internal scatter of the selected sample divided by √98 and does not capture the uncertainty introduced by choosing the interval boundaries around the peak. Please quantify the sensitivity of the median to the chosen window (e.g., by varying the boundaries) or provide an a priori justification for the interval, and report the resulting range of median distances.
  3. [Section 3.4, Conclusion item 8] The OB-star sample is 'culled in a similar way to the Hα emission-line stars,' meaning it is selected using the same 1050–1350 pc distance window. The agreement between the Hα and OB median distances (1185 vs 1182 pc) is therefore partly by construction and cannot be described as a fully independent corroboration of the distance. Please soften this claim or test the OB stars against a differently defined selection (e.g., without imposing the same distance window, or using only OB stars with membership criteria independent of parallax).
  4. [Table 2 and Section 3.4] The paper refers to 'distances extracted from Gaia-DR2,' but Gaia DR2 provides parallaxes, not distances. If the quoted distances are computed as 1/parallax, the median of such inverse-parallax distances can be biased even at 20% parallax error, and the quoted distance uncertainties are not well defined. Please state explicitly the transformation used, and consider using a probabilistic distance estimate (e.g., Bailer-Jones et al. 2018) or justify quantitatively that the bias is negligible for this sample.
minor comments (5)
  1. [Abstract and Section 3.4] The phrase 'distances extracted from Gaia-DR2' is imprecise; Gaia DR2 provides parallaxes, and the transformation to distance should be described.
  2. [Section 3.4] The reasoning behind the 'fundamental uncertainty of ∼±25 pc' from the shell diameter of 50 pc is not fully explained; please clarify the assumed geometry and how the line-of-sight depth is estimated, since the angular diameter alone does not fix the radial depth.
  3. [References] Given the high-precision distance claim based on Gaia DR2, the paper should cite and discuss the known parallax zero-point studies (e.g., Lindegren et al. 2018; Arenou et al. 2018).
  4. [Figure 10] Please state the bin width used in the distance histograms and clarify whether the plotted distances are the nominal 1/parallax values or a probability-inferred quantity.
  5. [Section 3.2] The conclusion that Hα strength does not correlate with extinction would be strengthened by a quantitative measure; as presented it rests on a visual comparison with an extinction map of limited resolution, which should be noted as a caveat.

Circularity Check

0 steps flagged · score 0.0 of 10

No circularity: the Gaia-based distance is an external measurement, not derived from the claimed result.

full rationale

The central distance claim, 1185±25 pc for CMa OB1, is derived from Gaia DR2 parallaxes of 98 H-alpha emission-line stars, with a corroborating median of 1182 pc from 51 OB stars. These are measured catalog quantities, not outputs of a model fitted to the target distance. The H-alpha stars were selected by objective-prism H-alpha emission and spatial concentration toward the molecular clouds, not by distance; the 1050-1350 pc window was chosen after inspecting the distance histogram, which is a selection effect rather than circular reasoning. The median of the truncated sample is still an empirical statistic, and the OB sample, although filtered with the same parallax-error and distance-interval criteria, contributes independent parallax data. No equation in the paper reduces to an input, and no fitted parameter is renamed as a prediction. The self-citations to Papers I and II concern survey technique only and are not load-bearing for the distance result. The paper's own caveat that the 7.1 pc standard error is meaningful only if all stars lie at one distance, and its adoption of ±25 pc from the shell size, is an uncertainty statement, not a circular step. The absence of a Gaia DR2 zero-point correction is a legitimate systematic-error concern, but it does not make the derivation circular. Overall, the derivation is self-contained against external data and no circular step is exhibited.

Assumptions & free parameters 2 free parameters · 5 assumptions · 0 invented entities

The central distance claim rests on selection choices (distance window and parallax error threshold) and on the reliability of Gaia DR2 parallaxes and the adopted OB star membership lists. The survey catalog itself depends on subjective visual classification of prism spectra.

free parameters (2)
  • Distance selection window = 1050 to 1350 pc
    Chosen post hoc around the observed distance peak for H-alpha stars; this window directly determines the quoted median (1185 pc) and the standard error (7.1 pc).
  • Parallax error threshold = 20%
    Applied to both H-alpha and OB star samples to define the 'reliable' subset; changing the threshold changes the sample and the median.
assumptions (5)
  • domain assumption Gaia DR2 parallaxes are accurate for these stars, with negligible uncorrected zero-point offset.
    The distance determination (Section 3.4) uses Gaia DR2 parallaxes directly; a systematic offset (e.g., ~0.03 mas) would shift the distance by a few tens of parsecs.
  • domain assumption The objective-prism H-alpha identification is reliable and the strength classes (1-5) are consistent.
    The survey is based on visual inspection of Schmidt films (Section 2); no quantitative confirmation of each emitter is provided.
  • domain assumption The extinction map of Dobashi et al. (2005) is accurate enough for the correlation analysis in Fig. 6.
    Used to associate H-alpha stars with molecular clouds; map resolution and accuracy limit the conclusion.
  • domain assumption WISE Class I/II/III boundaries from Koenig et al. (2012) apply to these sources.
    The classification in Fig. 8 relies on empirically calibrated boundaries.
  • domain assumption The OB star samples of Claría (1974a) and Shevchenko et al. (1999) are complete and correctly identified.
    Used for the comparison sample of 51 OB stars in the distance determination.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Halpha emission-line stars in molecular clouds III. Canis Major." pith.science (2026). https://pith.science/paper/5DRPARVQ

@misc{pith2026190811446,
  author       = {Pith},
  title        = {Pith review of: Halpha emission-line stars in molecular clouds III. Canis Major},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/5DRPARVQ}},
  note         = {Machine review of arXiv:1908.11446}
}
read the original abstract

A deep objective-prism survey for H-alpha emission stars towards the Canis Major star-forming clouds was performed. A total of 398 Halpha emitters were detected, 353 of which are new detections. There is a strong concentration of these H-alpha emitters towards the molecular clouds surrounding the CMa~OB1 association, and it is likely that these stars are young stellar objects recently born in the clouds. An additional population of H-alpha emitters is scattered all across the region, and probably includes unrelated foreground dMe stars and background Be stars. About 90% of the H-alpha emitters are detected by WISE, of which 75% was detected with usable photometry. When plotted in a WISE colour-colour diagram it appears that the majority are Class II YSOs. Coordinates and finding charts are provided for all the new stars, and coordinates for all the detections. We searched the Gaia-DR2 catalogue and from 334 Halpha emission stars with useful parallaxes, we selected a subset of 98 stars that have parallax errors of less than 20% and nominal distances in the interval 1050 to 1350 pc that surrounds a strong peak at 1185 pc in the distance distribution. Similarly, Gaia distances were obtained for 51 OB-stars located towards Canis Major and selected with the same parallax errors as the H-alpha stars. We find a median distance for the OB stars of 1182 pc, in excellent correspondence with the distance from the H-alpha stars. Two known runaway stars are confirmed as members of the association. Finally, two new Herbig-Haro objects are identified.

Figures

Figures reproduced from arXiv: 1908.11446 by the authors.

Figure 1
Figure 1. Red image from DSS2 showing surveyed area bordered by a black line. The distribution of all detected emission-line stars is shown, each marked as a red cross to the west of the OB association. A number of Hα emission-line stars have been found in Canis Major. Wackerling (1970) dis￾covered some in his early-type, emission-line survey across the sky, and Stephenson & Sanduleak (1977) included Canis Ma￾jor in their gen… view at source ↗
Figure 2
Figure 2. shows the numbers of Hα emitters distributed across the five relative strengths of Hα emission. 60% of the stars are found in strength 2 and 3. Strength 1 may be incomplete, since [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Distribution of J magnitudes of all detected stars as extracted from the 2MASS catalogue. marginal detections have been removed to ensure, as much as possible, that the list contains only bona fide Hα emitters, even at the expense of completeness. Seven films were examined, and in some cases the Hα strength was found to vary, and in such cases the lower value is shown in [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figures from the paper (8 more)
Figure 4
Figure 4. Figure 4: Distribution of detected emission-line stars superposed on an Av extinction map from Dobashi et al. (2005). Stars with Hα strength 1-2 are represented by green triangles and the stronger emitters with Hα strength 3-5 by red crosses. Article number, page 4 of 13 [PITH_…
Figure 6
Figure 6. Figure 6: Relative distribution of Hα-emitters as function of the extinction AV along the line of sight. The stronger-line stars do not show a higher affinity of association with molecular clouds than the weaker emission￾line stars. detected with the extinction mapping technique…
Figure 5
Figure 5. Figure 5: Enlargement of the distribution of Hα emitters towards L1657. Stars with Hα strength 1-2 are represented by green triangles and the stronger emitters with Hα strength 3-5 by red crosses. The shell-like structure surrounding the main group of OB stars is clearly outline…
Figure 8
Figure 8. Figure 8: Distribution in a WISE two-colour diagram, of weaker-lined stars (green triangles) and stronger-lined stars (red crosses). The dashed lines separate Class I, II and III sources, see discussion in Koenig et al. (2012) have used mid-infrared Spitzer and far-infrared Hers…
Figure 7
Figure 7. Figure 7: Near-IR colour-colour diagram based on 2MASS data show￾ing all Hα emitters in the survey with 2MASS detections in all three bands (JHKs) (except upper limits). Main sequence and giant loci from Bessell & Brett (1988), corrected to the 2MASS photometric system (Carpente…
Figure 9
Figure 9. Figure 9: Plot of distribution of Hα emission stars towards the Canis Ma￾jor star-forming region. Only stars with positive parallaxes nearer than 10 kpc are shown, a total of 327 stars. The stars are divided into nearby stars, from 0 to 800 pc, which are likely dMe dwarfs (blue)…
Figure 10
Figure 10. Figure 10: Histogram showing distribution of Hα emitters (red) as function of distance with OB stars (blue) overlaid. The large peak corresponds to the Canis Major association, and the small peak at 2900 pc is the cluster NGC 2345. at ∼2900 pc from the ∼70 Myr old cluster NGC 23…
Figure 11
Figure 11. Figure 11: The two Herbig-Haro objects discovered in this survey, HH 1174 and HH 1175, are seen in these Hα images, each 150 arc￾sec wide, corresponding to ∼0.85 pc. The HH objects are marked with arrows, and surrounding Hα emission stars are indicated by red circles. The probab…

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

42 extracted references · 35 canonical work pages

  1. [1]

    Ambartsumian, V . A. 1947, Stellar Evolution and Astrophysics (Armenian Acad. of Sci., Yerevan), 12–16

    work page 1947

  2. [2]

    W., Schmitt, J

    Berghoefer, T. W., Schmitt, J. H. M. M., & Cassinelli, J. P. 1996, A&AS, 118, 481

    work page 1996

  3. [3]

    2007, A&A, 473, L21

    Bertout, C., Siess, L., & Cabrit, S. 2007, A&A, 473, L21

    work page 2007

  4. [4]

    Bessell, M. S. & Brett, J. M. 1988, PASP, 100, 1134

    1988

  5. [5]

    1994, A&AS, 103, 541

    Brand, J., Cesaroni, R., Caselli, P., et al. 1994, A&AS, 103, 541

    work page 1994

  6. [6]

    M., Hillenbrand, L

    Carpenter, J. M., Hillenbrand, L. A., & Skrutskie, M. F. 2001, AJ, 121, 3160 Claría, J. J. 1974a, A&A, 37, 229 Claría, J. J. 1974b, AJ, 79, 1022 Comerón, F., Torra, J., & Gomez, A. E. 1998, A&A, 330, 975

    work page 2001

  7. [7]

    M., Hartmann, D., & Thaddeus, P

    Dame, T. M., Hartmann, D., & Thaddeus, P. 2001, ApJ, 547, 792

    2001

  8. [8]

    2011, PASJ, 63, S1

    Dobashi, K. 2011, PASJ, 63, S1

    work page 2011

Show all 42 references
  1. [9]

    2005, PASJ, 57, S1

    Dobashi, K., Uehara, H., Kandori, R., et al. 2005, PASJ, 57, S1

    2005

  2. [10]

    2013, ApJ, 772, 45

    Elia, D., Molinari, S., Fukui, Y ., et al. 2013, ApJ, 772, 45

    2013

  3. [11]

    2015, MNRAS, 448, 119

    Fernandes, B., Gregorio-Hetem, J., Montmerle, T., & Rojas, G. 2015, MNRAS, 448, 119

    2015

  4. [12]

    2019, arXiv e-prints, arXiv:1906.00113

    Fernandes, B., Montmerle, T., Santos-Silva, T., & Gregorio-Hetem, J. 2019, arXiv e-prints, arXiv:1906.00113

    2019 arXiv

  5. [13]

    J., Padgett, D

    Fischer, W. J., Padgett, D. L., Stapelfeldt, K. L., & Sewiło, M. 2016, ApJ, 827, 96 Gaia Collaboration, Clementini, G., Eyer, L., et al. 2017, A&A, 605, A79 Gaia Collaboration, Prusti, T., de Bruijne, J. H. J., et al. 2016, A&A, 595, A1

    2016

  6. [14]

    2008, in Handbook of Star Forming Regions, V olume II, ed

    Gregorio-Hetem, J. 2008, in Handbook of Star Forming Regions, V olume II, ed. B. Reipurth (ASP), 1

    2008

  7. [15]

    V ., et al

    Gregorio-Hetem, J., Montmerle, T., Rodrigues, C. V ., et al. 2009, A&A, 506, 711

    2009

  8. [16]

    J., Hewett, R., et al

    Hartmann, L., Kenyon, S. J., Hewett, R., et al. 1989, ApJ, 338, 1001

    1989

  9. [17]

    Herbig, G. H. 1954, ApJ, 119, 483

    1954

  10. [18]

    Herbig, G. H. 1960, ApJS, 4, 337

    1960

  11. [19]

    Herbig, G. H. 1991, in Low Mass Star Formation in Southern Molecular Clouds , ed. B. Reipurth, V ol. 11 (ESO Scientific Report), 59

    1991

  12. [20]

    Herbig, G. H. 1998, ApJ, 497, 736

    1998

  13. [21]

    Herbig, G. H. & Dahm, S. E. 2006, AJ, 131, 1530

    2006

  14. [22]

    & Assousa, G

    Herbst, W. & Assousa, G. E. 1977, ApJ, 217, 473

    1977

  15. [23]

    Kaltcheva, N. T. & Hilditch, R. W. 2000, MNRAS, 312, 753

    2000

  16. [24]

    P., Leisawitz, D

    Koenig, X. P., Leisawitz, D. T., Benford, D. J., et al. 2012, ApJ, 744, 130

    2012

  17. [25]

    Lombardi, M., Alves, J., & Lada, C. J. 2011, A&A, 535, A16

    2011

  18. [26]

    K., Ojha, D

    Mallick, K. K., Ojha, D. K., Samal, M. R., et al. 2012, ApJ, 759, 48

    2012

  19. [27]

    2018, A&A, 615, A19

    Mossoux, E., Mahy, L., & Rauw, G. 2018, A&A, 615, A19

    2018

  20. [28]

    2002, AJ, 123, 2597

    Ogura, K., Sugitani, K., & Pickles, A. 2002, AJ, 123, 2597

    2002

  21. [29]

    2014, A&A, 570, A30, (Paper II)

    Pettersson, B., Armond, T., & Reipurth, B. 2014, A&A, 570, A30, (Paper II)

    2014

  22. [30]

    M., Johnson, C

    Rebull, L. M., Johnson, C. H., Gibbs, J. C., et al. 2013, AJ, 145, 15

    2013

  23. [31]

    Reipurth, B., Pettersson, B., Armond, T., Bally, J., & Vaz, L. P. R. 2004, AJ, 127, 1117, (Paper I)

    2004

  24. [32]

    Rieke, G. H. & Lebofsky, M. J. 1985, ApJ, 288, 618

    1985

  25. [33]

    Schwartz, R. D. 1977, ApJS, 35, 161 Sewiło, M., Whitney, B. A., Yung, B. H. K., et al. 2019, ApJS, 240, 26

    1977

  26. [34]

    S., Ezhkova, O

    Shevchenko, V . S., Ezhkova, O. V ., Ibrahimov, M. A., van den Ancker, M. E., & Tjin A Djie, H. R. E. 1999, MNRAS, 310, 210

    1999

  27. [35]

    I., Dzura, A

    Slysh, V . I., Dzura, A. M., Val’tts, I. E., & Gerard, E. 1994, A&AS, 106, 87

    1994

  28. [36]

    Soares, J. B. & Bica, E. 2002, A&A, 388, 172

    2002

  29. [37]

    Soares, J. B. & Bica, E. 2003, A&A, 404, 217

    2003

  30. [38]

    Stephenson, C. B. & Sanduleak, N. 1977, ApJS, 33, 459

    1977

  31. [39]

    1995, ApJ, 455, L39 van den Bergh, S

    Sugitani, K., Tamura, M., & Ogura, K. 1995, ApJ, 455, L39 van den Bergh, S. 1966, AJ, 71, 990

    1995

  32. [40]

    Wackerling, L. R. 1970, MNRAS, 149, 405

    1970

  33. [41]

    F., Ran, L., Yu, W

    Wang, K., Wu, Y . F., Ran, L., Yu, W. T., & Miller, M. 2009, A&A, 507, 369

    2009

  34. [42]

    D., Kogure, T., Nakano, M., & Yoshida, S

    Wiramihardja, S. D., Kogure, T., Nakano, M., & Yoshida, S. 1986, PASJ, 38, 395 Article number, page 9 of 13 A&A proofs: manuscript no. aa31578-17 Appendix A: Finding Charts In this appendix we provide finding charts for all of the new Hα emission-line stars presented in this pa...

    1986

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.